Move imports of `ThreadPoolExecutor` into `reformat_many()`, allowing Black-in-the...

[etc/vim.git] / tests / test_black.py

diff --git a/tests/test_black.py b/tests/test_black.py
index 301a3a5b3637a3b2a0c43031b43269e238bfa72e..74334d267a1f7a70a9f6a563da376354fd8743c1 100644 (file)
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -10,7 +10,7 @@ import sys
 import types
 import unittest
 from concurrent.futures import ThreadPoolExecutor
 import types
 import unittest
 from concurrent.futures import ThreadPoolExecutor

-from contextlib import contextmanager
+from contextlib import contextmanager, redirect_stderr

 from dataclasses import replace
 from io import BytesIO
 from pathlib import Path
 from dataclasses import replace
 from io import BytesIO
 from pathlib import Path


@@ -31,7 +31,7 @@ from unittest.mock import MagicMock, patch
 
 import click
 import pytest
 
 import click
 import pytest

-import regex as re
+import re

 from click import unstyle
 from click.testing import CliRunner
 from pathspec import PathSpec
 from click import unstyle
 from click.testing import CliRunner
 from pathspec import PathSpec


@@ -40,7 +40,7 @@ import black
 import black.files
 from black import Feature, TargetVersion
 from black import re_compile_maybe_verbose as compile_pattern
 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.cache import get_cache_dir, get_cache_file

 from black.debug import DebugVisitor
 from black.output import color_diff, diff
 from black.report import Report
 from black.debug import DebugVisitor
 from black.output import color_diff, diff
 from black.report import Report


@@ -63,6 +63,7 @@ from tests.util import (
 )
 
 THIS_FILE = Path(__file__)
 )
 
 THIS_FILE = Path(__file__)

+EMPTY_CONFIG = THIS_DIR / "data" / "empty_pyproject.toml"

 PY36_ARGS = [f"--target-version={version.name.lower()}" for version in PY36_VERSIONS]
 DEFAULT_EXCLUDE = black.re_compile_maybe_verbose(black.const.DEFAULT_EXCLUDES)
 DEFAULT_INCLUDE = black.re_compile_maybe_verbose(black.const.DEFAULT_INCLUDES)
 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)


@@ -70,7 +71,7 @@ T = TypeVar("T")
 R = TypeVar("R")
 
 # Match the time output in a diff, but nothing else
 R = TypeVar("R")
 
 # Match the time output in a diff, but nothing else

-DIFF_TIME = re.compile(r"\t[\d-:+\. ]+")
+DIFF_TIME = re.compile(r"\t[\d\-:+\. ]+")

 
 
 @contextmanager
 
 
 @contextmanager


@@ -100,6 +101,8 @@ class FakeContext(click.Context):
 
     def __init__(self) -> None:
         self.default_map: Dict[str, Any] = {}
 
     def __init__(self) -> None:
         self.default_map: Dict[str, Any] = {}

+        # Dummy root, since most of the tests don't care about it
+        self.obj: Dict[str, Any] = {"root": PROJECT_ROOT}

 
 
 class FakeParameter(click.Parameter):
 
 
 class FakeParameter(click.Parameter):


@@ -122,7 +125,7 @@ def invokeBlack(
     runner = BlackRunner()
     if ignore_config:
         args = ["--verbose", "--config", str(THIS_DIR / "empty.toml"), *args]
     runner = BlackRunner()
     if ignore_config:
         args = ["--verbose", "--config", str(THIS_DIR / "empty.toml"), *args]

-    result = runner.invoke(black.main, 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 = (
     assert result.stdout_bytes is not None
     assert result.stderr_bytes is not None
     msg = (


@@ -148,11 +151,21 @@ class BlackTestCase(BlackBaseTestCase):
             os.unlink(tmp_file)
         self.assertFormatEqual(expected, actual)
 
             os.unlink(tmp_file)
         self.assertFormatEqual(expected, actual)
 

