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Bump typed-ast minimum to 1.4.3 for 3.10 compat (#2519)
[etc/vim.git] / tests / test_black.py
index f0a14aa2da4ead177d897ef9402a33ea1d0e46ea..f25db1b73d1ef9b102cce37ae1c89fe3566efbb4 100644 (file)
@@ -1,66 +1,70 @@
 #!/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
-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,
     TypeVar,
+    Union,
 )
-import pytest
-import unittest
-from unittest.mock import patch, MagicMock
+from unittest.mock import MagicMock, patch
 
 import click
+import pytest
+import regex as 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 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 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,
+    PY36_VERSIONS,
+    THIS_DIR,
     BlackBaseTestCase,
-    DEFAULT_MODE,
-    fs,
-    ff,
+    assert_format,
+    change_directory,
     dump_to_stderr,
+    ff,
+    fs,
+    read_data,
 )
 
-
 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")
 
@@ -111,32 +115,26 @@ 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)
-        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)
+    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 = ""
@@ -261,32 +259,6 @@ 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)
@@ -356,15 +328,6 @@ 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)
@@ -377,52 +340,13 @@ 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")
@@ -448,55 +372,6 @@ class BlackTestCase(BlackBaseTestCase):
             )
             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)
-        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()
@@ -527,26 +402,6 @@ 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"
@@ -1051,256 +906,67 @@ 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 = 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 = 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 = 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 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:
-        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_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")
+    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(),
@@ -1384,214 +1050,6 @@ 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?$")
-        exclude = re.compile(r"/exclude/|/\.definitely_exclude/")
-        report = black.Report()
-        gitignore = PathSpec.from_lines("gitwildmatch", [])
-        sources: List[Path] = []
-        expected = [
-            Path(path / "b/dont_exclude/a.py"),
-            Path(path / "b/dont_exclude/a.pyi"),
-        ]
-        this_abs = THIS_DIR.resolve()
-        sources.extend(
-            black.gen_python_files(
-                path.iterdir(),
-                this_abs,
-                include,
-                exclude,
-                None,
-                None,
-                report,
-                gitignore,
-            )
-        )
-        self.assertEqual(sorted(expected), sorted(sources))
-
-    def test_gitignore_used_as_default(self) -> None:
-        path = Path(THIS_DIR / "data" / "include_exclude_tests")
-        include = re.compile(r"\.pyi?$")
-        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))
-
     def test_reformat_one_with_stdin(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",
@@ -1655,6 +1113,30 @@ 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_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)
+
     def test_reformat_one_with_stdin_and_existing_path(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",
@@ -1679,122 +1161,33 @@ class BlackTestCase(BlackBaseTestCase):
             # __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_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_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_invalid_cli_regex(self) -> None:
+        for option in ["--include", "--exclude", "--extend-exclude", "--force-exclude"]:
+            self.invokeBlack(["-", option, "**()(!!*)"], exit_code=2)
 
-    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,
-            )
+    def test_required_version_matches_version(self) -> None:
+        self.invokeBlack(
+            ["--required-version", black.__version__], exit_code=0, ignore_config=True
         )
-        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,
-            )
+    def test_required_version_does_not_match_version(self) -> None:
+        self.invokeBlack(
+            ["--required-version", "20.99b"], exit_code=1, ignore_config=True
         )
-        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_preserves_line_endings(self) -> None:
         with TemporaryDirectory() as workspace:
@@ -1825,64 +1218,9 @@ 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"):
@@ -1891,14 +1229,14 @@ 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}")
 
@@ -2013,17 +1351,12 @@ 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_newline_comment_interaction(self) -> None:
         source = "class A:\\\r\n# type: ignore\n pass\n"
@@ -2174,10 +1507,6 @@ class BlackTestCase(BlackBaseTestCase):
         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)
 
@@ -2196,22 +1525,489 @@ class BlackTestCase(BlackBaseTestCase):
         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(Path("tests")):
+                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."
+
+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(list(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"
+        )
+
+    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")
+
+    @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,
+        )
 
 
 with open(black.__file__, "r", encoding="utf-8") as _bf:
@@ -2238,7 +2034,3 @@ 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")