]> git.madduck.net Git - etc/vim.git/blobdiff - tests/test_black.py

madduck's git repository

Every one of the projects in this repository is available at the canonical URL git://git.madduck.net/madduck/pub/<projectpath> — see each project's metadata for the exact URL.

All patches and comments are welcome. Please squash your changes to logical commits before using git-format-patch and git-send-email to patches@git.madduck.net. If you'd read over the Git project's submission guidelines and adhered to them, I'd be especially grateful.

SSH access, as well as push access can be individually arranged.

If you use my repositories frequently, consider adding the following snippet to ~/.gitconfig and using the third clone URL listed for each project:

[url "git://git.madduck.net/madduck/"]
  insteadOf = madduck:

Fix typo in `target-version` param wrongly used in plural (#3817)
[etc/vim.git] / tests / test_black.py
index 42ac119324c0c41abfc3545da83a7ff933832dfc..3b3ab721c5f21d1671057e07fa7c0a1f43de18ac 100644 (file)
@@ -1,72 +1,80 @@
 #!/usr/bin/env python3
-import multiprocessing
+
 import asyncio
+import inspect
+import io
 import logging
+import multiprocessing
+import os
+import re
+import sys
+import types
+import unittest
 from concurrent.futures import ThreadPoolExecutor
-from contextlib import contextmanager
+from contextlib import contextmanager, redirect_stderr
 from dataclasses import replace
-import inspect
-import io
 from io import BytesIO
-import os
 from pathlib import Path
 from platform import system
-import regex as re
-import sys
 from tempfile import TemporaryDirectory
-import types
 from typing import (
     Any,
     Callable,
     Dict,
-    List,
     Iterator,
+    List,
+    Optional,
+    Sequence,
+    Type,
     TypeVar,
+    Union,
 )
-import pytest
-import unittest
-from unittest.mock import patch, MagicMock
+from unittest.mock import MagicMock, patch
 
 import click
+import pytest
 from click import unstyle
 from click.testing import CliRunner
+from pathspec import PathSpec
 
 import black
+import black.files
 from black import Feature, TargetVersion
-from black.cache import get_cache_file
+from black import re_compile_maybe_verbose as compile_pattern
+from black.cache import get_cache_dir, get_cache_file
 from black.debug import DebugVisitor
-from black.output import diff, color_diff
+from black.output import color_diff, diff
 from black.report import Report
-import black.files
-
-from pathspec import PathSpec
 
 # Import other test classes
 from tests.util import (
-    THIS_DIR,
-    read_data,
+    DATA_DIR,
+    DEFAULT_MODE,
     DETERMINISTIC_HEADER,
+    PROJECT_ROOT,
+    PY36_VERSIONS,
+    THIS_DIR,
     BlackBaseTestCase,
-    DEFAULT_MODE,
-    fs,
-    ff,
+    assert_format,
+    change_directory,
     dump_to_stderr,
+    ff,
+    fs,
+    get_case_path,
+    read_data,
+    read_data_from_file,
 )
 
-
 THIS_FILE = Path(__file__)
-PY36_VERSIONS = {
-    TargetVersion.PY36,
-    TargetVersion.PY37,
-    TargetVersion.PY38,
-    TargetVersion.PY39,
-}
+EMPTY_CONFIG = THIS_DIR / "data" / "empty_pyproject.toml"
 PY36_ARGS = [f"--target-version={version.name.lower()}" for version in PY36_VERSIONS]
+DEFAULT_EXCLUDE = black.re_compile_maybe_verbose(black.const.DEFAULT_EXCLUDES)
+DEFAULT_INCLUDE = black.re_compile_maybe_verbose(black.const.DEFAULT_INCLUDES)
 T = TypeVar("T")
 R = TypeVar("R")
 
 # Match the time output in a diff, but nothing else
-DIFF_TIME = re.compile(r"\t[\d-:+\. ]+")
+DIFF_TIME = re.compile(r"\t[\d\-:+\. ]+")
 
 
 @contextmanager
@@ -96,6 +104,9 @@ class FakeContext(click.Context):
 
     def __init__(self) -> None:
         self.default_map: Dict[str, Any] = {}
+        self.params: Dict[str, Any] = {}
+        # Dummy root, since most of the tests don't care about it
+        self.obj: Dict[str, Any] = {"root": PROJECT_ROOT}
 
 
 class FakeParameter(click.Parameter):
@@ -112,52 +123,81 @@ class BlackRunner(CliRunner):
         super().__init__(mix_stderr=False)
 
 
-class BlackTestCase(BlackBaseTestCase):
-    def invokeBlack(
-        self, args: List[str], exit_code: int = 0, ignore_config: bool = True
-    ) -> None:
-        runner = BlackRunner()
-        if ignore_config:
-            args = ["--verbose", "--config", str(THIS_DIR / "empty.toml"), *args]
-        result = runner.invoke(black.main, args)
-        assert result.stdout_bytes is not None
-        assert result.stderr_bytes is not None
-        self.assertEqual(
-            result.exit_code,
-            exit_code,
-            msg=(
-                f"Failed with args: {args}\n"
-                f"stdout: {result.stdout_bytes.decode()!r}\n"
-                f"stderr: {result.stderr_bytes.decode()!r}\n"
-                f"exception: {result.exception}"
-            ),
-        )
+def invokeBlack(
+    args: List[str], exit_code: int = 0, ignore_config: bool = True
+) -> None:
+    runner = BlackRunner()
+    if ignore_config:
+        args = ["--verbose", "--config", str(THIS_DIR / "empty.toml"), *args]
+    result = runner.invoke(black.main, args, catch_exceptions=False)
+    assert result.stdout_bytes is not None
+    assert result.stderr_bytes is not None
+    msg = (
+        f"Failed with args: {args}\n"
+        f"stdout: {result.stdout_bytes.decode()!r}\n"
+        f"stderr: {result.stderr_bytes.decode()!r}\n"
+        f"exception: {result.exception}"
+    )
+    assert result.exit_code == exit_code, msg
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_empty(self) -> None:
-        source = expected = ""
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, DEFAULT_MODE)
+
+class BlackTestCase(BlackBaseTestCase):
+    invokeBlack = staticmethod(invokeBlack)
 
     def test_empty_ff(self) -> None:
         expected = ""
         tmp_file = Path(black.dump_to_file())
         try:
             self.assertFalse(ff(tmp_file, write_back=black.WriteBack.YES))
-            with open(tmp_file, encoding="utf8") as f:
-                actual = f.read()
+            actual = tmp_file.read_text(encoding="utf-8")
         finally:
             os.unlink(tmp_file)
         self.assertFormatEqual(expected, actual)
 
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_one_empty_line(self) -> None:
+        mode = black.Mode(preview=True)
+        for nl in ["\n", "\r\n"]:
+            source = expected = nl
+            assert_format(source, expected, mode=mode)
+
+    def test_one_empty_line_ff(self) -> None:
+        mode = black.Mode(preview=True)
+        for nl in ["\n", "\r\n"]:
+            expected = nl
+            tmp_file = Path(black.dump_to_file(nl))
+            if system() == "Windows":
+                # Writing files in text mode automatically uses the system newline,
+                # but in this case we don't want this for testing reasons. See:
+                # https://github.com/psf/black/pull/3348
+                with open(tmp_file, "wb") as f:
+                    f.write(nl.encode("utf-8"))
+            try:
+                self.assertFalse(
+                    ff(tmp_file, mode=mode, write_back=black.WriteBack.YES)
+                )
+                with open(tmp_file, "rb") as f:
+                    actual = f.read().decode("utf-8")
+            finally:
+                os.unlink(tmp_file)
+            self.assertFormatEqual(expected, actual)
+
+    def test_experimental_string_processing_warns(self) -> None:
+        self.assertWarns(
+            black.mode.Deprecated, black.Mode, experimental_string_processing=True
+        )
+
     def test_piping(self) -> None:
-        source, expected = read_data("src/black/__init__", data=False)
+        source, expected = read_data_from_file(PROJECT_ROOT / "src/black/__init__.py")
         result = BlackRunner().invoke(
             black.main,
-            ["-", "--fast", f"--line-length={black.DEFAULT_LINE_LENGTH}"],
-            input=BytesIO(source.encode("utf8")),
+            [
+                "-",
+                "--fast",
+                f"--line-length={black.DEFAULT_LINE_LENGTH}",
+                f"--config={EMPTY_CONFIG}",
+            ],
+            input=BytesIO(source.encode("utf-8")),
         )
         self.assertEqual(result.exit_code, 0)
         self.assertFormatEqual(expected, result.output)
@@ -167,21 +207,20 @@ class BlackTestCase(BlackBaseTestCase):
 
     def test_piping_diff(self) -> None:
         diff_header = re.compile(
-            r"(STDIN|STDOUT)\t\d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d\.\d\d\d\d\d\d "
-            r"\+\d\d\d\d"
+            r"(STDIN|STDOUT)\t\d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d\.\d\d\d\d\d\d"
+            r"\+\d\d:\d\d"
         )
-        source, _ = read_data("expression.py")
-        expected, _ = read_data("expression.diff")
-        config = THIS_DIR / "data" / "empty_pyproject.toml"
+        source, _ = read_data("simple_cases", "expression.py")
+        expected, _ = read_data("simple_cases", "expression.diff")
         args = [
             "-",
             "--fast",
             f"--line-length={black.DEFAULT_LINE_LENGTH}",
             "--diff",
-            f"--config={config}",
+            f"--config={EMPTY_CONFIG}",
         ]
         result = BlackRunner().invoke(
-            black.main, args, input=BytesIO(source.encode("utf8"))
+            black.main, args, input=BytesIO(source.encode("utf-8"))
         )
         self.assertEqual(result.exit_code, 0)
         actual = diff_header.sub(DETERMINISTIC_HEADER, result.output)
@@ -189,22 +228,21 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertEqual(expected, actual)
 
     def test_piping_diff_with_color(self) -> None:
-        source, _ = read_data("expression.py")
-        config = THIS_DIR / "data" / "empty_pyproject.toml"
+        source, _ = read_data("simple_cases", "expression.py")
         args = [
             "-",
             "--fast",
             f"--line-length={black.DEFAULT_LINE_LENGTH}",
             "--diff",
             "--color",
-            f"--config={config}",
+            f"--config={EMPTY_CONFIG}",
         ]
         result = BlackRunner().invoke(
-            black.main, args, input=BytesIO(source.encode("utf8"))
+            black.main, args, input=BytesIO(source.encode("utf-8"))
         )
         actual = result.output
         # Again, the contents are checked in a different test, so only look for colors.
-        self.assertIn("\033[1;37m", actual)
+        self.assertIn("\033[1m", actual)
         self.assertIn("\033[36m", actual)
         self.assertIn("\033[32m", actual)
         self.assertIn("\033[31m", actual)
@@ -212,7 +250,7 @@ class BlackTestCase(BlackBaseTestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def _test_wip(self) -> None:
-        source, expected = read_data("wip")
+        source, expected = read_data("miscellaneous", "wip")
         sys.settrace(tracefunc)
         mode = replace(
             DEFAULT_MODE,
@@ -225,86 +263,29 @@ class BlackTestCase(BlackBaseTestCase):
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, black.FileMode())
 
-    @unittest.expectedFailure
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability1(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens1")
-        actual = fs(source)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @unittest.expectedFailure
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability2(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens2")
-        actual = fs(source)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @unittest.expectedFailure
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability3(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens3")
-        actual = fs(source)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability1_pass2(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens1")
-        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability2_pass2(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens2")
-        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability3_pass2(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens3")
-        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_pep_572(self) -> None:
-        source, expected = read_data("pep_572")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-        if sys.version_info >= (3, 8):
-            black.assert_equivalent(source, actual)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_pep_572_remove_parens(self) -> None:
-        source, expected = read_data("pep_572_remove_parens")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-        if sys.version_info >= (3, 8):
-            black.assert_equivalent(source, actual)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_pep_572_do_not_remove_parens(self) -> None:
-        source, expected = read_data("pep_572_do_not_remove_parens")
-        # the AST safety checks will fail, but that's expected, just make sure no
-        # parentheses are touched
-        actual = black.format_str(source, mode=DEFAULT_MODE)
-        self.assertFormatEqual(expected, actual)
-
     def test_pep_572_version_detection(self) -> None:
-        source, _ = read_data("pep_572")
+        source, _ = read_data("py_38", "pep_572")
         root = black.lib2to3_parse(source)
         features = black.get_features_used(root)
         self.assertIn(black.Feature.ASSIGNMENT_EXPRESSIONS, features)
         versions = black.detect_target_versions(root)
         self.assertIn(black.TargetVersion.PY38, versions)
 