+    def test_experimental_string_processing_warns(self) -> None:
+        self.assertWarns(
+            black.mode.Deprecated, black.Mode, experimental_string_processing=True
+        )
+

     def test_piping(self) -> None:
         source, expected = read_data("src/black/__init__", data=False)
         result = BlackRunner().invoke(
             black.main,
     def test_piping(self) -> None:
         source, expected = read_data("src/black/__init__", data=False)
         result = BlackRunner().invoke(
             black.main,

-            ["-", "--fast", f"--line-length={black.DEFAULT_LINE_LENGTH}"],
+            [
+                "-",
+                "--fast",
+                f"--line-length={black.DEFAULT_LINE_LENGTH}",
+                f"--config={EMPTY_CONFIG}",
+            ],

             input=BytesIO(source.encode("utf8")),
         )
         self.assertEqual(result.exit_code, 0)
             input=BytesIO(source.encode("utf8")),
         )
         self.assertEqual(result.exit_code, 0)


@@ -168,13 +181,12 @@ class BlackTestCase(BlackBaseTestCase):
         )
         source, _ = read_data("expression.py")
         expected, _ = read_data("expression.diff")
         )
         source, _ = read_data("expression.py")
         expected, _ = read_data("expression.diff")

-        config = THIS_DIR / "data" / "empty_pyproject.toml"

         args = [
             "-",
             "--fast",
             f"--line-length={black.DEFAULT_LINE_LENGTH}",
             "--diff",
         args = [
             "-",
             "--fast",
             f"--line-length={black.DEFAULT_LINE_LENGTH}",
             "--diff",

-            f"--config={config}",
+            f"--config={EMPTY_CONFIG}",

         ]
         result = BlackRunner().invoke(
             black.main, args, input=BytesIO(source.encode("utf8"))
         ]
         result = BlackRunner().invoke(
             black.main, args, input=BytesIO(source.encode("utf8"))


@@ -186,21 +198,20 @@ class BlackTestCase(BlackBaseTestCase):
 
     def test_piping_diff_with_color(self) -> None:
         source, _ = read_data("expression.py")
 
     def test_piping_diff_with_color(self) -> None:
         source, _ = read_data("expression.py")

-        config = THIS_DIR / "data" / "empty_pyproject.toml"

         args = [
             "-",
             "--fast",
             f"--line-length={black.DEFAULT_LINE_LENGTH}",
             "--diff",
             "--color",
         args = [
             "-",
             "--fast",
             f"--line-length={black.DEFAULT_LINE_LENGTH}",
             "--diff",
             "--color",

-            f"--config={config}",
+            f"--config={EMPTY_CONFIG}",

         ]
         result = BlackRunner().invoke(
             black.main, args, input=BytesIO(source.encode("utf8"))
         )
         actual = result.output
         # Again, the contents are checked in a different test, so only look for colors.
         ]
         result = BlackRunner().invoke(
             black.main, args, input=BytesIO(source.encode("utf8"))
         )
         actual = result.output
         # Again, the contents are checked in a different test, so only look for colors.

-        self.assertIn("\033[1;37m", actual)
+        self.assertIn("\033[1m", actual)

         self.assertIn("\033[36m", actual)
         self.assertIn("\033[32m", actual)
         self.assertIn("\033[31m", actual)
         self.assertIn("\033[36m", actual)
         self.assertIn("\033[32m", actual)
         self.assertIn("\033[31m", actual)


@@ -221,45 +232,6 @@ class BlackTestCase(BlackBaseTestCase):
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, black.FileMode())
 
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, black.FileMode())
 

-    @unittest.expectedFailure
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability1(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens1")
-        actual = fs(source)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @unittest.expectedFailure
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability2(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens2")
-        actual = fs(source)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @unittest.expectedFailure
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability3(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens3")
-        actual = fs(source)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability1_pass2(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens1")
-        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability2_pass2(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens2")
-        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_trailing_comma_optional_parens_stability3_pass2(self) -> None:
-        source, _expected = read_data("trailing_comma_optional_parens3")
-        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
-        black.assert_stable(source, actual, DEFAULT_MODE)
-

     def test_pep_572_version_detection(self) -> None:
         source, _ = read_data("pep_572")
         root = black.lib2to3_parse(source)
     def test_pep_572_version_detection(self) -> None:
         source, _ = read_data("pep_572")
         root = black.lib2to3_parse(source)


