X-Git-Url: https://git.madduck.net/etc/vim.git/blobdiff_plain/204f76e0c02a12aeccb3ab708fe41f7e95435a29..085efac037c07ef299edbf48a4d871f17b296743:/tests/test_black.py

diff --git a/tests/test_black.py b/tests/test_black.py
index 7d855ca..9259853 100644
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -1,67 +1,77 @@
 #!/usr/bin/env python3
-import multiprocessing
+
 import asyncio
+import inspect
+import io
 import logging
+import multiprocessing
+import os
+import sys
+import types
+import unittest
 from concurrent.futures import ThreadPoolExecutor
 from contextlib import contextmanager
 from dataclasses import replace
-import inspect
-from io import BytesIO, TextIOWrapper
-import os
+from io import BytesIO
 from pathlib import Path
 from platform import system
-import regex as re
-import sys
 from tempfile import TemporaryDirectory
-import types
 from typing import (
     Any,
-    BinaryIO,
     Callable,
     Dict,
-    Generator,
-    List,
     Iterator,
+    List,
+    Optional,
+    Sequence,
     TypeVar,
+    Union,
 )
-import pytest
-import unittest
-from unittest.mock import patch, MagicMock
+from unittest.mock import MagicMock, patch
 
 import click
+import pytest
+import re
 from click import unstyle
 from click.testing import CliRunner
+from pathspec import PathSpec
 
 import black
+import black.files
 from black import Feature, TargetVersion
-
-from pathspec import PathSpec
+from black import re_compile_maybe_verbose as compile_pattern
+from black.cache import get_cache_file
+from black.debug import DebugVisitor
+from black.output import color_diff, diff
+from black.report import Report
 
 # 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,
+    read_data,
 )
-from .test_primer import PrimerCLITests  # noqa: F401
-
 
 THIS_FILE = Path(__file__)
-PY36_VERSIONS = {
-    TargetVersion.PY36,
-    TargetVersion.PY37,
-    TargetVersion.PY38,
-    TargetVersion.PY39,
-}
 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\-:+\. ]+")
+
 
 @contextmanager
 def cache_dir(exists: bool = True) -> Iterator[Path]:
@@ -69,7 +79,7 @@ def cache_dir(exists: bool = True) -> Iterator[Path]:
         cache_dir = Path(workspace)
         if not exists:
             cache_dir = cache_dir / "new"
-        with patch("black.CACHE_DIR", cache_dir):
+        with patch("black.cache.CACHE_DIR", cache_dir):
             yield cache_dir
 
 
@@ -100,56 +110,32 @@ class FakeParameter(click.Parameter):
 
 
 class BlackRunner(CliRunner):
-    """Modify CliRunner so that stderr is not merged with stdout.
-
-    This is a hack that can be removed once we depend on Click 7.x"""
+    """Make sure STDOUT and STDERR are kept separate when testing Black via its CLI."""
 
     def __init__(self) -> None:
-        self.stderrbuf = BytesIO()
-        self.stdoutbuf = BytesIO()
-        self.stdout_bytes = b""
-        self.stderr_bytes = b""
-        super().__init__()
-
-    @contextmanager
-    def isolation(self, *args: Any, **kwargs: Any) -> Generator[BinaryIO, None, None]:
-        with super().isolation(*args, **kwargs) as output:
-            try:
-                hold_stderr = sys.stderr
-                sys.stderr = TextIOWrapper(self.stderrbuf, encoding=self.charset)
-                yield output
-            finally:
-                self.stdout_bytes = sys.stdout.buffer.getvalue()  # type: ignore
-                self.stderr_bytes = sys.stderr.buffer.getvalue()  # type: ignore
-                sys.stderr = hold_stderr
+        super().__init__(mix_stderr=False)
+
+
+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
 