+    def test_pep_695_version_detection(self) -> None:
+        for file in ("type_aliases", "type_params"):
+            source, _ = read_data("py_312", file)
+            root = black.lib2to3_parse(source)
+            features = black.get_features_used(root)
+            self.assertIn(black.Feature.TYPE_PARAMS, features)
+            versions = black.detect_target_versions(root)
+            self.assertIn(black.TargetVersion.PY312, versions)
+
     def test_expression_ff(self) -> None:
-        source, expected = read_data("expression")
+        source, expected = read_data("simple_cases", "expression.py")
         tmp_file = Path(black.dump_to_file(source))
         try:
             self.assertTrue(ff(tmp_file, write_back=black.WriteBack.YES))
-            with open(tmp_file, encoding="utf8") as f:
-                actual = f.read()
+            actual = tmp_file.read_text(encoding="utf-8")
         finally:
             os.unlink(tmp_file)
         self.assertFormatEqual(expected, actual)
@@ -313,17 +294,16 @@ class BlackTestCase(BlackBaseTestCase):
             black.assert_stable(source, actual, DEFAULT_MODE)
 
     def test_expression_diff(self) -> None:
-        source, _ = read_data("expression.py")
-        config = THIS_DIR / "data" / "empty_pyproject.toml"
-        expected, _ = read_data("expression.diff")
+        source, _ = read_data("simple_cases", "expression.py")
+        expected, _ = read_data("simple_cases", "expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         diff_header = re.compile(
             rf"{re.escape(str(tmp_file))}\t\d\d\d\d-\d\d-\d\d "
-            r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
+            r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d\+\d\d:\d\d"
         )
         try:
             result = BlackRunner().invoke(
-                black.main, ["--diff", str(tmp_file), f"--config={config}"]
+                black.main, ["--diff", str(tmp_file), f"--config={EMPTY_CONFIG}"]
             )
             self.assertEqual(result.exit_code, 0)
         finally:
@@ -340,102 +320,101 @@ class BlackTestCase(BlackBaseTestCase):
             self.assertEqual(expected, actual, msg)
 
     def test_expression_diff_with_color(self) -> None:
-        source, _ = read_data("expression.py")
-        config = THIS_DIR / "data" / "empty_pyproject.toml"
-        expected, _ = read_data("expression.diff")
+        source, _ = read_data("simple_cases", "expression.py")
+        expected, _ = read_data("simple_cases", "expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         try:
             result = BlackRunner().invoke(
-                black.main, ["--diff", "--color", str(tmp_file), f"--config={config}"]
+                black.main,
+                ["--diff", "--color", str(tmp_file), f"--config={EMPTY_CONFIG}"],
             )
         finally:
             os.unlink(tmp_file)
         actual = result.output
         # We check the contents of the diff in `test_expression_diff`. All
         # we need to check here is that color codes exist in the result.
-        self.assertIn("\033[1;37m", actual)
+        self.assertIn("\033[1m", actual)
         self.assertIn("\033[36m", actual)
         self.assertIn("\033[32m", actual)
         self.assertIn("\033[31m", actual)
         self.assertIn("\033[0m", actual)
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_pep_570(self) -> None:
-        source, expected = read_data("pep_570")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-        if sys.version_info >= (3, 8):
-            black.assert_equivalent(source, actual)
-
     def test_detect_pos_only_arguments(self) -> None:
-        source, _ = read_data("pep_570")
+        source, _ = read_data("py_38", "pep_570")
         root = black.lib2to3_parse(source)
         features = black.get_features_used(root)
         self.assertIn(black.Feature.POS_ONLY_ARGUMENTS, features)
         versions = black.detect_target_versions(root)
         self.assertIn(black.TargetVersion.PY38, versions)
 
+    def test_detect_debug_f_strings(self) -> None:
+        root = black.lib2to3_parse("""f"{x=}" """)
+        features = black.get_features_used(root)
+        self.assertIn(black.Feature.DEBUG_F_STRINGS, features)
+        versions = black.detect_target_versions(root)
+        self.assertIn(black.TargetVersion.PY38, versions)
+
+        root = black.lib2to3_parse(
+            """f"{x}"\nf'{"="}'\nf'{(x:=5)}'\nf'{f(a="3=")}'\nf'{x:=10}'\n"""
+        )
+        features = black.get_features_used(root)
+        self.assertNotIn(black.Feature.DEBUG_F_STRINGS, features)
+
+        # We don't yet support feature version detection in nested f-strings
+        root = black.lib2to3_parse(
+            """f"heard a rumour that { f'{1+1=}' } ... seems like it could be true" """
+        )
+        features = black.get_features_used(root)
+        self.assertNotIn(black.Feature.DEBUG_F_STRINGS, features)
+
     @patch("black.dump_to_file", dump_to_stderr)
     def test_string_quotes(self) -> None:
-        source, expected = read_data("string_quotes")
-        mode = black.Mode(experimental_string_processing=True)
-        actual = fs(source, mode=mode)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, mode)
+        source, expected = read_data("miscellaneous", "string_quotes")
+        mode = black.Mode(preview=True)
+        assert_format(source, expected, mode)
         mode = replace(mode, string_normalization=False)
         not_normalized = fs(source, mode=mode)
         self.assertFormatEqual(source.replace("\\\n", ""), not_normalized)
         black.assert_equivalent(source, not_normalized)
         black.assert_stable(source, not_normalized, mode=mode)
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_docstring_no_string_normalization(self) -> None:
-        """Like test_docstring but with string normalization off."""
-        source, expected = read_data("docstring_no_string_normalization")
-        mode = replace(DEFAULT_MODE, string_normalization=False)
-        actual = fs(source, mode=mode)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, mode)
-
-    def test_long_strings_flag_disabled(self) -> None:
-        """Tests for turning off the string processing logic."""
-        source, expected = read_data("long_strings_flag_disabled")
-        mode = replace(DEFAULT_MODE, experimental_string_processing=False)
-        actual = fs(source, mode=mode)
-        self.assertFormatEqual(expected, actual)
-        black.assert_stable(expected, actual, mode)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_numeric_literals(self) -> None:
-        source, expected = read_data("numeric_literals")
-        mode = replace(DEFAULT_MODE, target_versions=PY36_VERSIONS)
-        actual = fs(source, mode=mode)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, mode)
+    def test_skip_source_first_line(self) -> None:
+        source, _ = read_data("miscellaneous", "invalid_header")
+        tmp_file = Path(black.dump_to_file(source))
+        # Full source should fail (invalid syntax at header)
+        self.invokeBlack([str(tmp_file), "--diff", "--check"], exit_code=123)
+        # So, skipping the first line should work
+        result = BlackRunner().invoke(
+            black.main, [str(tmp_file), "-x", f"--config={EMPTY_CONFIG}"]
+        )
+        self.assertEqual(result.exit_code, 0)
+        actual = tmp_file.read_text(encoding="utf-8")
+        self.assertFormatEqual(source, actual)
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_numeric_literals_ignoring_underscores(self) -> None:
-        source, expected = read_data("numeric_literals_skip_underscores")
-        mode = replace(DEFAULT_MODE, target_versions=PY36_VERSIONS)
-        actual = fs(source, mode=mode)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, mode)
+    def test_skip_source_first_line_when_mixing_newlines(self) -> None:
+        code_mixing_newlines = b"Header will be skipped\r\ni = [1,2,3]\nj = [1,2,3]\n"
+        expected = b"Header will be skipped\r\ni = [1, 2, 3]\nj = [1, 2, 3]\n"
+        with TemporaryDirectory() as workspace:
+            test_file = Path(workspace) / "skip_header.py"
+            test_file.write_bytes(code_mixing_newlines)
+            mode = replace(DEFAULT_MODE, skip_source_first_line=True)
+            ff(test_file, mode=mode, write_back=black.WriteBack.YES)
+            self.assertEqual(test_file.read_bytes(), expected)
 
     def test_skip_magic_trailing_comma(self) -> None:
-        source, _ = read_data("expression.py")
-        expected, _ = read_data("expression_skip_magic_trailing_comma.diff")
+        source, _ = read_data("simple_cases", "expression")
+        expected, _ = read_data(
+            "miscellaneous", "expression_skip_magic_trailing_comma.diff"
+        )
         tmp_file = Path(black.dump_to_file(source))
         diff_header = re.compile(
             rf"{re.escape(str(tmp_file))}\t\d\d\d\d-\d\d-\d\d "
-            r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
+            r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d\+\d\d:\d\d"
         )
         try:
-            result = BlackRunner().invoke(black.main, ["-C", "--diff", str(tmp_file)])
+            result = BlackRunner().invoke(
+                black.main, ["-C", "--diff", str(tmp_file), f"--config={EMPTY_CONFIG}"]
+            )
             self.assertEqual(result.exit_code, 0)
         finally:
             os.unlink(tmp_file)
@@ -447,64 +426,15 @@ class BlackTestCase(BlackBaseTestCase):
             msg = (
                 "Expected diff isn't equal to the actual. If you made changes to"
                 " expression.py and this is an anticipated difference, overwrite"
-                f" tests/data/expression_skip_magic_trailing_comma.diff with {dump}"
+                " tests/data/miscellaneous/expression_skip_magic_trailing_comma.diff"
+                f" with {dump}"
             )
             self.assertEqual(expected, actual, msg)
 
-    @pytest.mark.no_python2
-    def test_python2_should_fail_without_optional_install(self) -> None:
-        if sys.version_info < (3, 8):
-            self.skipTest(
-                "Python 3.6 and 3.7 will install typed-ast to work and as such will be"
-                " able to parse Python 2 syntax without explicitly specifying the"
-                " python2 extra"
-            )
-
-        source = "x = 1234l"
-        tmp_file = Path(black.dump_to_file(source))
-        try:
-            runner = BlackRunner()
-            result = runner.invoke(black.main, [str(tmp_file)])
-            self.assertEqual(result.exit_code, 123)
-        finally:
-            os.unlink(tmp_file)
-        assert result.stderr_bytes is not None
-        actual = (
-            result.stderr_bytes.decode()
-            .replace("\n", "")
-            .replace("\\n", "")
-            .replace("\\r", "")
-            .replace("\r", "")
-        )
-        msg = (
-            "The requested source code has invalid Python 3 syntax."
-            "If you are trying to format Python 2 files please reinstall Black"
-            " with the 'python2' extra: `python3 -m pip install black[python2]`."
-        )
-        self.assertIn(msg, actual)
-
-    @pytest.mark.python2
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_python2_print_function(self) -> None:
-        source, expected = read_data("python2_print_function")
-        mode = replace(DEFAULT_MODE, target_versions={TargetVersion.PY27})
-        actual = fs(source, mode=mode)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, mode)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_stub(self) -> None:
-        mode = replace(DEFAULT_MODE, is_pyi=True)
-        source, expected = read_data("stub.pyi")
-        actual = fs(source, mode=mode)
-        self.assertFormatEqual(expected, actual)
-        black.assert_stable(source, actual, mode)
-
     @patch("black.dump_to_file", dump_to_stderr)
     def test_async_as_identifier(self) -> None:
-        source_path = (THIS_DIR / "data" / "async_as_identifier.py").resolve()
-        source, expected = read_data("async_as_identifier")
+        source_path = get_case_path("miscellaneous", "async_as_identifier")
+        source, expected = read_data_from_file(source_path)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         major, minor = sys.version_info[:2]
@@ -518,8 +448,8 @@ class BlackTestCase(BlackBaseTestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python37(self) -> None:
-        source_path = (THIS_DIR / "data" / "python37.py").resolve()
-        source, expected = read_data("python37")
+        source_path = get_case_path("py_37", "python37")
+        source, expected = read_data_from_file(source_path)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         major, minor = sys.version_info[:2]
@@ -531,26 +461,6 @@ class BlackTestCase(BlackBaseTestCase):
         # but not on 3.6, because we use async as a reserved keyword
         self.invokeBlack([str(source_path), "--target-version", "py36"], exit_code=123)
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_python38(self) -> None:
-        source, expected = read_data("python38")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        major, minor = sys.version_info[:2]
-        if major > 3 or (major == 3 and minor >= 8):
-            black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_python39(self) -> None:
-        source, expected = read_data("python39")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        major, minor = sys.version_info[:2]
-        if major > 3 or (major == 3 and minor >= 9):
-            black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
     def test_tab_comment_indentation(self) -> None:
         contents_tab = "if 1:\n\tif 2:\n\t\tpass\n\t# comment\n\tpass\n"
         contents_spc = "if 1:\n    if 2:\n        pass\n    # comment\n    pass\n"
@@ -573,6 +483,55 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertFormatEqual(contents_spc, fs(contents_spc))
         self.assertFormatEqual(contents_spc, fs(contents_tab))
 