@@ -284,7 +256,6 @@ class BlackTestCase(BlackBaseTestCase):
 
     def test_expression_diff(self) -> None:
         source, _ = read_data("expression.py")
 
     def test_expression_diff(self) -> None:
         source, _ = read_data("expression.py")

-        config = THIS_DIR / "data" / "empty_pyproject.toml"

         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         diff_header = re.compile(
         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         diff_header = re.compile(


@@ -293,7 +264,7 @@ class BlackTestCase(BlackBaseTestCase):
         )
         try:
             result = BlackRunner().invoke(
         )
         try:
             result = BlackRunner().invoke(

-                black.main, ["--diff", str(tmp_file), f"--config={config}"]
+                black.main, ["--diff", str(tmp_file), f"--config={EMPTY_CONFIG}"]

             )
             self.assertEqual(result.exit_code, 0)
         finally:
             )
             self.assertEqual(result.exit_code, 0)
         finally:


@@ -311,19 +282,19 @@ class BlackTestCase(BlackBaseTestCase):
 
     def test_expression_diff_with_color(self) -> None:
         source, _ = read_data("expression.py")
 
     def test_expression_diff_with_color(self) -> None:
         source, _ = read_data("expression.py")

-        config = THIS_DIR / "data" / "empty_pyproject.toml"

         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         try:
             result = BlackRunner().invoke(
         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         try:
             result = BlackRunner().invoke(

-                black.main, ["--diff", "--color", str(tmp_file), f"--config={config}"]
+                black.main,
+                ["--diff", "--color", str(tmp_file), f"--config={EMPTY_CONFIG}"],

             )
         finally:
             os.unlink(tmp_file)
         actual = result.output
         # We check the contents of the diff in `test_expression_diff`. All
         # we need to check here is that color codes exist in the result.
             )
         finally:
             os.unlink(tmp_file)
         actual = result.output
         # We check the contents of the diff in `test_expression_diff`. All
         # we need to check here is that color codes exist in the result.

-        self.assertIn("\033[1;37m", actual)
+        self.assertIn("\033[1m", actual)

         self.assertIn("\033[36m", actual)
         self.assertIn("\033[32m", actual)
         self.assertIn("\033[31m", actual)
         self.assertIn("\033[36m", actual)
         self.assertIn("\033[32m", actual)
         self.assertIn("\033[31m", actual)


@@ -340,7 +311,7 @@ class BlackTestCase(BlackBaseTestCase):
     @patch("black.dump_to_file", dump_to_stderr)
     def test_string_quotes(self) -> None:
         source, expected = read_data("string_quotes")
     @patch("black.dump_to_file", dump_to_stderr)
     def test_string_quotes(self) -> None:
         source, expected = read_data("string_quotes")

-        mode = black.Mode(experimental_string_processing=True)
+        mode = black.Mode(preview=True)

         assert_format(source, expected, mode)
         mode = replace(mode, string_normalization=False)
         not_normalized = fs(source, mode=mode)
         assert_format(source, expected, mode)
         mode = replace(mode, string_normalization=False)
         not_normalized = fs(source, mode=mode)


@@ -357,7 +328,9 @@ class BlackTestCase(BlackBaseTestCase):
             r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
         )
         try:
             r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
         )
         try:

-            result = BlackRunner().invoke(black.main, ["-C", "--diff", str(tmp_file)])
+            result = BlackRunner().invoke(
+                black.main, ["-C", "--diff", str(tmp_file), f"--config={EMPTY_CONFIG}"]
+            )

             self.assertEqual(result.exit_code, 0)
         finally:
             os.unlink(tmp_file)
             self.assertEqual(result.exit_code, 0)
         finally:
             os.unlink(tmp_file)