 
 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)
-        self.assertEqual(
-            result.exit_code,
-            exit_code,
-            msg=(
-                f"Failed with args: {args}\n"
-                f"stdout: {runner.stdout_bytes.decode()!r}\n"
-                f"stderr: {runner.stderr_bytes.decode()!r}\n"
-                f"exception: {result.exception}"
-            ),
-        )
-
-    @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)
+    invokeBlack = staticmethod(invokeBlack)
 
     def test_empty_ff(self) -> None:
         expected = ""
@@ -171,8 +157,9 @@ class BlackTestCase(BlackBaseTestCase):
         )
         self.assertEqual(result.exit_code, 0)
         self.assertFormatEqual(expected, result.output)
-        black.assert_equivalent(source, result.output)
-        black.assert_stable(source, result.output, DEFAULT_MODE)
+        if source != result.output:
+            black.assert_equivalent(source, result.output)
+            black.assert_stable(source, result.output, DEFAULT_MODE)
 
     def test_piping_diff(self) -> None:
         diff_header = re.compile(
@@ -273,32 +260,6 @@ class BlackTestCase(BlackBaseTestCase):
         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")
         root = black.lib2to3_parse(source)
@@ -368,15 +329,6 @@ class BlackTestCase(BlackBaseTestCase):
         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")
         root = black.lib2to3_parse(source)
@@ -389,52 +341,13 @@ class BlackTestCase(BlackBaseTestCase):
     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)
+        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)
-
-    @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_magic_trailing_comma(self) -> None:
         source, _ = read_data("expression.py")
         expected, _ = read_data("expression_skip_magic_trailing_comma.diff")
@@ -460,51 +373,6 @@ class BlackTestCase(BlackBaseTestCase):
             )
             self.assertEqual(expected, actual, msg)
 
-    @pytest.mark.without_python2
-    def test_python2_should_fail_without_optional_install(self) -> None:
-        # python 3.7 and below will install typed-ast and will be able to parse Python 2
-        if sys.version_info < (3, 8):
-            return
-        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)
-        actual = (
-            runner.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()
@@ -535,26 +403,6 @@ 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"
@@ -578,7 +426,7 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertFormatEqual(contents_spc, fs(contents_tab))
 
     def test_report_verbose(self) -> None:
-        report = black.Report(verbose=True)
+        report = Report(verbose=True)
         out_lines = []
         err_lines = []
 
@@ -588,7 +436,7 @@ class BlackTestCase(BlackBaseTestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
+        with patch("black.output._out", out), patch("black.output._err", err):
             report.done(Path("f1"), black.Changed.NO)
             self.assertEqual(len(out_lines), 1)
             self.assertEqual(len(err_lines), 0)
@@ -680,7 +528,7 @@ class BlackTestCase(BlackBaseTestCase):
             )
 
     def test_report_quiet(self) -> None:
-        report = black.Report(quiet=True)
+        report = Report(quiet=True)
         out_lines = []
         err_lines = []
 
@@ -690,7 +538,7 @@ class BlackTestCase(BlackBaseTestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
+        with patch("black.output._out", out), patch("black.output._err", err):
             report.done(Path("f1"), black.Changed.NO)
             self.assertEqual(len(out_lines), 0)
             self.assertEqual(len(err_lines), 0)
@@ -784,7 +632,7 @@ class BlackTestCase(BlackBaseTestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
+        with patch("black.output._out", out), patch("black.output._err", err):
             report.done(Path("f1"), black.Changed.NO)
             self.assertEqual(len(out_lines), 0)
             self.assertEqual(len(err_lines), 0)
@@ -958,6 +806,10 @@ class BlackTestCase(BlackBaseTestCase):
         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})
 
     def test_get_future_imports(self) -> None:
         node = black.lib2to3_parse("\n")
@@ -989,6 +841,7 @@ 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")
@@ -1001,8 +854,8 @@ class BlackTestCase(BlackBaseTestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
-            black.DebugVisitor.show(source)
+        with patch("black.debug.out", out):
+            DebugVisitor.show(source)
         actual = "\n".join(out_lines) + "\n"
         log_name = ""
         if expected != actual:
@@ -1039,6 +892,7 @@ class BlackTestCase(BlackBaseTestCase):
         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 = []
@@ -1050,7 +904,7 @@ class BlackTestCase(BlackBaseTestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
+        with patch("black.output._out", out), patch("black.output._err", err):
             with self.assertRaises(AssertionError):
                 self.assertFormatEqual("j = [1, 2, 3]", "j = [1, 2, 3,]")
 