+    def test_false_positive_symlink_output_issue_3384(self) -> None:
+        # Emulate the behavior when using the CLI (`black ./child  --verbose`), which
+        # involves patching some `pathlib.Path` methods. In particular, `is_dir` is
+        # patched only on its first call: when checking if "./child" is a directory it
+        # should return True. The "./child" folder exists relative to the cwd when
+        # running from CLI, but fails when running the tests because cwd is different
+        project_root = Path(THIS_DIR / "data" / "nested_gitignore_tests")
+        working_directory = project_root / "root"
+        target_abspath = working_directory / "child"
+        target_contents = (
+            src.relative_to(working_directory) for src in target_abspath.iterdir()
+        )
+
+        def mock_n_calls(responses: List[bool]) -> Callable[[], bool]:
+            def _mocked_calls() -> bool:
+                if responses:
+                    return responses.pop(0)
+                return False
+
+            return _mocked_calls
+
+        with patch("pathlib.Path.iterdir", return_value=target_contents), patch(
+            "pathlib.Path.cwd", return_value=working_directory
+        ), patch("pathlib.Path.is_dir", side_effect=mock_n_calls([True])):
+            ctx = FakeContext()
+            # Note that the root folder (project_root) isn't the folder
+            # named "root" (aka working_directory)
+            ctx.obj["root"] = project_root
+            report = MagicMock(verbose=True)
+            black.get_sources(
+                ctx=ctx,
+                src=("./child",),
+                quiet=False,
+                verbose=True,
+                include=DEFAULT_INCLUDE,
+                exclude=None,
+                report=report,
+                extend_exclude=None,
+                force_exclude=None,
+                stdin_filename=None,
+            )
+        assert not any(
+            mock_args[1].startswith("is a symbolic link that points outside")
+            for _, mock_args, _ in report.path_ignored.mock_calls
+        ), "A symbolic link was reported."
+        report.path_ignored.assert_called_once_with(
+            Path("root", "child", "b.py"), "matches a .gitignore file content"
+        )
+
     def test_report_verbose(self) -> None:
         report = Report(verbose=True)
         out_lines = []
@@ -664,15 +623,15 @@ class BlackTestCase(BlackBaseTestCase):
             report.check = True
             self.assertEqual(
                 unstyle(str(report)),
-                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
-                " would fail to reformat.",
+                "2 files would be reformatted, 3 files would be left unchanged, 2"
+                " files would fail to reformat.",
             )
             report.check = False
             report.diff = True
             self.assertEqual(
                 unstyle(str(report)),
-                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
-                " would fail to reformat.",
+                "2 files would be reformatted, 3 files would be left unchanged, 2"
+                " files would fail to reformat.",
             )
 
     def test_report_quiet(self) -> None:
@@ -758,15 +717,15 @@ class BlackTestCase(BlackBaseTestCase):
             report.check = True
             self.assertEqual(
                 unstyle(str(report)),
-                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
-                " would fail to reformat.",
+                "2 files would be reformatted, 3 files would be left unchanged, 2"
+                " files would fail to reformat.",
             )
             report.check = False
             report.diff = True
             self.assertEqual(
                 unstyle(str(report)),
-                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
-                " would fail to reformat.",
+                "2 files would be reformatted, 3 files would be left unchanged, 2"
+                " files would fail to reformat.",
             )
 
     def test_report_normal(self) -> None:
@@ -855,15 +814,15 @@ class BlackTestCase(BlackBaseTestCase):
             report.check = True
             self.assertEqual(
                 unstyle(str(report)),
-                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
-                " would fail to reformat.",
+                "2 files would be reformatted, 3 files would be left unchanged, 2"
+                " files would fail to reformat.",
             )
             report.check = False
             report.diff = True
             self.assertEqual(
                 unstyle(str(report)),
-                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
-                " would fail to reformat.",
+                "2 files would be reformatted, 3 files would be left unchanged, 2"
+                " files would fail to reformat.",
             )
 
     def test_lib2to3_parse(self) -> None:
@@ -872,31 +831,22 @@ class BlackTestCase(BlackBaseTestCase):
 
         straddling = "x + y"
         black.lib2to3_parse(straddling)
-        black.lib2to3_parse(straddling, {TargetVersion.PY27})
         black.lib2to3_parse(straddling, {TargetVersion.PY36})
-        black.lib2to3_parse(straddling, {TargetVersion.PY27, TargetVersion.PY36})
 
         py2_only = "print x"
-        black.lib2to3_parse(py2_only)
-        black.lib2to3_parse(py2_only, {TargetVersion.PY27})
         with self.assertRaises(black.InvalidInput):
             black.lib2to3_parse(py2_only, {TargetVersion.PY36})
-        with self.assertRaises(black.InvalidInput):
-            black.lib2to3_parse(py2_only, {TargetVersion.PY27, TargetVersion.PY36})
 
         py3_only = "exec(x, end=y)"
         black.lib2to3_parse(py3_only)
-        with self.assertRaises(black.InvalidInput):
-            black.lib2to3_parse(py3_only, {TargetVersion.PY27})
         black.lib2to3_parse(py3_only, {TargetVersion.PY36})
-        black.lib2to3_parse(py3_only, {TargetVersion.PY27, TargetVersion.PY36})
 
     def test_get_features_used_decorator(self) -> None:
         # Test the feature detection of new decorator syntax
         # since this makes some test cases of test_get_features_used()
         # fails if it fails, this is tested first so that a useful case
         # is identified
-        simples, relaxed = read_data("decorators")
+        simples, relaxed = read_data("miscellaneous", "decorators")
         # skip explanation comments at the top of the file
         for simple_test in simples.split("##")[1:]:
             node = black.lib2to3_parse(simple_test)
@@ -939,7 +889,7 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertEqual(black.get_features_used(node), {Feature.NUMERIC_UNDERSCORES})
         node = black.lib2to3_parse("123456\n")
         self.assertEqual(black.get_features_used(node), set())
-        source, expected = read_data("function")
+        source, expected = read_data("simple_cases", "function")
         node = black.lib2to3_parse(source)
         expected_features = {
             Feature.TRAILING_COMMA_IN_CALL,
@@ -949,11 +899,65 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertEqual(black.get_features_used(node), expected_features)
         node = black.lib2to3_parse(expected)
         self.assertEqual(black.get_features_used(node), expected_features)
-        source, expected = read_data("expression")
+        source, expected = read_data("simple_cases", "expression")
         node = black.lib2to3_parse(source)
         self.assertEqual(black.get_features_used(node), set())
         node = black.lib2to3_parse(expected)
         self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("lambda a, /, b: ...")
+        self.assertEqual(black.get_features_used(node), {Feature.POS_ONLY_ARGUMENTS})
+        node = black.lib2to3_parse("def fn(a, /, b): ...")
+        self.assertEqual(black.get_features_used(node), {Feature.POS_ONLY_ARGUMENTS})
+        node = black.lib2to3_parse("def fn(): yield a, b")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("def fn(): return a, b")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("def fn(): yield *b, c")
+        self.assertEqual(black.get_features_used(node), {Feature.UNPACKING_ON_FLOW})
+        node = black.lib2to3_parse("def fn(): return a, *b, c")
+        self.assertEqual(black.get_features_used(node), {Feature.UNPACKING_ON_FLOW})
+        node = black.lib2to3_parse("x = a, *b, c")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("x: Any = regular")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("x: Any = (regular, regular)")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("x: Any = Complex(Type(1))[something]")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("x: Tuple[int, ...] = a, b, c")
+        self.assertEqual(
+            black.get_features_used(node), {Feature.ANN_ASSIGN_EXTENDED_RHS}
+        )
+        node = black.lib2to3_parse("try: pass\nexcept Something: pass")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("try: pass\nexcept (*Something,): pass")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("try: pass\nexcept *Group: pass")
+        self.assertEqual(black.get_features_used(node), {Feature.EXCEPT_STAR})
+        node = black.lib2to3_parse("a[*b]")
+        self.assertEqual(black.get_features_used(node), {Feature.VARIADIC_GENERICS})
+        node = black.lib2to3_parse("a[x, *y(), z] = t")
+        self.assertEqual(black.get_features_used(node), {Feature.VARIADIC_GENERICS})
+        node = black.lib2to3_parse("def fn(*args: *T): pass")
+        self.assertEqual(black.get_features_used(node), {Feature.VARIADIC_GENERICS})
+
+    def test_get_features_used_for_future_flags(self) -> None:
+        for src, features in [
+            ("from __future__ import annotations", {Feature.FUTURE_ANNOTATIONS}),
+            (
+                "from __future__ import (other, annotations)",
+                {Feature.FUTURE_ANNOTATIONS},
+            ),
+            ("a = 1 + 2\nfrom something import annotations", set()),
+            ("from __future__ import x, y", set()),
+        ]:
+            with self.subTest(src=src, features=features):
+                node = black.lib2to3_parse(src)
+                future_imports = black.get_future_imports(node)
+                self.assertEqual(
+                    black.get_features_used(node, future_imports=future_imports),
+                    features,
+                )
 
     def test_get_future_imports(self) -> None:
         node = black.lib2to3_parse("\n")
@@ -985,9 +989,10 @@ class BlackTestCase(BlackBaseTestCase):
         )
         self.assertEqual({"unicode_literals", "print"}, black.get_future_imports(node))
 
+    @pytest.mark.incompatible_with_mypyc
     def test_debug_visitor(self) -> None:
-        source, _ = read_data("debug_visitor.py")
-        expected, _ = read_data("debug_visitor.out")
+        source, _ = read_data("miscellaneous", "debug_visitor")
+        expected, _ = read_data("miscellaneous", "debug_visitor.out")
         out_lines = []
         err_lines = []
 
@@ -1010,8 +1015,8 @@ class BlackTestCase(BlackBaseTestCase):
         )
 
     def test_format_file_contents(self) -> None:
-        empty = ""
         mode = DEFAULT_MODE
+        empty = ""
         with self.assertRaises(black.NothingChanged):
             black.format_file_contents(empty, mode=mode, fast=False)
         just_nl = "\n"
@@ -1029,12 +1034,24 @@ class BlackTestCase(BlackBaseTestCase):
             black.format_file_contents(invalid, mode=mode, fast=False)
         self.assertEqual(str(e.exception), "Cannot parse: 1:7: return if you can")
 
+        mode = black.Mode(preview=True)
+        just_crlf = "\r\n"
+        with self.assertRaises(black.NothingChanged):
+            black.format_file_contents(just_crlf, mode=mode, fast=False)
+        just_whitespace_nl = "\n\t\n \n\t \n \t\n\n"
+        actual = black.format_file_contents(just_whitespace_nl, mode=mode, fast=False)
+        self.assertEqual("\n", actual)
+        just_whitespace_crlf = "\r\n\t\r\n \r\n\t \r\n \t\r\n\r\n"
+        actual = black.format_file_contents(just_whitespace_crlf, mode=mode, fast=False)
+        self.assertEqual("\r\n", actual)
+
     def test_endmarker(self) -> None:
         n = black.lib2to3_parse("\n")
         self.assertEqual(n.type, black.syms.file_input)
         self.assertEqual(len(n.children), 1)
         self.assertEqual(n.children[0].type, black.token.ENDMARKER)
 
+    @pytest.mark.incompatible_with_mypyc
     @unittest.skipIf(os.environ.get("SKIP_AST_PRINT"), "user set SKIP_AST_PRINT")
     def test_assertFormatEqual(self) -> None:
         out_lines = []
@@ -1051,246 +1068,58 @@ class BlackTestCase(BlackBaseTestCase):
                 self.assertFormatEqual("j = [1, 2, 3]", "j = [1, 2, 3,]")
 
         out_str = "".join(out_lines)
-        self.assertTrue("Expected tree:" in out_str)
-        self.assertTrue("Actual tree:" in out_str)
+        self.assertIn("Expected tree:", out_str)
+        self.assertIn("Actual tree:", out_str)
         self.assertEqual("".join(err_lines), "")
 
-    def test_cache_broken_file(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir() as workspace:
-            cache_file = get_cache_file(mode)
-            with cache_file.open("w") as fobj:
-                fobj.write("this is not a pickle")
-            self.assertEqual(black.read_cache(mode), {})
-            src = (workspace / "test.py").resolve()
-            with src.open("w") as fobj:
-                fobj.write("print('hello')")
-            self.invokeBlack([str(src)])
-            cache = black.read_cache(mode)
-            self.assertIn(str(src), cache)
-
-    def test_cache_single_file_already_cached(self) -> None:
-        mode = DEFAULT_MODE
+    @event_loop()
+    @patch("concurrent.futures.ProcessPoolExecutor", MagicMock(side_effect=OSError))
+    def test_works_in_mono_process_only_environment(self) -> None:
         with cache_dir() as workspace:
-            src = (workspace / "test.py").resolve()
-            with src.open("w") as fobj:
-                fobj.write("print('hello')")
-            black.write_cache({}, [src], mode)
-            self.invokeBlack([str(src)])
-            with src.open("r") as fobj:
-                self.assertEqual(fobj.read(), "print('hello')")
+            for f in [
+                (workspace / "one.py").resolve(),
+                (workspace / "two.py").resolve(),
+            ]:
+                f.write_text('print("hello")\n', encoding="utf-8")
+            self.invokeBlack([str(workspace)])
 
     @event_loop()
-    def test_cache_multiple_files(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir() as workspace, patch(
-            "black.ProcessPoolExecutor", new=ThreadPoolExecutor
-        ):
-            one = (workspace / "one.py").resolve()
-            with one.open("w") as fobj:
-                fobj.write("print('hello')")
-            two = (workspace / "two.py").resolve()
-            with two.open("w") as fobj:
-                fobj.write("print('hello')")
-            black.write_cache({}, [one], mode)
-            self.invokeBlack([str(workspace)])
-            with one.open("r") as fobj:
-                self.assertEqual(fobj.read(), "print('hello')")
-            with two.open("r") as fobj:
-                self.assertEqual(fobj.read(), 'print("hello")\n')
-            cache = black.read_cache(mode)
-            self.assertIn(str(one), cache)
-            self.assertIn(str(two), cache)
+    def test_check_diff_use_together(self) -> None:
+        with cache_dir():
+            # Files which will be reformatted.
+            src1 = get_case_path("miscellaneous", "string_quotes")
+            self.invokeBlack([str(src1), "--diff", "--check"], exit_code=1)
+            # Files which will not be reformatted.
+            src2 = get_case_path("simple_cases", "composition")
+            self.invokeBlack([str(src2), "--diff", "--check"])
+            # Multi file command.
+            self.invokeBlack([str(src1), str(src2), "--diff", "--check"], exit_code=1)
 