@@ -724,24 +697,15 @@ class BlackTestCase(BlackBaseTestCase):
 
         straddling = "x + y"
         black.lib2to3_parse(straddling)
 
         straddling = "x + y"
         black.lib2to3_parse(straddling)

-        black.lib2to3_parse(straddling, {TargetVersion.PY27})

         black.lib2to3_parse(straddling, {TargetVersion.PY36})
         black.lib2to3_parse(straddling, {TargetVersion.PY36})

-        black.lib2to3_parse(straddling, {TargetVersion.PY27, TargetVersion.PY36})

 
         py2_only = "print x"
 
         py2_only = "print x"

-        black.lib2to3_parse(py2_only)
-        black.lib2to3_parse(py2_only, {TargetVersion.PY27})

         with self.assertRaises(black.InvalidInput):
             black.lib2to3_parse(py2_only, {TargetVersion.PY36})
         with self.assertRaises(black.InvalidInput):
             black.lib2to3_parse(py2_only, {TargetVersion.PY36})

-        with self.assertRaises(black.InvalidInput):
-            black.lib2to3_parse(py2_only, {TargetVersion.PY27, TargetVersion.PY36})

 
         py3_only = "exec(x, end=y)"
         black.lib2to3_parse(py3_only)
 
         py3_only = "exec(x, end=y)"
         black.lib2to3_parse(py3_only)

-        with self.assertRaises(black.InvalidInput):
-            black.lib2to3_parse(py3_only, {TargetVersion.PY27})

         black.lib2to3_parse(py3_only, {TargetVersion.PY36})
         black.lib2to3_parse(py3_only, {TargetVersion.PY36})

-        black.lib2to3_parse(py3_only, {TargetVersion.PY27, TargetVersion.PY36})

 
     def test_get_features_used_decorator(self) -> None:
         # Test the feature detection of new decorator syntax
 
     def test_get_features_used_decorator(self) -> None:
         # Test the feature detection of new decorator syntax


@@ -810,6 +774,50 @@ class BlackTestCase(BlackBaseTestCase):
         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})
         self.assertEqual(black.get_features_used(node), {Feature.POS_ONLY_ARGUMENTS})
         node = black.lib2to3_parse("def fn(a, /, b): ...")
         self.assertEqual(black.get_features_used(node), {Feature.POS_ONLY_ARGUMENTS})

+        node = black.lib2to3_parse("def fn(): yield a, b")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("def fn(): return a, b")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("def fn(): yield *b, c")
+        self.assertEqual(black.get_features_used(node), {Feature.UNPACKING_ON_FLOW})
+        node = black.lib2to3_parse("def fn(): return a, *b, c")
+        self.assertEqual(black.get_features_used(node), {Feature.UNPACKING_ON_FLOW})
+        node = black.lib2to3_parse("x = a, *b, c")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("x: Any = regular")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("x: Any = (regular, regular)")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("x: Any = Complex(Type(1))[something]")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("x: Tuple[int, ...] = a, b, c")
+        self.assertEqual(
+            black.get_features_used(node), {Feature.ANN_ASSIGN_EXTENDED_RHS}
+        )
+        node = black.lib2to3_parse("try: pass\nexcept Something: pass")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("try: pass\nexcept (*Something,): pass")
+        self.assertEqual(black.get_features_used(node), set())
+        node = black.lib2to3_parse("try: pass\nexcept *Group: pass")
+        self.assertEqual(black.get_features_used(node), {Feature.EXCEPT_STAR})
+
+    def test_get_features_used_for_future_flags(self) -> None:
+        for src, features in [
+            ("from __future__ import annotations", {Feature.FUTURE_ANNOTATIONS}),
+            (
+                "from __future__ import (other, annotations)",
+                {Feature.FUTURE_ANNOTATIONS},
+            ),
+            ("a = 1 + 2\nfrom something import annotations", set()),
+            ("from __future__ import x, y", set()),
+        ]:
+            with self.subTest(src=src, features=features):
+                node = black.lib2to3_parse(src)
+                future_imports = black.get_future_imports(node)
+                self.assertEqual(
+                    black.get_features_used(node, future_imports=future_imports),
+                    features,
+                )

 
     def test_get_future_imports(self) -> None:
         node = black.lib2to3_parse("\n")
 
     def test_get_future_imports(self) -> None:
         node = black.lib2to3_parse("\n")