@@ -1059,275 +913,86 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertTrue("Actual tree:" in out_str)
         self.assertEqual("".join(err_lines), "")
 
-    def test_cache_broken_file(self) -> None:
-        mode = DEFAULT_MODE
-        with cache_dir() as workspace:
-            cache_file = black.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("black.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')
+            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 = (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_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 = black.get_cache_file(mode)
-                self.assertFalse(cache_file.exists())
-                write_cache.assert_not_called()
-                read_cache.assert_not_called()
+    def test_no_files(self) -> None:
+        with cache_dir():
+            # Without an argument, black exits with error code 0.
+            self.invokeBlack([])
 
-    def test_no_cache_when_writeback_color_diff(self) -> None:
-        mode = DEFAULT_MODE
+    def test_broken_symlink(self) -> None:
         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 = black.get_cache_file(mode)
-                self.assertFalse(cache_file.exists())
-                write_cache.assert_not_called()
-                read_cache.assert_not_called()
+            symlink = workspace / "broken_link.py"
+            try:
+                symlink.symlink_to("nonexistent.py")
+            except (OSError, NotImplementedError) as e:
+                self.skipTest(f"Can't create symlinks: {e}")
+            self.invokeBlack([str(workspace.resolve())])
 
-    @event_loop()
-    def test_output_locking_when_writeback_diff(self) -> None:
+    def test_single_file_force_pyi(self) -> None:
+        pyi_mode = replace(DEFAULT_MODE, is_pyi=True)
+        contents, expected = read_data("force_pyi")
         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()
+            path = (workspace / "file.py").resolve()
+            with open(path, "w") as fh:
+                fh.write(contents)
+            self.invokeBlack([str(path), "--pyi"])
+            with open(path, "r") as fh:
+                actual = fh.read()
+            # verify cache with --pyi is separate
+            pyi_cache = black.read_cache(pyi_mode)
+            self.assertIn(str(path), pyi_cache)
+            normal_cache = black.read_cache(DEFAULT_MODE)
+            self.assertNotIn(str(path), normal_cache)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(contents, actual)
+        black.assert_stable(contents, actual, pyi_mode)
 
     @event_loop()
-    def test_output_locking_when_writeback_color_diff(self) -> None:
+    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")
         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 = black.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_broken_symlink(self) -> None:
-        with cache_dir() as workspace:
-            symlink = workspace / "broken_link.py"
-            try:
-                symlink.symlink_to("nonexistent.py")
-            except OSError 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")
-        with cache_dir() as workspace:
-            path = (workspace / "file.py").resolve()
-            with open(path, "w") as fh:
-                fh.write(contents)
-            self.invokeBlack([str(path), "--pyi"])
-            with open(path, "r") as fh:
-                actual = fh.read()
-            # verify cache with --pyi is separate
-            pyi_cache = black.read_cache(pyi_mode)
-            self.assertIn(str(path), pyi_cache)
-            normal_cache = black.read_cache(DEFAULT_MODE)
-            self.assertNotIn(str(path), normal_cache)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(contents, actual)
-        black.assert_stable(contents, actual, pyi_mode)
-
-    @event_loop()
-    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")
-        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)
-            self.invokeBlack([str(p) for p in paths] + ["--pyi"])
-            for path in paths:
-                with open(path, "r") as fh:
-                    actual = fh.read()
-                self.assertEqual(actual, expected)
-            # verify cache with --pyi is separate
-            pyi_cache = black.read_cache(pyi_mode)
-            normal_cache = black.read_cache(reg_mode)
-            for path in paths:
-                self.assertIn(str(path), pyi_cache)
-                self.assertNotIn(str(path), normal_cache)
+            paths = [
+                (workspace / "file1.py").resolve(),
+                (workspace / "file2.py").resolve(),
+            ]
+            for path in paths:
+                with open(path, "w") as fh:
+                    fh.write(contents)
+            self.invokeBlack([str(p) for p in paths] + ["--pyi"])
+            for path in paths:
+                with open(path, "r") as fh:
+                    actual = fh.read()
+                self.assertEqual(actual, expected)
+            # verify cache with --pyi is separate
+            pyi_cache = black.read_cache(pyi_mode)
+            normal_cache = black.read_cache(reg_mode)
+            for path in paths:
+                self.assertIn(str(path), pyi_cache)
+                self.assertNotIn(str(path), normal_cache)
 