-    def test_no_cache_when_writeback_diff(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir() as workspace:
-            src = (workspace / "test.py").resolve()
-            with src.open("w") as fobj:
-                fobj.write("print('hello')")
-            with patch("black.read_cache") as read_cache, patch(
-                "black.write_cache"
-            ) as write_cache:
-                self.invokeBlack([str(src), "--diff"])
-                cache_file = get_cache_file(mode)
-                self.assertFalse(cache_file.exists())
-                write_cache.assert_not_called()
-                read_cache.assert_not_called()
+    def test_no_src_fails(self) -> None:
+        with cache_dir():
+            self.invokeBlack([], exit_code=1)
 
-    def test_no_cache_when_writeback_color_diff(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir() as workspace:
-            src = (workspace / "test.py").resolve()
-            with src.open("w") as fobj:
-                fobj.write("print('hello')")
-            with patch("black.read_cache") as read_cache, patch(
-                "black.write_cache"
-            ) as write_cache:
-                self.invokeBlack([str(src), "--diff", "--color"])
-                cache_file = get_cache_file(mode)
-                self.assertFalse(cache_file.exists())
-                write_cache.assert_not_called()
-                read_cache.assert_not_called()
-
-    @event_loop()
-    def test_output_locking_when_writeback_diff(self) -> None:
-        with cache_dir() as workspace:
-            for tag in range(0, 4):
-                src = (workspace / f"test{tag}.py").resolve()
-                with src.open("w") as fobj:
-                    fobj.write("print('hello')")
-            with patch("black.Manager", wraps=multiprocessing.Manager) as mgr:
-                self.invokeBlack(["--diff", str(workspace)], exit_code=0)
-                # this isn't quite doing what we want, but if it _isn't_
-                # called then we cannot be using the lock it provides
-                mgr.assert_called()
-
-    @event_loop()
-    def test_output_locking_when_writeback_color_diff(self) -> None:
-        with cache_dir() as workspace:
-            for tag in range(0, 4):
-                src = (workspace / f"test{tag}.py").resolve()
-                with src.open("w") as fobj:
-                    fobj.write("print('hello')")
-            with patch("black.Manager", wraps=multiprocessing.Manager) as mgr:
-                self.invokeBlack(["--diff", "--color", str(workspace)], exit_code=0)
-                # this isn't quite doing what we want, but if it _isn't_
-                # called then we cannot be using the lock it provides
-                mgr.assert_called()
-
-    def test_no_cache_when_stdin(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir():
-            result = CliRunner().invoke(
-                black.main, ["-"], input=BytesIO(b"print('hello')")
-            )
-            self.assertEqual(result.exit_code, 0)
-            cache_file = get_cache_file(mode)
-            self.assertFalse(cache_file.exists())
-
-    def test_read_cache_no_cachefile(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir():
-            self.assertEqual(black.read_cache(mode), {})
-
-    def test_write_cache_read_cache(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir() as workspace:
-            src = (workspace / "test.py").resolve()
-            src.touch()
-            black.write_cache({}, [src], mode)
-            cache = black.read_cache(mode)
-            self.assertIn(str(src), cache)
-            self.assertEqual(cache[str(src)], black.get_cache_info(src))
-
-    def test_filter_cached(self) -> None:
-        with TemporaryDirectory() as workspace:
-            path = Path(workspace)
-            uncached = (path / "uncached").resolve()
-            cached = (path / "cached").resolve()
-            cached_but_changed = (path / "changed").resolve()
-            uncached.touch()
-            cached.touch()
-            cached_but_changed.touch()
-            cache = {
-                str(cached): black.get_cache_info(cached),
-                str(cached_but_changed): (0.0, 0),
-            }
-            todo, done = black.filter_cached(
-                cache, {uncached, cached, cached_but_changed}
-            )
-            self.assertEqual(todo, {uncached, cached_but_changed})
-            self.assertEqual(done, {cached})
-
-    def test_write_cache_creates_directory_if_needed(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir(exists=False) as workspace:
-            self.assertFalse(workspace.exists())
-            black.write_cache({}, [], mode)
-            self.assertTrue(workspace.exists())
-
-    @event_loop()
-    def test_failed_formatting_does_not_get_cached(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir() as workspace, patch(
-            "black.ProcessPoolExecutor", new=ThreadPoolExecutor
-        ):
-            failing = (workspace / "failing.py").resolve()
-            with failing.open("w") as fobj:
-                fobj.write("not actually python")
-            clean = (workspace / "clean.py").resolve()
-            with clean.open("w") as fobj:
-                fobj.write('print("hello")\n')
-            self.invokeBlack([str(workspace)], exit_code=123)
-            cache = black.read_cache(mode)
-            self.assertNotIn(str(failing), cache)
-            self.assertIn(str(clean), cache)
-
-    def test_write_cache_write_fail(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir(), patch.object(Path, "open") as mock:
-            mock.side_effect = OSError
-            black.write_cache({}, [], mode)
-
-    @event_loop()
-    @patch("black.ProcessPoolExecutor", MagicMock(side_effect=OSError))
-    def test_works_in_mono_process_only_environment(self) -> None:
-        with cache_dir() as workspace:
-            for f in [
-                (workspace / "one.py").resolve(),
-                (workspace / "two.py").resolve(),
-            ]:
-                f.write_text('print("hello")\n')
-            self.invokeBlack([str(workspace)])
-
-    @event_loop()
-    def test_check_diff_use_together(self) -> None:
-        with cache_dir():
-            # Files which will be reformatted.
-            src1 = (THIS_DIR / "data" / "string_quotes.py").resolve()
-            self.invokeBlack([str(src1), "--diff", "--check"], exit_code=1)
-            # Files which will not be reformatted.
-            src2 = (THIS_DIR / "data" / "composition.py").resolve()
-            self.invokeBlack([str(src2), "--diff", "--check"])
-            # Multi file command.
-            self.invokeBlack([str(src1), str(src2), "--diff", "--check"], exit_code=1)
-
-    def test_no_files(self) -> None:
-        with cache_dir():
-            # Without an argument, black exits with error code 0.
-            self.invokeBlack([])
+    def test_src_and_code_fails(self) -> None:
+        with cache_dir():
+            self.invokeBlack([".", "-c", "0"], exit_code=1)
 
     def test_broken_symlink(self) -> None:
         with cache_dir() as workspace:
             symlink = workspace / "broken_link.py"
             try:
                 symlink.symlink_to("nonexistent.py")
-            except OSError as e:
+            except (OSError, NotImplementedError) as e:
                 self.skipTest(f"Can't create symlinks: {e}")
             self.invokeBlack([str(workspace.resolve())])
 
-    def test_read_cache_line_lengths(self) -> None:
-        mode = DEFAULT_MODE
-        short_mode = replace(DEFAULT_MODE, line_length=1)
-        with cache_dir() as workspace:
-            path = (workspace / "file.py").resolve()
-            path.touch()
-            black.write_cache({}, [path], mode)
-            one = black.read_cache(mode)
-            self.assertIn(str(path), one)
-            two = black.read_cache(short_mode)
-            self.assertNotIn(str(path), two)
-
     def test_single_file_force_pyi(self) -> None:
         pyi_mode = replace(DEFAULT_MODE, is_pyi=True)
-        contents, expected = read_data("force_pyi")
+        contents, expected = read_data("miscellaneous", "force_pyi")
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()
-            with open(path, "w") as fh:
-                fh.write(contents)
+            path.write_text(contents, encoding="utf-8")
             self.invokeBlack([str(path), "--pyi"])
-            with open(path, "r") as fh:
-                actual = fh.read()
+            actual = path.read_text(encoding="utf-8")
             # verify cache with --pyi is separate
             pyi_cache = black.read_cache(pyi_mode)
             self.assertIn(str(path), pyi_cache)
@@ -1304,19 +1133,17 @@ class BlackTestCase(BlackBaseTestCase):
     def test_multi_file_force_pyi(self) -> None:
         reg_mode = DEFAULT_MODE
         pyi_mode = replace(DEFAULT_MODE, is_pyi=True)
-        contents, expected = read_data("force_pyi")
+        contents, expected = read_data("miscellaneous", "force_pyi")
         with cache_dir() as workspace:
             paths = [
                 (workspace / "file1.py").resolve(),
                 (workspace / "file2.py").resolve(),
             ]
             for path in paths:
-                with open(path, "w") as fh:
-                    fh.write(contents)
+                path.write_text(contents, encoding="utf-8")
             self.invokeBlack([str(p) for p in paths] + ["--pyi"])
             for path in paths:
-                with open(path, "r") as fh:
-                    actual = fh.read()
+                actual = path.read_text(encoding="utf-8")
                 self.assertEqual(actual, expected)
             # verify cache with --pyi is separate
             pyi_cache = black.read_cache(pyi_mode)
@@ -1326,9 +1153,9 @@ class BlackTestCase(BlackBaseTestCase):
                 self.assertNotIn(str(path), normal_cache)
 
     def test_pipe_force_pyi(self) -> None:
-        source, expected = read_data("force_pyi")
+        source, expected = read_data("miscellaneous", "force_pyi")
         result = CliRunner().invoke(
-            black.main, ["-", "-q", "--pyi"], input=BytesIO(source.encode("utf8"))
+            black.main, ["-", "-q", "--pyi"], input=BytesIO(source.encode("utf-8"))
         )
         self.assertEqual(result.exit_code, 0)
         actual = result.output
@@ -1337,14 +1164,12 @@ class BlackTestCase(BlackBaseTestCase):
     def test_single_file_force_py36(self) -> None:
         reg_mode = DEFAULT_MODE
         py36_mode = replace(DEFAULT_MODE, target_versions=PY36_VERSIONS)
-        source, expected = read_data("force_py36")
+        source, expected = read_data("miscellaneous", "force_py36")
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()
-            with open(path, "w") as fh:
-                fh.write(source)
+            path.write_text(source, encoding="utf-8")
             self.invokeBlack([str(path), *PY36_ARGS])
-            with open(path, "r") as fh:
-                actual = fh.read()
+            actual = path.read_text(encoding="utf-8")
             # verify cache with --target-version is separate
             py36_cache = black.read_cache(py36_mode)
             self.assertIn(str(path), py36_cache)
@@ -1356,19 +1181,17 @@ class BlackTestCase(BlackBaseTestCase):
     def test_multi_file_force_py36(self) -> None:
         reg_mode = DEFAULT_MODE
         py36_mode = replace(DEFAULT_MODE, target_versions=PY36_VERSIONS)
-        source, expected = read_data("force_py36")
+        source, expected = read_data("miscellaneous", "force_py36")
         with cache_dir() as workspace:
             paths = [
                 (workspace / "file1.py").resolve(),
                 (workspace / "file2.py").resolve(),
             ]
             for path in paths:
-                with open(path, "w") as fh:
-                    fh.write(source)
+                path.write_text(source, encoding="utf-8")
             self.invokeBlack([str(p) for p in paths] + PY36_ARGS)
             for path in paths:
-                with open(path, "r") as fh:
-                    actual = fh.read()
+                actual = path.read_text(encoding="utf-8")
                 self.assertEqual(actual, expected)
             # verify cache with --target-version is separate
             pyi_cache = black.read_cache(py36_mode)
@@ -1378,224 +1201,17 @@ class BlackTestCase(BlackBaseTestCase):
                 self.assertNotIn(str(path), normal_cache)
 
     def test_pipe_force_py36(self) -> None:
-        source, expected = read_data("force_py36")
+        source, expected = read_data("miscellaneous", "force_py36")
         result = CliRunner().invoke(
             black.main,
             ["-", "-q", "--target-version=py36"],
-            input=BytesIO(source.encode("utf8")),
+            input=BytesIO(source.encode("utf-8")),
         )
         self.assertEqual(result.exit_code, 0)
         actual = result.output
         self.assertFormatEqual(actual, expected)
 