@@ -841,6 +849,7 @@ class BlackTestCase(BlackBaseTestCase):
         )
         self.assertEqual({"unicode_literals", "print"}, black.get_future_imports(node))
 
         )
         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")
     def test_debug_visitor(self) -> None:
         source, _ = read_data("debug_visitor.py")
         expected, _ = read_data("debug_visitor.out")


@@ -891,6 +900,7 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertEqual(len(n.children), 1)
         self.assertEqual(n.children[0].type, black.token.ENDMARKER)
 
         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 = []
     @unittest.skipIf(os.environ.get("SKIP_AST_PRINT"), "user set SKIP_AST_PRINT")
     def test_assertFormatEqual(self) -> None:
         out_lines = []


@@ -907,12 +917,12 @@ class BlackTestCase(BlackBaseTestCase):
                 self.assertFormatEqual("j = [1, 2, 3]", "j = [1, 2, 3,]")
 
         out_str = "".join(out_lines)
                 self.assertFormatEqual("j = [1, 2, 3]", "j = [1, 2, 3,]")
 
         out_str = "".join(out_lines)

-        self.assertTrue("Expected tree:" in out_str)
-        self.assertTrue("Actual tree:" in out_str)
+        self.assertIn("Expected tree:", out_str)
+        self.assertIn("Actual tree:", out_str)

         self.assertEqual("".join(err_lines), "")
 
     @event_loop()
         self.assertEqual("".join(err_lines), "")
 
     @event_loop()

-    @patch("black.ProcessPoolExecutor", MagicMock(side_effect=OSError))
+    @patch("concurrent.futures.ProcessPoolExecutor", MagicMock(side_effect=OSError))

     def test_works_in_mono_process_only_environment(self) -> None:
         with cache_dir() as workspace:
             for f in [
     def test_works_in_mono_process_only_environment(self) -> None:
         with cache_dir() as workspace:
             for f in [


@@ -934,10 +944,13 @@ class BlackTestCase(BlackBaseTestCase):
             # Multi file command.
             self.invokeBlack([str(src1), str(src2), "--diff", "--check"], exit_code=1)
 
             # Multi file command.
             self.invokeBlack([str(src1), str(src2), "--diff", "--check"], exit_code=1)
 

-    def test_no_files(self) -> None:
+    def test_no_src_fails(self) -> None:

         with cache_dir():
         with cache_dir():

-            # Without an argument, black exits with error code 0.
-            self.invokeBlack([])
+            self.invokeBlack([], exit_code=1)
+
+    def test_src_and_code_fails(self) -> None:
+        with cache_dir():
+            self.invokeBlack([".", "-c", "0"], exit_code=1)

 
     def test_broken_symlink(self) -> None:
         with cache_dir() as workspace:
 
     def test_broken_symlink(self) -> None:
         with cache_dir() as workspace:


@@ -1055,6 +1068,7 @@ class BlackTestCase(BlackBaseTestCase):
         actual = result.output
         self.assertFormatEqual(actual, expected)
 
         actual = result.output
         self.assertFormatEqual(actual, expected)
 

+    @pytest.mark.incompatible_with_mypyc

     def test_reformat_one_with_stdin(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",
     def test_reformat_one_with_stdin(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",


@@ -1072,6 +1086,7 @@ class BlackTestCase(BlackBaseTestCase):
             fsts.assert_called_once()
             report.done.assert_called_with(path, black.Changed.YES)
 
             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",
     def test_reformat_one_with_stdin_filename(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",


@@ -1094,6 +1109,7 @@ class BlackTestCase(BlackBaseTestCase):
             # __BLACK_STDIN_FILENAME__ should have been stripped
             report.done.assert_called_with(expected, black.Changed.YES)
 