     def test_pipe_force_pyi(self) -> None:
         source, expected = read_data("force_pyi")
@@ -1392,188 +1057,7 @@ class BlackTestCase(BlackBaseTestCase):
         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))
-
-    @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 mimicing 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",
@@ -1591,6 +1075,7 @@ 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",
@@ -1613,6 +1098,7 @@ 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",
@@ -1637,17 +1123,14 @@ class BlackTestCase(BlackBaseTestCase):
             # __BLACK_STDIN_FILENAME__ should have been stripped
             report.done.assert_called_with(expected, black.Changed.YES)
 
-    def test_reformat_one_with_stdin_and_existing_path(self) -> None:
+    @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()
-            # 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"))
-            # Make sure is_file actually returns True
-            self.assertTrue(p.is_file())
+            p = "foo.ipynb"
             path = Path(f"__BLACK_STDIN_FILENAME__{p}")
             expected = Path(p)
             black.reformat_one(
@@ -1657,98 +1140,67 @@ class BlackTestCase(BlackBaseTestCase):
                 mode=DEFAULT_MODE,
                 report=report,
             )
-            fsts.assert_called_once()
+            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)
 
-    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_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"),
-        ]
-        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,
+    @pytest.mark.incompatible_with_mypyc
+    def test_reformat_one_with_stdin_and_existing_path(self) -> None:
+        with patch(
+            "black.format_stdin_to_stdout",
+            return_value=lambda *args, **kwargs: black.Changed.YES,
+        ) as fsts:
+            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"))
+            # Make sure is_file actually returns True
+            self.assertTrue(p.is_file())
+            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,
             )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
+            fsts.assert_called_once()
+            # __BLACK_STDIN_FILENAME__ should have been stripped
+            report.done.assert_called_with(expected, black.Changed.YES)
 
-    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_reformat_one_with_stdin_empty(self) -> None:
+        output = io.StringIO()
+        with patch("io.TextIOWrapper", lambda *args, **kwargs: output):
+            try:
+                black.format_stdin_to_stdout(
+                    fast=True,
+                    content="",
+                    write_back=black.WriteBack.YES,
+                    mode=DEFAULT_MODE,
+                )
+            except io.UnsupportedOperation:
+                pass  # StringIO does not support detach
+            assert output.getvalue() == ""
 
     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
+        )
+
+    def test_required_version_does_not_match_version(self) -> None:
+        self.invokeBlack(
+            ["--required-version", "20.99b"], exit_code=1, ignore_config=True
+        )
+
     def test_preserves_line_endings(self) -> None:
         with TemporaryDirectory() as workspace:
             test_file = Path(workspace) / "test.py"
@@ -1769,7 +1221,7 @@ class BlackTestCase(BlackBaseTestCase):
                 black.main, ["-", "--fast"], input=BytesIO(contents.encode("utf8"))
             )
             self.assertEqual(result.exit_code, 0)
-            output = runner.stdout_bytes
+            output = result.stdout_bytes
             self.assertIn(nl.encode("utf8"), output)
             if nl == "\n":
                 self.assertNotIn(b"\r\n", output)
@@ -1778,64 +1230,9 @@ class BlackTestCase(BlackBaseTestCase):
         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  # type: ignore
+            from click import _unicodefun
         except ModuleNotFoundError:
             self.skipTest("Incompatible Click version")
         if not hasattr(_unicodefun, "_verify_python3_env"):
@@ -1844,14 +1241,14 @@ class BlackTestCase(BlackBaseTestCase):
         with patch("locale.getpreferredencoding") as gpe:
             gpe.return_value = "ASCII"
             with self.assertRaises(RuntimeError):
-                _unicodefun._verify_python3_env()
+                _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()
+                _unicodefun._verify_python3_env()  # type: ignore
             except RuntimeError as re:
                 self.fail(f"`patch_click()` failed, exception still raised: {re}")
 