-    def test_include_exclude(self) -> None:
-        path = THIS_DIR / "data" / "include_exclude_tests"
-        include = re.compile(r"\.pyi?$")
-        exclude = re.compile(r"/exclude/|/\.definitely_exclude/")
-        report = black.Report()
-        gitignore = PathSpec.from_lines("gitwildmatch", [])
-        sources: List[Path] = []
-        expected = [
-            Path(path / "b/dont_exclude/a.py"),
-            Path(path / "b/dont_exclude/a.pyi"),
-        ]
-        this_abs = THIS_DIR.resolve()
-        sources.extend(
-            black.gen_python_files(
-                path.iterdir(),
-                this_abs,
-                include,
-                exclude,
-                None,
-                None,
-                report,
-                gitignore,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    def test_gitignore_used_as_default(self) -> None:
-        path = Path(THIS_DIR / "data" / "include_exclude_tests")
-        include = re.compile(r"\.pyi?$")
-        extend_exclude = re.compile(r"/exclude/")
-        src = str(path / "b/")
-        report = black.Report()
-        expected: List[Path] = [
-            path / "b/.definitely_exclude/a.py",
-            path / "b/.definitely_exclude/a.pyi",
-        ]
-        sources = list(
-            black.get_sources(
-                ctx=FakeContext(),
-                src=(src,),
-                quiet=True,
-                verbose=False,
-                include=include,
-                exclude=None,
-                extend_exclude=extend_exclude,
-                force_exclude=None,
-                report=report,
-                stdin_filename=None,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
-    def test_exclude_for_issue_1572(self) -> None:
-        # Exclude shouldn't touch files that were explicitly given to Black through the
-        # CLI. Exclude is supposed to only apply to the recursive discovery of files.
-        # https://github.com/psf/black/issues/1572
-        path = THIS_DIR / "data" / "include_exclude_tests"
-        include = ""
-        exclude = r"/exclude/|a\.py"
-        src = str(path / "b/exclude/a.py")
-        report = black.Report()
-        expected = [Path(path / "b/exclude/a.py")]
-        sources = list(
-            black.get_sources(
-                ctx=FakeContext(),
-                src=(src,),
-                quiet=True,
-                verbose=False,
-                include=re.compile(include),
-                exclude=re.compile(exclude),
-                extend_exclude=None,
-                force_exclude=None,
-                report=report,
-                stdin_filename=None,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
-    def test_get_sources_with_stdin(self) -> None:
-        include = ""
-        exclude = r"/exclude/|a\.py"
-        src = "-"
-        report = black.Report()
-        expected = [Path("-")]
-        sources = list(
-            black.get_sources(
-                ctx=FakeContext(),
-                src=(src,),
-                quiet=True,
-                verbose=False,
-                include=re.compile(include),
-                exclude=re.compile(exclude),
-                extend_exclude=None,
-                force_exclude=None,
-                report=report,
-                stdin_filename=None,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
-    def test_get_sources_with_stdin_filename(self) -> None:
-        include = ""
-        exclude = r"/exclude/|a\.py"
-        src = "-"
-        report = black.Report()
-        stdin_filename = str(THIS_DIR / "data/collections.py")
-        expected = [Path(f"__BLACK_STDIN_FILENAME__{stdin_filename}")]
-        sources = list(
-            black.get_sources(
-                ctx=FakeContext(),
-                src=(src,),
-                quiet=True,
-                verbose=False,
-                include=re.compile(include),
-                exclude=re.compile(exclude),
-                extend_exclude=None,
-                force_exclude=None,
-                report=report,
-                stdin_filename=stdin_filename,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
-    def test_get_sources_with_stdin_filename_and_exclude(self) -> None:
-        # Exclude shouldn't exclude stdin_filename since it is mimicking the
-        # file being passed directly. This is the same as
-        # test_exclude_for_issue_1572
-        path = THIS_DIR / "data" / "include_exclude_tests"
-        include = ""
-        exclude = r"/exclude/|a\.py"
-        src = "-"
-        report = black.Report()
-        stdin_filename = str(path / "b/exclude/a.py")
-        expected = [Path(f"__BLACK_STDIN_FILENAME__{stdin_filename}")]
-        sources = list(
-            black.get_sources(
-                ctx=FakeContext(),
-                src=(src,),
-                quiet=True,
-                verbose=False,
-                include=re.compile(include),
-                exclude=re.compile(exclude),
-                extend_exclude=None,
-                force_exclude=None,
-                report=report,
-                stdin_filename=stdin_filename,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
-    def test_get_sources_with_stdin_filename_and_extend_exclude(self) -> None:
-        # Extend exclude shouldn't exclude stdin_filename since it is mimicking the
-        # file being passed directly. This is the same as
-        # test_exclude_for_issue_1572
-        path = THIS_DIR / "data" / "include_exclude_tests"
-        include = ""
-        extend_exclude = r"/exclude/|a\.py"
-        src = "-"
-        report = black.Report()
-        stdin_filename = str(path / "b/exclude/a.py")
-        expected = [Path(f"__BLACK_STDIN_FILENAME__{stdin_filename}")]
-        sources = list(
-            black.get_sources(
-                ctx=FakeContext(),
-                src=(src,),
-                quiet=True,
-                verbose=False,
-                include=re.compile(include),
-                exclude=re.compile(""),
-                extend_exclude=re.compile(extend_exclude),
-                force_exclude=None,
-                report=report,
-                stdin_filename=stdin_filename,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
-    def test_get_sources_with_stdin_filename_and_force_exclude(self) -> None:
-        # Force exclude should exclude the file when passing it through
-        # stdin_filename
-        path = THIS_DIR / "data" / "include_exclude_tests"
-        include = ""
-        force_exclude = r"/exclude/|a\.py"
-        src = "-"
-        report = black.Report()
-        stdin_filename = str(path / "b/exclude/a.py")
-        sources = list(
-            black.get_sources(
-                ctx=FakeContext(),
-                src=(src,),
-                quiet=True,
-                verbose=False,
-                include=re.compile(include),
-                exclude=re.compile(""),
-                extend_exclude=None,
-                force_exclude=re.compile(force_exclude),
-                report=report,
-                stdin_filename=stdin_filename,
-            )
-        )
-        self.assertEqual([], sorted(sources))
-
+    @pytest.mark.incompatible_with_mypyc
     def test_reformat_one_with_stdin(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",
@@ -1613,6 +1229,7 @@ class BlackTestCase(BlackBaseTestCase):
             fsts.assert_called_once()
             report.done.assert_called_with(path, black.Changed.YES)
 
+    @pytest.mark.incompatible_with_mypyc
     def test_reformat_one_with_stdin_filename(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",
@@ -1635,6 +1252,7 @@ class BlackTestCase(BlackBaseTestCase):
             # __BLACK_STDIN_FILENAME__ should have been stripped
             report.done.assert_called_with(expected, black.Changed.YES)
 
+    @pytest.mark.incompatible_with_mypyc
     def test_reformat_one_with_stdin_filename_pyi(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",
@@ -1659,6 +1277,32 @@ class BlackTestCase(BlackBaseTestCase):
             # __BLACK_STDIN_FILENAME__ should have been stripped
             report.done.assert_called_with(expected, black.Changed.YES)
 
+    @pytest.mark.incompatible_with_mypyc
+    def test_reformat_one_with_stdin_filename_ipynb(self) -> None:
+        with patch(
+            "black.format_stdin_to_stdout",
+            return_value=lambda *args, **kwargs: black.Changed.YES,
+        ) as fsts:
+            report = MagicMock()
+            p = "foo.ipynb"
+            path = Path(f"__BLACK_STDIN_FILENAME__{p}")
+            expected = Path(p)
+            black.reformat_one(
+                path,
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=DEFAULT_MODE,
+                report=report,
+            )
+            fsts.assert_called_once_with(
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=replace(DEFAULT_MODE, is_ipynb=True),
+            )
+            # __BLACK_STDIN_FILENAME__ should have been stripped
+            report.done.assert_called_with(expected, black.Changed.YES)
+
+    @pytest.mark.incompatible_with_mypyc
     def test_reformat_one_with_stdin_and_existing_path(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",
@@ -1667,7 +1311,7 @@ class BlackTestCase(BlackBaseTestCase):
             report = MagicMock()
             # Even with an existing file, since we are forcing stdin, black
             # should output to stdout and not modify the file inplace
-            p = Path(str(THIS_DIR / "data/collections.py"))
+            p = THIS_DIR / "data" / "simple_cases" / "collections.py"
             # Make sure is_file actually returns True
             self.assertTrue(p.is_file())
             path = Path(f"__BLACK_STDIN_FILENAME__{p}")
@@ -1684,8 +1328,51 @@ class BlackTestCase(BlackBaseTestCase):
             report.done.assert_called_with(expected, black.Changed.YES)
 
     def test_reformat_one_with_stdin_empty(self) -> None:
+        cases = [
+            ("", ""),
+            ("\n", "\n"),
+            ("\r\n", "\r\n"),
+            (" \t", ""),
+            (" \t\n\t ", "\n"),
+            (" \t\r\n\t ", "\r\n"),
+        ]
+
+        def _new_wrapper(
+            output: io.StringIO, io_TextIOWrapper: Type[io.TextIOWrapper]
+        ) -> Callable[[Any, Any], io.TextIOWrapper]:
+            def get_output(*args: Any, **kwargs: Any) -> io.TextIOWrapper:
+                if args == (sys.stdout.buffer,):
+                    # It's `format_stdin_to_stdout()` calling `io.TextIOWrapper()`,
+                    # return our mock object.
+                    return output
+                # It's something else (i.e. `decode_bytes()`) calling
+                # `io.TextIOWrapper()`, pass through to the original implementation.
+                # See discussion in https://github.com/psf/black/pull/2489
+                return io_TextIOWrapper(*args, **kwargs)
+
+            return get_output
+
+        mode = black.Mode(preview=True)
+        for content, expected in cases:
+            output = io.StringIO()
+            io_TextIOWrapper = io.TextIOWrapper
+
+            with patch("io.TextIOWrapper", _new_wrapper(output, io_TextIOWrapper)):
+                try:
+                    black.format_stdin_to_stdout(
+                        fast=True,
+                        content=content,
+                        write_back=black.WriteBack.YES,
+                        mode=mode,
+                    )
+                except io.UnsupportedOperation:
+                    pass  # StringIO does not support detach
+                assert output.getvalue() == expected
+
+        # An empty string is the only test case for `preview=False`
         output = io.StringIO()
-        with patch("io.TextIOWrapper", lambda *args, **kwargs: output):
+        io_TextIOWrapper = io.TextIOWrapper
+        with patch("io.TextIOWrapper", _new_wrapper(output, io_TextIOWrapper)):
             try:
                 black.format_stdin_to_stdout(
                     fast=True,
@@ -1697,132 +1384,38 @@ class BlackTestCase(BlackBaseTestCase):
                 pass  # StringIO does not support detach
             assert output.getvalue() == ""
 
-    def test_gitignore_exclude(self) -> None:
-        path = THIS_DIR / "data" / "include_exclude_tests"
-        include = re.compile(r"\.pyi?$")
-        exclude = re.compile(r"")
-        report = black.Report()
-        gitignore = PathSpec.from_lines(
-            "gitwildmatch", ["exclude/", ".definitely_exclude"]
-        )
-        sources: List[Path] = []
-        expected = [
-            Path(path / "b/dont_exclude/a.py"),
-            Path(path / "b/dont_exclude/a.pyi"),
-        ]
-        this_abs = THIS_DIR.resolve()
-        sources.extend(
-            black.gen_python_files(
-                path.iterdir(),
-                this_abs,
-                include,
-                exclude,
-                None,
-                None,
-                report,
-                gitignore,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    def test_nested_gitignore(self) -> None:
-        path = Path(THIS_DIR / "data" / "nested_gitignore_tests")
-        include = re.compile(r"\.pyi?$")
-        exclude = re.compile(r"")
-        root_gitignore = black.files.get_gitignore(path)
-        report = black.Report()
-        expected: List[Path] = [
-            Path(path / "x.py"),
-            Path(path / "root/b.py"),
-            Path(path / "root/c.py"),
-            Path(path / "root/child/c.py"),
-        ]
-        this_abs = THIS_DIR.resolve()
-        sources = list(
-            black.gen_python_files(
-                path.iterdir(),
-                this_abs,
-                include,
-                exclude,
-                None,
-                None,
-                report,
-                root_gitignore,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    def test_empty_include(self) -> None:
-        path = THIS_DIR / "data" / "include_exclude_tests"
-        report = black.Report()
-        gitignore = PathSpec.from_lines("gitwildmatch", [])
-        empty = re.compile(r"")
-        sources: List[Path] = []
-        expected = [
-            Path(path / "b/exclude/a.pie"),
-            Path(path / "b/exclude/a.py"),
-            Path(path / "b/exclude/a.pyi"),
-            Path(path / "b/dont_exclude/a.pie"),
-            Path(path / "b/dont_exclude/a.py"),
-            Path(path / "b/dont_exclude/a.pyi"),
-            Path(path / "b/.definitely_exclude/a.pie"),
-            Path(path / "b/.definitely_exclude/a.py"),
-            Path(path / "b/.definitely_exclude/a.pyi"),
-            Path(path / ".gitignore"),
-            Path(path / "pyproject.toml"),
-        ]
-        this_abs = THIS_DIR.resolve()
-        sources.extend(
-            black.gen_python_files(
-                path.iterdir(),
-                this_abs,
-                empty,
-                re.compile(black.DEFAULT_EXCLUDES),
-                None,
-                None,
-                report,
-                gitignore,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    def test_extend_exclude(self) -> None:
-        path = THIS_DIR / "data" / "include_exclude_tests"
-        report = black.Report()
-        gitignore = PathSpec.from_lines("gitwildmatch", [])
-        sources: List[Path] = []
-        expected = [
-            Path(path / "b/exclude/a.py"),
-            Path(path / "b/dont_exclude/a.py"),
-        ]
-        this_abs = THIS_DIR.resolve()
-        sources.extend(
-            black.gen_python_files(
-                path.iterdir(),
-                this_abs,
-                re.compile(black.DEFAULT_INCLUDES),
-                re.compile(r"\.pyi$"),
-                re.compile(r"\.definitely_exclude"),
-                None,
-                report,
-                gitignore,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
     def test_invalid_cli_regex(self) -> None:
         for option in ["--include", "--exclude", "--extend-exclude", "--force-exclude"]:
             self.invokeBlack(["-", option, "**()(!!*)"], exit_code=2)
 
     def test_required_version_matches_version(self) -> None:
         self.invokeBlack(
-            ["--required-version", black.__version__], exit_code=0, ignore_config=True
+            ["--required-version", black.__version__, "-c", "0"],
+            exit_code=0,
+            ignore_config=True,
         )
 