             # __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",
     def test_reformat_one_with_stdin_filename_pyi(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",


@@ -1118,6 +1134,7 @@ class BlackTestCase(BlackBaseTestCase):
             # __BLACK_STDIN_FILENAME__ should have been stripped
             report.done.assert_called_with(expected, black.Changed.YES)
 
             # __BLACK_STDIN_FILENAME__ should have been stripped
             report.done.assert_called_with(expected, black.Changed.YES)
 

+    @pytest.mark.incompatible_with_mypyc

     def test_reformat_one_with_stdin_filename_ipynb(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",
     def test_reformat_one_with_stdin_filename_ipynb(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",


@@ -1142,6 +1159,7 @@ class BlackTestCase(BlackBaseTestCase):
             # __BLACK_STDIN_FILENAME__ should have been stripped
             report.done.assert_called_with(expected, black.Changed.YES)
 
             # __BLACK_STDIN_FILENAME__ should have been stripped
             report.done.assert_called_with(expected, black.Changed.YES)
 

+    @pytest.mark.incompatible_with_mypyc

     def test_reformat_one_with_stdin_and_existing_path(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",
     def test_reformat_one_with_stdin_and_existing_path(self) -> None:
         with patch(
             "black.format_stdin_to_stdout",


@@ -1186,14 +1204,33 @@ class BlackTestCase(BlackBaseTestCase):
 
     def test_required_version_matches_version(self) -> None:
         self.invokeBlack(
 
     def test_required_version_matches_version(self) -> None:
         self.invokeBlack(

-            ["--required-version", black.__version__], exit_code=0, ignore_config=True
+            ["--required-version", black.__version__, "-c", "0"],
+            exit_code=0,
+            ignore_config=True,

         )
 
         )
 

-    def test_required_version_does_not_match_version(self) -> None:
+    def test_required_version_matches_partial_version(self) -> None:

         self.invokeBlack(
         self.invokeBlack(

-            ["--required-version", "20.99b"], exit_code=1, ignore_config=True
+            ["--required-version", black.__version__.split(".")[0], "-c", "0"],
+            exit_code=0,
+            ignore_config=True,

         )
 
         )
 

+    def test_required_version_does_not_match_on_minor_version(self) -> None:
+        self.invokeBlack(
+            ["--required-version", black.__version__.split(".")[0] + ".999", "-c", "0"],
+            exit_code=1,
+            ignore_config=True,
+        )
+
+    def test_required_version_does_not_match_version(self) -> None:
+        result = BlackRunner().invoke(
+            black.main,
+            ["--required-version", "20.99b", "-c", "0"],
+        )
+        self.assertEqual(result.exit_code, 1)
+        self.assertIn("required version", result.stderr)
+

     def test_preserves_line_endings(self) -> None:
         with TemporaryDirectory() as workspace:
             test_file = Path(workspace) / "test.py"
     def test_preserves_line_endings(self) -> None:
         with TemporaryDirectory() as workspace:
             test_file = Path(workspace) / "test.py"


@@ -1225,23 +1262,25 @@ class BlackTestCase(BlackBaseTestCase):
 
     def test_shhh_click(self) -> None:
         try:
 
     def test_shhh_click(self) -> None:
         try:

-            from click import _unicodefun
-        except ModuleNotFoundError:
+            from click import _unicodefun  # type: ignore
+        except ImportError:

             self.skipTest("Incompatible Click version")
             self.skipTest("Incompatible Click version")

-        if not hasattr(_unicodefun, "_verify_python3_env"):
+
+        if not hasattr(_unicodefun, "_verify_python_env"):

             self.skipTest("Incompatible Click version")
             self.skipTest("Incompatible Click version")

+

         # First, let's see if Click is crashing with a preferred ASCII charset.
         with patch("locale.getpreferredencoding") as gpe:
             gpe.return_value = "ASCII"
             with self.assertRaises(RuntimeError):
         # First, let's see if Click is crashing with a preferred ASCII charset.
         with patch("locale.getpreferredencoding") as gpe:
             gpe.return_value = "ASCII"
             with self.assertRaises(RuntimeError):