@@ -1868,7 +1265,7 @@ class BlackTestCase(BlackBaseTestCase):
             critical=fail,
             log=fail,
         ):
-            ff(THIS_FILE)
+            ff(THIS_DIR / "util.py")
 
     def test_invalid_config_return_code(self) -> None:
         tmp_file = Path(black.dump_to_file())
@@ -1906,6 +1303,7 @@ class BlackTestCase(BlackBaseTestCase):
         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)
@@ -1928,7 +1326,10 @@ class BlackTestCase(BlackBaseTestCase):
             self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
             self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
 
-    @patch("black.find_user_pyproject_toml", black.find_user_pyproject_toml.__wrapped__)
+    @patch(
+        "black.files.find_user_pyproject_toml",
+        black.files.find_user_pyproject_toml.__wrapped__,
+    )
     def test_find_user_pyproject_toml_linux(self) -> None:
         if system() == "Windows":
             return
@@ -1938,7 +1339,7 @@ class BlackTestCase(BlackBaseTestCase):
             tmp_user_config = Path(workspace) / "black"
             with patch.dict("os.environ", {"XDG_CONFIG_HOME": workspace}):
                 self.assertEqual(
-                    black.find_user_pyproject_toml(), tmp_user_config.resolve()
+                    black.files.find_user_pyproject_toml(), tmp_user_config.resolve()
                 )
 
         # Test fallback for XDG_CONFIG_HOME
@@ -1946,7 +1347,7 @@ class BlackTestCase(BlackBaseTestCase):
             os.environ.pop("XDG_CONFIG_HOME", None)
             fallback_user_config = Path("~/.config").expanduser() / "black"
             self.assertEqual(
-                black.find_user_pyproject_toml(), fallback_user_config.resolve()
+                black.files.find_user_pyproject_toml(), fallback_user_config.resolve()
             )
 
     def test_find_user_pyproject_toml_windows(self) -> None:
@@ -1954,24 +1355,21 @@ class BlackTestCase(BlackBaseTestCase):
             return
 
         user_config_path = Path.home() / ".black"
-        self.assertEqual(black.find_user_pyproject_toml(), user_config_path.resolve())
+        self.assertEqual(
+            black.files.find_user_pyproject_toml(), user_config_path.resolve()
+        )
 
     def test_bpo_33660_workaround(self) -> None:
         if system() == "Windows":
             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_newline_comment_interaction(self) -> None:
         source = "class A:\\\r\n# type: ignore\n pass\n"
@@ -2011,22 +1409,676 @@ class BlackTestCase(BlackBaseTestCase):
         )
         expected = 'def foo():\n    """Testing\n    Testing"""\n    print "Foo"\n'
 
-        result = CliRunner().invoke(
+        result = BlackRunner().invoke(
             black.main,
             ["-", "-q", "--target-version=py27"],
             input=BytesIO(source),
         )
 
         self.assertEqual(result.exit_code, 0)
-        actual = result.output
+        actual = result.stdout
         self.assertFormatEqual(actual, expected)
 