-    def test_required_version_does_not_match_version(self) -> None:
+    def test_required_version_matches_partial_version(self) -> None:
+        self.invokeBlack(
+            ["--required-version", black.__version__.split(".")[0], "-c", "0"],
+            exit_code=0,
+            ignore_config=True,
+        )
+
+    def test_required_version_does_not_match_on_minor_version(self) -> None:
         self.invokeBlack(
-            ["--required-version", "20.99b"], exit_code=1, ignore_config=True
+            ["--required-version", black.__version__.split(".")[0] + ".999", "-c", "0"],
+            exit_code=1,
+            ignore_config=True,
+        )
+
+    def test_required_version_does_not_match_version(self) -> None:
+        result = BlackRunner().invoke(
+            black.main,
+            ["--required-version", "20.99b", "-c", "0"],
         )
+        self.assertEqual(result.exit_code, 1)
+        self.assertIn("required version", result.stderr)
 
     def test_preserves_line_endings(self) -> None:
         with TemporaryDirectory() as workspace:
@@ -1841,95 +1434,29 @@ class BlackTestCase(BlackBaseTestCase):
             contents = nl.join(["def f(  ):", "    pass"])
             runner = BlackRunner()
             result = runner.invoke(
-                black.main, ["-", "--fast"], input=BytesIO(contents.encode("utf8"))
+                black.main, ["-", "--fast"], input=BytesIO(contents.encode("utf-8"))
             )
             self.assertEqual(result.exit_code, 0)
             output = result.stdout_bytes
-            self.assertIn(nl.encode("utf8"), output)
+            self.assertIn(nl.encode("utf-8"), output)
             if nl == "\n":
                 self.assertNotIn(b"\r\n", output)
 
+    def test_normalize_line_endings(self) -> None:
+        with TemporaryDirectory() as workspace:
+            test_file = Path(workspace) / "test.py"
+            for data, expected in (
+                (b"c\r\nc\n ", b"c\r\nc\r\n"),
+                (b"l\nl\r\n ", b"l\nl\n"),
+            ):
+                test_file.write_bytes(data)
+                ff(test_file, write_back=black.WriteBack.YES)
+                self.assertEqual(test_file.read_bytes(), expected)
+
     def test_assert_equivalent_different_asts(self) -> None:
         with self.assertRaises(AssertionError):
             black.assert_equivalent("{}", "None")
 
-    def test_symlink_out_of_root_directory(self) -> None:
-        path = MagicMock()
-        root = THIS_DIR.resolve()
-        child = MagicMock()
-        include = re.compile(black.DEFAULT_INCLUDES)
-        exclude = re.compile(black.DEFAULT_EXCLUDES)
-        report = black.Report()
-        gitignore = PathSpec.from_lines("gitwildmatch", [])
-        # `child` should behave like a symlink which resolved path is clearly
-        # outside of the `root` directory.
-        path.iterdir.return_value = [child]
-        child.resolve.return_value = Path("/a/b/c")
-        child.as_posix.return_value = "/a/b/c"
-        child.is_symlink.return_value = True
-        try:
-            list(
-                black.gen_python_files(
-                    path.iterdir(),
-                    root,
-                    include,
-                    exclude,
-                    None,
-                    None,
-                    report,
-                    gitignore,
-                )
-            )
-        except ValueError as ve:
-            self.fail(f"`get_python_files_in_dir()` failed: {ve}")
-        path.iterdir.assert_called_once()
-        child.resolve.assert_called_once()
-        child.is_symlink.assert_called_once()
-        # `child` should behave like a strange file which resolved path is clearly
-        # outside of the `root` directory.
-        child.is_symlink.return_value = False
-        with self.assertRaises(ValueError):
-            list(
-                black.gen_python_files(
-                    path.iterdir(),
-                    root,
-                    include,
-                    exclude,
-                    None,
-                    None,
-                    report,
-                    gitignore,
-                )
-            )
-        path.iterdir.assert_called()
-        self.assertEqual(path.iterdir.call_count, 2)
-        child.resolve.assert_called()
-        self.assertEqual(child.resolve.call_count, 2)
-        child.is_symlink.assert_called()
-        self.assertEqual(child.is_symlink.call_count, 2)
-
-    def test_shhh_click(self) -> None:
-        try:
-            from click import _unicodefun
-        except ModuleNotFoundError:
-            self.skipTest("Incompatible Click version")
-        if not hasattr(_unicodefun, "_verify_python3_env"):
-            self.skipTest("Incompatible Click version")
-        # First, let's see if Click is crashing with a preferred ASCII charset.
-        with patch("locale.getpreferredencoding") as gpe:
-            gpe.return_value = "ASCII"
-            with self.assertRaises(RuntimeError):
-                _unicodefun._verify_python3_env()  # type: ignore
-        # Now, let's silence Click...
-        black.patch_click()
-        # ...and confirm it's silent.
-        with patch("locale.getpreferredencoding") as gpe:
-            gpe.return_value = "ASCII"
-            try:
-                _unicodefun._verify_python3_env()  # type: ignore
-            except RuntimeError as re:
-                self.fail(f"`patch_click()` failed, exception still raised: {re}")
-
     def test_root_logger_not_used_directly(self) -> None:
         def fail(*args: Any, **kwargs: Any) -> None:
             self.fail("Record created with root logger")
@@ -1964,9 +1491,89 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertEqual(config["color"], True)
         self.assertEqual(config["line_length"], 79)
         self.assertEqual(config["target_version"], ["py36", "py37", "py38"])
+        self.assertEqual(config["python_cell_magics"], ["custom1", "custom2"])
         self.assertEqual(config["exclude"], r"\.pyi?$")
         self.assertEqual(config["include"], r"\.py?$")
 
+    def test_parse_pyproject_toml_project_metadata(self) -> None:
+        for test_toml, expected in [
+            ("only_black_pyproject.toml", ["py310"]),
+            ("only_metadata_pyproject.toml", ["py37", "py38", "py39", "py310"]),
+            ("neither_pyproject.toml", None),
+            ("both_pyproject.toml", ["py310"]),
+        ]:
+            test_toml_file = THIS_DIR / "data" / "project_metadata" / test_toml
+            config = black.parse_pyproject_toml(str(test_toml_file))
+            self.assertEqual(config.get("target_version"), expected)
+
+    def test_infer_target_version(self) -> None:
+        for version, expected in [
+            ("3.6", [TargetVersion.PY36]),
+            ("3.11.0rc1", [TargetVersion.PY311]),
+            (">=3.10", [TargetVersion.PY310, TargetVersion.PY311, TargetVersion.PY312]),
+            (
+                ">=3.10.6",
+                [TargetVersion.PY310, TargetVersion.PY311, TargetVersion.PY312],
+            ),
+            ("<3.6", [TargetVersion.PY33, TargetVersion.PY34, TargetVersion.PY35]),
+            (">3.7,<3.10", [TargetVersion.PY38, TargetVersion.PY39]),
+            (
+                ">3.7,!=3.8,!=3.9",
+                [TargetVersion.PY310, TargetVersion.PY311, TargetVersion.PY312],
+            ),
+            (
+                "> 3.9.4, != 3.10.3",
+                [
+                    TargetVersion.PY39,
+                    TargetVersion.PY310,
+                    TargetVersion.PY311,
+                    TargetVersion.PY312,
+                ],
+            ),
+            (
+                "!=3.3,!=3.4",
+                [
+                    TargetVersion.PY35,
+                    TargetVersion.PY36,
+                    TargetVersion.PY37,
+                    TargetVersion.PY38,
+                    TargetVersion.PY39,
+                    TargetVersion.PY310,
+                    TargetVersion.PY311,
+                    TargetVersion.PY312,
+                ],
+            ),
+            (
+                "==3.*",
+                [
+                    TargetVersion.PY33,
+                    TargetVersion.PY34,
+                    TargetVersion.PY35,
+                    TargetVersion.PY36,
+                    TargetVersion.PY37,
+                    TargetVersion.PY38,
+                    TargetVersion.PY39,
+                    TargetVersion.PY310,
+                    TargetVersion.PY311,
+                    TargetVersion.PY312,
+                ],
+            ),
+            ("==3.8.*", [TargetVersion.PY38]),
+            (None, None),
+            ("", None),
+            ("invalid", None),
+            ("==invalid", None),
+            (">3.9,!=invalid", None),
+            ("3", None),
+            ("3.2", None),
+            ("2.7.18", None),
+            ("==2.7", None),
+            (">3.10,<3.11", None),
+        ]:
+            test_toml = {"project": {"requires-python": version}}
+            result = black.files.infer_target_version(test_toml)
+            self.assertEqual(result, expected)
+
     def test_read_pyproject_toml(self) -> None:
         test_toml_file = THIS_DIR / "test.toml"
         fake_ctx = FakeContext()
@@ -1981,6 +1588,40 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertEqual(config["exclude"], r"\.pyi?$")
         self.assertEqual(config["include"], r"\.py?$")
 
+    def test_read_pyproject_toml_from_stdin(self) -> None:
+        with TemporaryDirectory() as workspace:
+            root = Path(workspace)
+
+            src_dir = root / "src"
+            src_dir.mkdir()
+
+            src_pyproject = src_dir / "pyproject.toml"
+            src_pyproject.touch()
+
+            test_toml_content = (THIS_DIR / "test.toml").read_text(encoding="utf-8")
+            src_pyproject.write_text(test_toml_content, encoding="utf-8")
+
+            src_python = src_dir / "foo.py"
+            src_python.touch()
+
+            fake_ctx = FakeContext()
+            fake_ctx.params["src"] = ("-",)
+            fake_ctx.params["stdin_filename"] = str(src_python)
+
+            with change_directory(root):
+                black.read_pyproject_toml(fake_ctx, FakeParameter(), None)
+
+            config = fake_ctx.default_map
+            self.assertEqual(config["verbose"], "1")
+            self.assertEqual(config["check"], "no")
+            self.assertEqual(config["diff"], "y")
+            self.assertEqual(config["color"], "True")
+            self.assertEqual(config["line_length"], "79")
+            self.assertEqual(config["target_version"], ["py36", "py37", "py38"])
+            self.assertEqual(config["exclude"], r"\.pyi?$")
+            self.assertEqual(config["include"], r"\.py?$")
+
+    @pytest.mark.incompatible_with_mypyc
     def test_find_project_root(self) -> None:
         with TemporaryDirectory() as workspace:
             root = Path(workspace)
@@ -1998,10 +1639,38 @@ class BlackTestCase(BlackBaseTestCase):
             src_python.touch()
 
             self.assertEqual(
-                black.find_project_root((src_dir, test_dir)), root.resolve()
+                black.find_project_root((src_dir, test_dir)),
+                (root.resolve(), "pyproject.toml"),
+            )
+            self.assertEqual(
+                black.find_project_root((src_dir,)),
+                (src_dir.resolve(), "pyproject.toml"),
+            )
+            self.assertEqual(
+                black.find_project_root((src_python,)),
+                (src_dir.resolve(), "pyproject.toml"),
+            )
+
+            with change_directory(test_dir):
+                self.assertEqual(
+                    black.find_project_root(("-",), stdin_filename="../src/a.py"),
+                    (src_dir.resolve(), "pyproject.toml"),
+                )
+
+    @patch(
+        "black.files.find_user_pyproject_toml",
+    )
+    def test_find_pyproject_toml(self, find_user_pyproject_toml: MagicMock) -> None:
+        find_user_pyproject_toml.side_effect = RuntimeError()
+
+        with redirect_stderr(io.StringIO()) as stderr:
+            result = black.files.find_pyproject_toml(
+                path_search_start=(str(Path.cwd().root),)
             )
-            self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
-            self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
+
+        assert result is None
+        err = stderr.getvalue()
+        assert "Ignoring user configuration" in err
 
     @patch(
         "black.files.find_user_pyproject_toml",
@@ -2041,17 +1710,31 @@ class BlackTestCase(BlackBaseTestCase):
             return
 