-                _unicodefun._verify_python3_env()  # type: ignore
+                _unicodefun._verify_python_env()

         # Now, let's silence Click...
         black.patch_click()
         # ...and confirm it's silent.
         with patch("locale.getpreferredencoding") as gpe:
             gpe.return_value = "ASCII"
             try:
         # Now, let's silence Click...
         black.patch_click()
         # ...and confirm it's silent.
         with patch("locale.getpreferredencoding") as gpe:
             gpe.return_value = "ASCII"
             try:

-                _unicodefun._verify_python3_env()  # type: ignore
+                _unicodefun._verify_python_env()

             except RuntimeError as re:
                 self.fail(f"`patch_click()` failed, exception still raised: {re}")
 
             except RuntimeError as re:
                 self.fail(f"`patch_click()` failed, exception still raised: {re}")
 


@@ -1279,6 +1318,7 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertEqual(config["color"], True)
         self.assertEqual(config["line_length"], 79)
         self.assertEqual(config["target_version"], ["py36", "py37", "py38"])
         self.assertEqual(config["color"], True)
         self.assertEqual(config["line_length"], 79)
         self.assertEqual(config["target_version"], ["py36", "py37", "py38"])

+        self.assertEqual(config["python_cell_magics"], ["custom1", "custom2"])

         self.assertEqual(config["exclude"], r"\.pyi?$")
         self.assertEqual(config["include"], r"\.py?$")
 
         self.assertEqual(config["exclude"], r"\.pyi?$")
         self.assertEqual(config["include"], r"\.py?$")
 


@@ -1296,6 +1336,7 @@ class BlackTestCase(BlackBaseTestCase):
         self.assertEqual(config["exclude"], r"\.pyi?$")
         self.assertEqual(config["include"], r"\.py?$")
 
         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)
     def test_find_project_root(self) -> None:
         with TemporaryDirectory() as workspace:
             root = Path(workspace)


@@ -1313,10 +1354,32 @@ class BlackTestCase(BlackBaseTestCase):
             src_python.touch()
 
             self.assertEqual(
             src_python.touch()
 
             self.assertEqual(

-                black.find_project_root((src_dir, test_dir)), root.resolve()
+                black.find_project_root((src_dir, test_dir)),
+                (root.resolve(), "pyproject.toml"),
+            )
+            self.assertEqual(
+                black.find_project_root((src_dir,)),
+                (src_dir.resolve(), "pyproject.toml"),
+            )
+            self.assertEqual(
+                black.find_project_root((src_python,)),
+                (src_dir.resolve(), "pyproject.toml"),

             )
             )

-            self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
-            self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
+
+    @patch(
+        "black.files.find_user_pyproject_toml",
+    )
+    def test_find_pyproject_toml(self, find_user_pyproject_toml: MagicMock) -> None:
+        find_user_pyproject_toml.side_effect = RuntimeError()
+
+        with redirect_stderr(io.StringIO()) as stderr:
+            result = black.files.find_pyproject_toml(
+                path_search_start=(str(Path.cwd().root),)
+            )
+
+        assert result is None
+        err = stderr.getvalue()
+        assert "Ignoring user configuration" in err

 
     @patch(
         "black.files.find_user_pyproject_toml",
 
     @patch(
         "black.files.find_user_pyproject_toml",


@@ -1363,6 +1426,25 @@ class BlackTestCase(BlackBaseTestCase):
             normalized_path = black.normalize_path_maybe_ignore(path, root, report)
             self.assertEqual(normalized_path, "workspace/project")
 
             normalized_path = black.normalize_path_maybe_ignore(path, root, report)
             self.assertEqual(normalized_path, "workspace/project")
 