+    @staticmethod
+    def compare_results(
+        result: click.testing.Result, expected_value: str, expected_exit_code: int
+    ) -> None:
+        """Helper method to test the value and exit code of a click Result."""
+        assert (
+            result.output == expected_value
+        ), "The output did not match the expected value."
+        assert result.exit_code == expected_exit_code, "The exit code is incorrect."
+
+    def test_code_option(self) -> None:
+        """Test the code option with no changes."""
+        code = 'print("Hello world")\n'
+        args = ["--code", code]
+        result = CliRunner().invoke(black.main, args)
+
+        self.compare_results(result, code, 0)
+
+    def test_code_option_changed(self) -> None:
+        """Test the code option when changes are required."""
+        code = "print('hello world')"
+        formatted = black.format_str(code, mode=DEFAULT_MODE)
+
+        args = ["--code", code]
+        result = CliRunner().invoke(black.main, args)
+
+        self.compare_results(result, formatted, 0)
+
+    def test_code_option_check(self) -> None:
+        """Test the code option when check is passed."""
+        args = ["--check", "--code", 'print("Hello world")\n']
+        result = CliRunner().invoke(black.main, args)
+        self.compare_results(result, "", 0)
+
+    def test_code_option_check_changed(self) -> None:
+        """Test the code option when changes are required, and check is passed."""
+        args = ["--check", "--code", "print('hello world')"]
+        result = CliRunner().invoke(black.main, args)
+        self.compare_results(result, "", 1)
+
+    def test_code_option_diff(self) -> None:
+        """Test the code option when diff is passed."""
+        code = "print('hello world')"
+        formatted = black.format_str(code, mode=DEFAULT_MODE)
+        result_diff = diff(code, formatted, "STDIN", "STDOUT")
+
+        args = ["--diff", "--code", code]
+        result = CliRunner().invoke(black.main, args)
+
+        # Remove time from diff
+        output = DIFF_TIME.sub("", result.output)
+
+        assert output == result_diff, "The output did not match the expected value."
+        assert result.exit_code == 0, "The exit code is incorrect."
+
+    def test_code_option_color_diff(self) -> None:
+        """Test the code option when color and diff are passed."""
+        code = "print('hello world')"
+        formatted = black.format_str(code, mode=DEFAULT_MODE)
+
+        result_diff = diff(code, formatted, "STDIN", "STDOUT")
+        result_diff = color_diff(result_diff)
+
+        args = ["--diff", "--color", "--code", code]
+        result = CliRunner().invoke(black.main, args)
+
+        # Remove time from diff
+        output = DIFF_TIME.sub("", result.output)
+
+        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
+        with patch.object(black, "assert_equivalent", side_effect=AssertionError):
+            code = 'print("Hello world")'
+            error_msg = f"{code}\nerror: cannot format <string>: \n"
+
+            args = ["--safe", "--code", code]
+            result = CliRunner().invoke(black.main, args)
+
+            self.compare_results(result, error_msg, 123)
+
+    def test_code_option_fast(self) -> None:
+        """Test that the code option ignores errors when the sanity checks fail."""
+        # Patch black.assert_equivalent to ensure the sanity checks fail
+        with patch.object(black, "assert_equivalent", side_effect=AssertionError):
+            code = 'print("Hello world")'
+            formatted = black.format_str(code, mode=DEFAULT_MODE)
+
+            args = ["--fast", "--code", code]
+            result = CliRunner().invoke(black.main, args)
+
+            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:
+            args = ["--code", "print"]
+            # 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()
+
+            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."
+
+    @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:
+            with change_directory(THIS_DIR):
+                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."
+
+                _, 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")
+
+
+class TestCaching:
+    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")
+            assert black.read_cache(mode) == {}
+            src = (workspace / "test.py").resolve()
+            src.write_text("print('hello')")
+            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')")
+            black.write_cache({}, [src], mode)
+            invokeBlack([str(src)])
+            assert src.read_text() == "print('hello')"
+
+    @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)
+            invokeBlack([str(workspace)])
+            with one.open("r") as fobj:
+                assert fobj.read() == "print('hello')"
+            with two.open("r") as fobj:
+                assert fobj.read() == '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()
+            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:
+                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()
+                with src.open("w") as fobj:
+                    fobj.write("print('hello')")
+            with patch("black.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.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(
+            "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')
+            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]],
+    *,
+    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=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?$",
+            exclude=r"/exclude/|/\.definitely_exclude/",
+        )
+
+    def test_gitignore_used_as_default(self) -> None:
+        base = Path(DATA_DIR / "include_exclude_tests")
+        expected = [
+            base / "b/.definitely_exclude/a.py",
+            base / "b/.definitely_exclude/a.pyi",
+        ]
+        src = [base / "b/"]
+        assert_collected_sources(src, expected, extend_exclude=r"/exclude/")
+
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    def test_exclude_for_issue_1572(self) -> None:
+        # Exclude shouldn't touch files that were explicitly given to Black through the
+        # CLI. Exclude is supposed to only apply to the recursive discovery of files.
+        # https://github.com/psf/black/issues/1572
+        path = DATA_DIR / "include_exclude_tests"
+        src = [path / "b/exclude/a.py"]
+        expected = [path / "b/exclude/a.py"]
+        assert_collected_sources(src, expected, include="", exclude=r"/exclude/|a\.py")
+
+    def test_gitignore_exclude(self) -> None:
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        include = re.compile(r"\.pyi?$")
+        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,
+                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,
+                root_gitignore,
+                verbose=False,
+                quiet=False,
+            )
+        )
+        assert sorted(expected) == sorted(sources)
+
+    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_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"
+        child.is_symlink.return_value = True
+        try:
+            list(
+                black.gen_python_files(
+                    path.iterdir(),
+                    root,
+                    include,
+                    exclude,
+                    None,
+                    None,
+                    report,
+                    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()
+        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 pytest.raises(ValueError):
+            list(
+                black.gen_python_files(
+                    path.iterdir(),
+                    root,
+                    include,
+                    exclude,
+                    None,
+                    None,
+                    report,
+                    gitignore,
+                    verbose=False,
+                    quiet=False,
+                )
+            )
+        path.iterdir.assert_called()
+        assert path.iterdir.call_count == 2
+        child.resolve.assert_called()
+        assert child.resolve.call_count == 2
+        child.is_symlink.assert_called()
+        assert child.is_symlink.call_count == 2
+
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    def test_get_sources_with_stdin(self) -> None:
+        src = ["-"]
+        expected = ["-"]
+        assert_collected_sources(src, expected, include="", exclude=r"/exclude/|a\.py")
 