         # https://bugs.python.org/issue33660
-
-        old_cwd = Path.cwd()
-        try:
-            root = Path("/")
-            os.chdir(str(root))
+        root = Path("/")
+        with change_directory(root):
             path = Path("workspace") / "project"
             report = black.Report(verbose=True)
             normalized_path = black.normalize_path_maybe_ignore(path, root, report)
             self.assertEqual(normalized_path, "workspace/project")
-        finally:
-            os.chdir(str(old_cwd))
+
+    def test_normalize_path_ignore_windows_junctions_outside_of_root(self) -> None:
+        if system() != "Windows":
+            return
+
+        with TemporaryDirectory() as workspace:
+            root = Path(workspace)
+            junction_dir = root / "junction"
+            junction_target_outside_of_root = root / ".."
+            os.system(f"mklink /J {junction_dir} {junction_target_outside_of_root}")
+
+            report = black.Report(verbose=True)
+            normalized_path = black.normalize_path_maybe_ignore(
+                junction_dir, root, report
+            )
+            # Manually delete for Python < 3.8
+            os.system(f"rmdir {junction_dir}")
+
+            self.assertEqual(normalized_path, None)
 
     def test_newline_comment_interaction(self) -> None:
         source = "class A:\\\r\n# type: ignore\n pass\n"
@@ -2059,17 +1742,16 @@ class BlackTestCase(BlackBaseTestCase):
         black.assert_stable(source, output, mode=DEFAULT_MODE)
 
     def test_bpo_2142_workaround(self) -> None:
-
         # https://bugs.python.org/issue2142
 
-        source, _ = read_data("missing_final_newline.py")
+        source, _ = read_data("miscellaneous", "missing_final_newline")
         # read_data adds a trailing newline
         source = source.rstrip()
-        expected, _ = read_data("missing_final_newline.diff")
+        expected, _ = read_data("miscellaneous", "missing_final_newline.diff")
         tmp_file = Path(black.dump_to_file(source, ensure_final_newline=False))
         diff_header = re.compile(
             rf"{re.escape(str(tmp_file))}\t\d\d\d\d-\d\d-\d\d "
-            r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
+            r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d\+\d\d:\d\d"
         )
         try:
             result = BlackRunner().invoke(black.main, ["--diff", str(tmp_file)])
@@ -2080,27 +1762,6 @@ class BlackTestCase(BlackBaseTestCase):
         actual = diff_header.sub(DETERMINISTIC_HEADER, actual)
         self.assertEqual(actual, expected)
 
-    @pytest.mark.python2
-    def test_docstring_reformat_for_py27(self) -> None:
-        """
-        Check that stripping trailing whitespace from Python 2 docstrings
-        doesn't trigger a "not equivalent to source" error
-        """
-        source = (
-            b'def foo():\r\n    """Testing\r\n    Testing """\r\n    print "Foo"\r\n'
-        )
-        expected = 'def foo():\n    """Testing\n    Testing"""\n    print "Foo"\n'
-
-        result = CliRunner().invoke(
-            black.main,
-            ["-", "-q", "--target-version=py27"],
-            input=BytesIO(source),
-        )
-
-        self.assertEqual(result.exit_code, 0)
-        actual = result.output
-        self.assertFormatEqual(actual, expected)
-
     @staticmethod
     def compare_results(
         result: click.testing.Result, expected_value: str, expected_exit_code: int
@@ -2173,6 +1834,7 @@ class BlackTestCase(BlackBaseTestCase):
         assert output == result_diff, "The output did not match the expected value."
         assert result.exit_code == 0, "The exit code is incorrect."
 
+    @pytest.mark.incompatible_with_mypyc
     def test_code_option_safe(self) -> None:
         """Test that the code option throws an error when the sanity checks fail."""
         # Patch black.assert_equivalent to ensure the sanity checks fail
@@ -2197,19 +1859,18 @@ class BlackTestCase(BlackBaseTestCase):
 
             self.compare_results(result, formatted, 0)
 
+    @pytest.mark.incompatible_with_mypyc
     def test_code_option_config(self) -> None:
         """
         Test that the code option finds the pyproject.toml in the current directory.
         """
         with patch.object(black, "parse_pyproject_toml", return_value={}) as parse:
-            # Make sure we are in the project root with the pyproject file
-            if not Path("tests").exists():
-                os.chdir("..")
-
             args = ["--code", "print"]
-            CliRunner().invoke(black.main, args)
+            # This is the only directory known to contain a pyproject.toml
+            with change_directory(PROJECT_ROOT):
+                CliRunner().invoke(black.main, args)
+                pyproject_path = Path(Path.cwd(), "pyproject.toml").resolve()
 
-            pyproject_path = Path(Path().cwd(), "pyproject.toml").resolve()
             assert (
                 len(parse.mock_calls) >= 1
             ), "Expected config parse to be called with the current directory."
@@ -2219,34 +1880,570 @@ class BlackTestCase(BlackBaseTestCase):
                 call_args[0].lower() == str(pyproject_path).lower()
             ), "Incorrect config loaded."
 
+    @pytest.mark.incompatible_with_mypyc
     def test_code_option_parent_config(self) -> None:
         """
         Test that the code option finds the pyproject.toml in the parent directory.
         """
         with patch.object(black, "parse_pyproject_toml", return_value={}) as parse:
-            # Make sure we are in the tests directory
-            if Path("tests").exists():
-                os.chdir("tests")
+            with change_directory(THIS_DIR):
+                args = ["--code", "print"]
+                CliRunner().invoke(black.main, args)
 
-            args = ["--code", "print"]
-            CliRunner().invoke(black.main, args)
+                pyproject_path = Path(Path().cwd().parent, "pyproject.toml").resolve()
+                assert (
+                    len(parse.mock_calls) >= 1
+                ), "Expected config parse to be called with the current directory."
 
-            pyproject_path = Path(Path().cwd().parent, "pyproject.toml").resolve()
-            assert (
-                len(parse.mock_calls) >= 1
-            ), "Expected config parse to be called with the current directory."
+                _, call_args, _ = parse.mock_calls[0]
+                assert (
+                    call_args[0].lower() == str(pyproject_path).lower()
+                ), "Incorrect config loaded."
 
-            _, call_args, _ = parse.mock_calls[0]
-            assert (
-                call_args[0].lower() == str(pyproject_path).lower()
-            ), "Incorrect config loaded."
+    def test_for_handled_unexpected_eof_error(self) -> None:
+        """
+        Test that an unexpected EOF SyntaxError is nicely presented.
+        """
+        with pytest.raises(black.parsing.InvalidInput) as exc_info:
+            black.lib2to3_parse("print(", {})
+
+        exc_info.match("Cannot parse: 2:0: EOF in multi-line statement")
+
+    def test_equivalency_ast_parse_failure_includes_error(self) -> None:
+        with pytest.raises(AssertionError) as err:
+            black.assert_equivalent("a«»a  = 1", "a«»a  = 1")
+
+        err.match("--safe")
+        # Unfortunately the SyntaxError message has changed in newer versions so we
+        # can't match it directly.
+        err.match("invalid character")
+        err.match(r"\(<unknown>, line 1\)")
+
+
+class TestCaching:
+    def test_get_cache_dir(
+        self,
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        # Create multiple cache directories
+        workspace1 = tmp_path / "ws1"
+        workspace1.mkdir()
+        workspace2 = tmp_path / "ws2"
+        workspace2.mkdir()
+
+        # Force user_cache_dir to use the temporary directory for easier assertions
+        patch_user_cache_dir = patch(
+            target="black.cache.user_cache_dir",
+            autospec=True,
+            return_value=str(workspace1),
+        )
+
+        # If BLACK_CACHE_DIR is not set, use user_cache_dir
+        monkeypatch.delenv("BLACK_CACHE_DIR", raising=False)
+        with patch_user_cache_dir:
+            assert get_cache_dir() == workspace1
+
+        # If it is set, use the path provided in the env var.
+        monkeypatch.setenv("BLACK_CACHE_DIR", str(workspace2))
+        assert get_cache_dir() == workspace2
+
+    def test_cache_broken_file(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir() as workspace:
+            cache_file = get_cache_file(mode)
+            cache_file.write_text("this is not a pickle", encoding="utf-8")
+            assert black.read_cache(mode) == {}
+            src = (workspace / "test.py").resolve()
+            src.write_text("print('hello')", encoding="utf-8")
+            invokeBlack([str(src)])
+            cache = black.read_cache(mode)
+            assert str(src) in cache
+
+    def test_cache_single_file_already_cached(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir() as workspace:
+            src = (workspace / "test.py").resolve()
+            src.write_text("print('hello')", encoding="utf-8")
+            black.write_cache({}, [src], mode)
+            invokeBlack([str(src)])
+            assert src.read_text(encoding="utf-8") == "print('hello')"
+
+    @event_loop()
+    def test_cache_multiple_files(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir() as workspace, patch(
+            "concurrent.futures.ProcessPoolExecutor", new=ThreadPoolExecutor
+        ):
+            one = (workspace / "one.py").resolve()
+            one.write_text("print('hello')", encoding="utf-8")
+            two = (workspace / "two.py").resolve()
+            two.write_text("print('hello')", encoding="utf-8")
+            black.write_cache({}, [one], mode)
+            invokeBlack([str(workspace)])
+            assert one.read_text(encoding="utf-8") == "print('hello')"
+            assert two.read_text(encoding="utf-8") == 'print("hello")\n'
+            cache = black.read_cache(mode)
+            assert str(one) in cache
+            assert str(two) in cache
+
+    @pytest.mark.parametrize("color", [False, True], ids=["no-color", "with-color"])
+    def test_no_cache_when_writeback_diff(self, color: bool) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir() as workspace:
+            src = (workspace / "test.py").resolve()
+            src.write_text("print('hello')", encoding="utf-8")
+            with patch("black.read_cache") as read_cache, patch(
+                "black.write_cache"
+            ) as write_cache:
+                cmd = [str(src), "--diff"]
+                if color:
+                    cmd.append("--color")
+                invokeBlack(cmd)
+                cache_file = get_cache_file(mode)
+                assert cache_file.exists() is False
+                write_cache.assert_not_called()
+                read_cache.assert_not_called()
+
+    @pytest.mark.parametrize("color", [False, True], ids=["no-color", "with-color"])
+    @event_loop()
+    def test_output_locking_when_writeback_diff(self, color: bool) -> None:
+        with cache_dir() as workspace:
+            for tag in range(0, 4):
+                src = (workspace / f"test{tag}.py").resolve()
+                src.write_text("print('hello')", encoding="utf-8")
+            with patch(
+                "black.concurrency.Manager", wraps=multiprocessing.Manager
+            ) as mgr:
+                cmd = ["--diff", str(workspace)]
+                if color:
+                    cmd.append("--color")
+                invokeBlack(cmd, exit_code=0)
+                # this isn't quite doing what we want, but if it _isn't_
+                # called then we cannot be using the lock it provides
+                mgr.assert_called()
+
+    def test_no_cache_when_stdin(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir():
+            result = CliRunner().invoke(
+                black.main, ["-"], input=BytesIO(b"print('hello')")
+            )
+            assert not result.exit_code
+            cache_file = get_cache_file(mode)
+            assert not cache_file.exists()
+
+    def test_read_cache_no_cachefile(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir():
+            assert black.read_cache(mode) == {}
+
+    def test_write_cache_read_cache(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir() as workspace:
+            src = (workspace / "test.py").resolve()
+            src.touch()
+            black.write_cache({}, [src], mode)
+            cache = black.read_cache(mode)
+            assert str(src) in cache
+            assert cache[str(src)] == black.get_cache_info(src)
+
+    def test_filter_cached(self) -> None:
+        with TemporaryDirectory() as workspace:
+            path = Path(workspace)
+            uncached = (path / "uncached").resolve()
+            cached = (path / "cached").resolve()
+            cached_but_changed = (path / "changed").resolve()
+            uncached.touch()
+            cached.touch()
+            cached_but_changed.touch()
+            cache = {
+                str(cached): black.get_cache_info(cached),
+                str(cached_but_changed): (0.0, 0),
+            }
+            todo, done = black.cache.filter_cached(
+                cache, {uncached, cached, cached_but_changed}
+            )
+            assert todo == {uncached, cached_but_changed}
+            assert done == {cached}
+
+    def test_write_cache_creates_directory_if_needed(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir(exists=False) as workspace:
+            assert not workspace.exists()
+            black.write_cache({}, [], mode)
+            assert workspace.exists()
+
+    @event_loop()
+    def test_failed_formatting_does_not_get_cached(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir() as workspace, patch(
+            "concurrent.futures.ProcessPoolExecutor", new=ThreadPoolExecutor
+        ):
+            failing = (workspace / "failing.py").resolve()
+            failing.write_text("not actually python", encoding="utf-8")
+            clean = (workspace / "clean.py").resolve()
+            clean.write_text('print("hello")\n', encoding="utf-8")
+            invokeBlack([str(workspace)], exit_code=123)
+            cache = black.read_cache(mode)
+            assert str(failing) not in cache
+            assert str(clean) in cache
+
+    def test_write_cache_write_fail(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir(), patch.object(Path, "open") as mock:
+            mock.side_effect = OSError
+            black.write_cache({}, [], mode)
+
+    def test_read_cache_line_lengths(self) -> None:
+        mode = DEFAULT_MODE
+        short_mode = replace(DEFAULT_MODE, line_length=1)
+        with cache_dir() as workspace:
+            path = (workspace / "file.py").resolve()
+            path.touch()
+            black.write_cache({}, [path], mode)
+            one = black.read_cache(mode)
+            assert str(path) in one
+            two = black.read_cache(short_mode)
+            assert str(path) not in two
+
+
+def assert_collected_sources(
+    src: Sequence[Union[str, Path]],
+    expected: Sequence[Union[str, Path]],
+    *,
+    ctx: Optional[FakeContext] = None,
+    exclude: Optional[str] = None,
+    include: Optional[str] = None,
+    extend_exclude: Optional[str] = None,
+    force_exclude: Optional[str] = None,
+    stdin_filename: Optional[str] = None,
+) -> None:
+    gs_src = tuple(str(Path(s)) for s in src)
+    gs_expected = [Path(s) for s in expected]
+    gs_exclude = None if exclude is None else compile_pattern(exclude)
+    gs_include = DEFAULT_INCLUDE if include is None else compile_pattern(include)
+    gs_extend_exclude = (
+        None if extend_exclude is None else compile_pattern(extend_exclude)
+    )
+    gs_force_exclude = None if force_exclude is None else compile_pattern(force_exclude)
+    collected = black.get_sources(
+        ctx=ctx or FakeContext(),
+        src=gs_src,
+        quiet=False,
+        verbose=False,
+        include=gs_include,
+        exclude=gs_exclude,
+        extend_exclude=gs_extend_exclude,
+        force_exclude=gs_force_exclude,
+        report=black.Report(),
+        stdin_filename=stdin_filename,
+    )
+    assert sorted(collected) == sorted(gs_expected)
+
+
+class TestFileCollection:
+    def test_include_exclude(self) -> None:
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        src = [path]
+        expected = [
+            Path(path / "b/dont_exclude/a.py"),
+            Path(path / "b/dont_exclude/a.pyi"),
+        ]
+        assert_collected_sources(
+            src,
+            expected,
+            include=r"\.pyi?$",
+            exclude=r"/exclude/|/\.definitely_exclude/",
+        )
+
+    def test_gitignore_used_as_default(self) -> None:
+        base = Path(DATA_DIR / "include_exclude_tests")
+        expected = [
+            base / "b/.definitely_exclude/a.py",
+            base / "b/.definitely_exclude/a.pyi",
+        ]
+        src = [base / "b/"]
+        ctx = FakeContext()
+        ctx.obj["root"] = base
+        assert_collected_sources(src, expected, ctx=ctx, extend_exclude=r"/exclude/")
+
+    def test_gitignore_used_on_multiple_sources(self) -> None:
+        root = Path(DATA_DIR / "gitignore_used_on_multiple_sources")
+        expected = [
+            root / "dir1" / "b.py",
+            root / "dir2" / "b.py",
+        ]
+        ctx = FakeContext()
+        ctx.obj["root"] = root
+        src = [root / "dir1", root / "dir2"]
+        assert_collected_sources(src, expected, ctx=ctx)
+
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
+    def test_exclude_for_issue_1572(self) -> None:
+        # Exclude shouldn't touch files that were explicitly given to Black through the
+        # CLI. Exclude is supposed to only apply to the recursive discovery of files.
+        # https://github.com/psf/black/issues/1572
+        path = DATA_DIR / "include_exclude_tests"
+        src = [path / "b/exclude/a.py"]
+        expected = [path / "b/exclude/a.py"]
+        assert_collected_sources(src, expected, include="", exclude=r"/exclude/|a\.py")
+
+    def test_gitignore_exclude(self) -> None:
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        include = re.compile(r"\.pyi?$")
+        exclude = re.compile(r"")
+        report = black.Report()
+        gitignore = PathSpec.from_lines(
+            "gitwildmatch", ["exclude/", ".definitely_exclude"]
+        )
+        sources: List[Path] = []
+        expected = [
+            Path(path / "b/dont_exclude/a.py"),
+            Path(path / "b/dont_exclude/a.pyi"),
+        ]
+        this_abs = THIS_DIR.resolve()
+        sources.extend(
+            black.gen_python_files(
+                path.iterdir(),
+                this_abs,
+                include,
+                exclude,
+                None,
+                None,
+                report,
+                {path: gitignore},
+                verbose=False,
+                quiet=False,
+            )
+        )
+        assert sorted(expected) == sorted(sources)
+
+    def test_nested_gitignore(self) -> None:
+        path = Path(THIS_DIR / "data" / "nested_gitignore_tests")
+        include = re.compile(r"\.pyi?$")
+        exclude = re.compile(r"")
+        root_gitignore = black.files.get_gitignore(path)
+        report = black.Report()
+        expected: List[Path] = [
+            Path(path / "x.py"),
+            Path(path / "root/b.py"),
+            Path(path / "root/c.py"),
+            Path(path / "root/child/c.py"),
+        ]
+        this_abs = THIS_DIR.resolve()
+        sources = list(
+            black.gen_python_files(
+                path.iterdir(),
+                this_abs,
+                include,
+                exclude,
+                None,
+                None,
+                report,
+                {path: root_gitignore},
+                verbose=False,
+                quiet=False,
+            )
+        )
+        assert sorted(expected) == sorted(sources)
+
+    def test_nested_gitignore_directly_in_source_directory(self) -> None:
+        # https://github.com/psf/black/issues/2598
+        path = Path(DATA_DIR / "nested_gitignore_tests")
+        src = Path(path / "root" / "child")
+        expected = [src / "a.py", src / "c.py"]
+        assert_collected_sources([src], expected)
+
+    def test_invalid_gitignore(self) -> None:
+        path = THIS_DIR / "data" / "invalid_gitignore_tests"
+        empty_config = path / "pyproject.toml"
+        result = BlackRunner().invoke(
+            black.main, ["--verbose", "--config", str(empty_config), str(path)]
+        )
+        assert result.exit_code == 1
+        assert result.stderr_bytes is not None
+
+        gitignore = path / ".gitignore"
+        assert f"Could not parse {gitignore}" in result.stderr_bytes.decode()
+
+    def test_invalid_nested_gitignore(self) -> None:
+        path = THIS_DIR / "data" / "invalid_nested_gitignore_tests"
+        empty_config = path / "pyproject.toml"
+        result = BlackRunner().invoke(
+            black.main, ["--verbose", "--config", str(empty_config), str(path)]
+        )
+        assert result.exit_code == 1
+        assert result.stderr_bytes is not None
+
+        gitignore = path / "a" / ".gitignore"
+        assert f"Could not parse {gitignore}" in result.stderr_bytes.decode()
+
+    def test_gitignore_that_ignores_subfolders(self) -> None:
+        # If gitignore with */* is in root
+        root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests" / "subdir")
+        expected = [root / "b.py"]
+        ctx = FakeContext()
+        ctx.obj["root"] = root
+        assert_collected_sources([root], expected, ctx=ctx)
+
+        # If .gitignore with */* is nested
+        root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests")
+        expected = [
+            root / "a.py",
+            root / "subdir" / "b.py",
+        ]
+        ctx = FakeContext()
+        ctx.obj["root"] = root
+        assert_collected_sources([root], expected, ctx=ctx)
+
+        # If command is executed from outer dir
+        root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests")
+        target = root / "subdir"
+        expected = [target / "b.py"]
+        ctx = FakeContext()
+        ctx.obj["root"] = root
+        assert_collected_sources([target], expected, ctx=ctx)
+
+    def test_empty_include(self) -> None:
+        path = DATA_DIR / "include_exclude_tests"
+        src = [path]
+        expected = [
+            Path(path / "b/exclude/a.pie"),
+            Path(path / "b/exclude/a.py"),
+            Path(path / "b/exclude/a.pyi"),
+            Path(path / "b/dont_exclude/a.pie"),
+            Path(path / "b/dont_exclude/a.py"),
+            Path(path / "b/dont_exclude/a.pyi"),
+            Path(path / "b/.definitely_exclude/a.pie"),
+            Path(path / "b/.definitely_exclude/a.py"),
+            Path(path / "b/.definitely_exclude/a.pyi"),
+            Path(path / ".gitignore"),
+            Path(path / "pyproject.toml"),
+        ]
+        # Setting exclude explicitly to an empty string to block .gitignore usage.
+        assert_collected_sources(src, expected, include="", exclude="")
+
+    def test_extend_exclude(self) -> None:
+        path = DATA_DIR / "include_exclude_tests"
+        src = [path]
+        expected = [
+            Path(path / "b/exclude/a.py"),
+            Path(path / "b/dont_exclude/a.py"),
+        ]
+        assert_collected_sources(
+            src, expected, exclude=r"\.pyi$", extend_exclude=r"\.definitely_exclude"
+        )
+
+    @pytest.mark.incompatible_with_mypyc
+    def test_symlink_out_of_root_directory(self) -> None:
+        path = MagicMock()
+        root = THIS_DIR.resolve()
+        child = MagicMock()
+        include = re.compile(black.DEFAULT_INCLUDES)
+        exclude = re.compile(black.DEFAULT_EXCLUDES)
+        report = black.Report()
+        gitignore = PathSpec.from_lines("gitwildmatch", [])
+        # `child` should behave like a symlink which resolved path is clearly
+        # outside of the `root` directory.
+        path.iterdir.return_value = [child]
+        child.resolve.return_value = Path("/a/b/c")
+        child.as_posix.return_value = "/a/b/c"
+        try:
+            list(
+                black.gen_python_files(
+                    path.iterdir(),
+                    root,
+                    include,
+                    exclude,
+                    None,
+                    None,
+                    report,
+                    {path: gitignore},
+                    verbose=False,
+                    quiet=False,
+                )
+            )
+        except ValueError as ve:
+            pytest.fail(f"`get_python_files_in_dir()` failed: {ve}")
+        path.iterdir.assert_called_once()
+        child.resolve.assert_called_once()
+
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
+    def test_get_sources_with_stdin(self) -> None:
+        src = ["-"]
+        expected = ["-"]
+        assert_collected_sources(src, expected, include="", exclude=r"/exclude/|a\.py")
+
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
+    def test_get_sources_with_stdin_filename(self) -> None:
+        src = ["-"]
+        stdin_filename = str(THIS_DIR / "data/collections.py")
+        expected = [f"__BLACK_STDIN_FILENAME__{stdin_filename}"]
+        assert_collected_sources(
+            src,
+            expected,
+            exclude=r"/exclude/a\.py",
+            stdin_filename=stdin_filename,
+        )
+
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
+    def test_get_sources_with_stdin_filename_and_exclude(self) -> None:
+        # Exclude shouldn't exclude stdin_filename since it is mimicking the
+        # file being passed directly. This is the same as
+        # test_exclude_for_issue_1572
+        path = DATA_DIR / "include_exclude_tests"
+        src = ["-"]
+        stdin_filename = str(path / "b/exclude/a.py")
+        expected = [f"__BLACK_STDIN_FILENAME__{stdin_filename}"]
+        assert_collected_sources(
+            src,
+            expected,
+            exclude=r"/exclude/|a\.py",
+            stdin_filename=stdin_filename,
+        )
+
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
+    def test_get_sources_with_stdin_filename_and_extend_exclude(self) -> None:
+        # Extend exclude shouldn't exclude stdin_filename since it is mimicking the
+        # file being passed directly. This is the same as
+        # test_exclude_for_issue_1572
+        src = ["-"]
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        stdin_filename = str(path / "b/exclude/a.py")
+        expected = [f"__BLACK_STDIN_FILENAME__{stdin_filename}"]
+        assert_collected_sources(
+            src,
+            expected,
+            extend_exclude=r"/exclude/|a\.py",
+            stdin_filename=stdin_filename,
+        )
+
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
+    def test_get_sources_with_stdin_filename_and_force_exclude(self) -> None:
+        # Force exclude should exclude the file when passing it through
+        # stdin_filename
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        stdin_filename = str(path / "b/exclude/a.py")
+        assert_collected_sources(
+            src=["-"],
+            expected=[],
+            force_exclude=r"/exclude/|a\.py",
+            stdin_filename=stdin_filename,
+        )
 
 
-with open(black.__file__, "r", encoding="utf-8") as _bf:
-    black_source_lines = _bf.readlines()
+try:
+    with open(black.__file__, "r", encoding="utf-8") as _bf:
+        black_source_lines = _bf.readlines()
+except UnicodeDecodeError:
+    if not black.COMPILED:
+        raise
 
 
-def tracefunc(frame: types.FrameType, event: str, arg: Any) -> Callable:
+def tracefunc(
+    frame: types.FrameType, event: str, arg: Any
+) -> Callable[[types.FrameType, str, Any], Any]:
     """Show function calls `from black/__init__.py` as they happen.
 
     Register this with `sys.settrace()` in a test you're debugging.
@@ -2266,7 +2463,3 @@ def tracefunc(frame: types.FrameType, event: str, arg: Any) -> Callable:
     if "black/__init__.py" in filename:
         print(f"{' ' * stack}{lineno}:{funcname}")
     return tracefunc
-
-
-if __name__ == "__main__":
-    unittest.main(module="test_black")