-with open(black.__file__, "r", encoding="utf-8") as _bf:
-    black_source_lines = _bf.readlines()
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    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())
+    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())
+    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())
+    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,
+        )
 
-def tracefunc(frame: types.FrameType, event: str, arg: Any) -> Callable:
+
+@pytest.mark.python2
+@pytest.mark.parametrize("explicit", [True, False], ids=["explicit", "autodetection"])
+def test_python_2_deprecation_with_target_version(explicit: bool) -> None:
+    args = [
+        "--config",
+        str(THIS_DIR / "empty.toml"),
+        str(DATA_DIR / "python2.py"),
+        "--check",
+    ]
+    if explicit:
+        args.append("--target-version=py27")
+    with cache_dir():
+        result = BlackRunner().invoke(black.main, args)
+    assert "DEPRECATION: Python 2 support will be removed" in result.stderr
+
+
+@pytest.mark.python2
+def test_python_2_deprecation_autodetection_extended() -> None:
+    # this test has a similar construction to test_get_features_used_decorator
+    python2, non_python2 = read_data("python2_detection")
+    for python2_case in python2.split("###"):
+        node = black.lib2to3_parse(python2_case)
+        assert black.detect_target_versions(node) == {TargetVersion.PY27}, python2_case
+    for non_python2_case in non_python2.split("###"):
+        node = black.lib2to3_parse(non_python2_case)
+        assert black.detect_target_versions(node) != {
+            TargetVersion.PY27
+        }, non_python2_case
+
+
+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[[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.
@@ -2046,7 +2098,3 @@ 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")