+    def test_normalize_path_ignore_windows_junctions_outside_of_root(self) -> None:
+        if system() != "Windows":
+            return
+
+        with TemporaryDirectory() as workspace:
+            root = Path(workspace)
+            junction_dir = root / "junction"
+            junction_target_outside_of_root = root / ".."
+            os.system(f"mklink /J {junction_dir} {junction_target_outside_of_root}")
+
+            report = black.Report(verbose=True)
+            normalized_path = black.normalize_path_maybe_ignore(
+                junction_dir, root, report
+            )
+            # Manually delete for Python < 3.8
+            os.system(f"rmdir {junction_dir}")
+
+            self.assertEqual(normalized_path, None)
+

     def test_newline_comment_interaction(self) -> None:
         source = "class A:\\\r\n# type: ignore\n pass\n"
         output = black.format_str(source, mode=DEFAULT_MODE)
     def test_newline_comment_interaction(self) -> None:
         source = "class A:\\\r\n# type: ignore\n pass\n"
         output = black.format_str(source, mode=DEFAULT_MODE)


@@ -1390,27 +1472,6 @@ class BlackTestCase(BlackBaseTestCase):
         actual = diff_header.sub(DETERMINISTIC_HEADER, actual)
         self.assertEqual(actual, expected)
 
         actual = diff_header.sub(DETERMINISTIC_HEADER, actual)
         self.assertEqual(actual, expected)
 

-    @pytest.mark.python2
-    def test_docstring_reformat_for_py27(self) -> None:
-        """
-        Check that stripping trailing whitespace from Python 2 docstrings
-        doesn't trigger a "not equivalent to source" error
-        """
-        source = (
-            b'def foo():\r\n    """Testing\r\n    Testing """\r\n    print "Foo"\r\n'
-        )
-        expected = 'def foo():\n    """Testing\n    Testing"""\n    print "Foo"\n'
-
-        result = BlackRunner().invoke(
-            black.main,
-            ["-", "-q", "--target-version=py27"],
-            input=BytesIO(source),
-        )
-
-        self.assertEqual(result.exit_code, 0)
-        actual = result.stdout
-        self.assertFormatEqual(actual, expected)
-

     @staticmethod
     def compare_results(
         result: click.testing.Result, expected_value: str, expected_exit_code: int
     @staticmethod
     def compare_results(
         result: click.testing.Result, expected_value: str, expected_exit_code: int


@@ -1483,6 +1544,7 @@ class BlackTestCase(BlackBaseTestCase):
         assert output == result_diff, "The output did not match the expected value."
         assert result.exit_code == 0, "The exit code is incorrect."
 
         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
     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


@@ -1507,6 +1569,7 @@ class BlackTestCase(BlackBaseTestCase):
 
             self.compare_results(result, formatted, 0)
 
 
             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.
     def test_code_option_config(self) -> None:
         """
         Test that the code option finds the pyproject.toml in the current directory.


@@ -1527,6 +1590,7 @@ class BlackTestCase(BlackBaseTestCase):
                 call_args[0].lower() == str(pyproject_path).lower()
             ), "Incorrect config loaded."
 
                 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.
     def test_code_option_parent_config(self) -> None:
         """
         Test that the code option finds the pyproject.toml in the parent directory.


@@ -1546,8 +1610,54 @@ class BlackTestCase(BlackBaseTestCase):
                     call_args[0].lower() == str(pyproject_path).lower()
                 ), "Incorrect config loaded."
 
                     call_args[0].lower() == str(pyproject_path).lower()
                 ), "Incorrect config loaded."
 

+    def test_for_handled_unexpected_eof_error(self) -> None:
+        """
+        Test that an unexpected EOF SyntaxError is nicely presented.
+        """
+        with pytest.raises(black.parsing.InvalidInput) as exc_info:
+            black.lib2to3_parse("print(", {})
+
+        exc_info.match("Cannot parse: 2:0: EOF in multi-line statement")
+
+    def test_equivalency_ast_parse_failure_includes_error(self) -> None:
+        with pytest.raises(AssertionError) as err:
+            black.assert_equivalent("a«»a  = 1", "a«»a  = 1")
+
+        err.match("--safe")
+        # Unfortunately the SyntaxError message has changed in newer versions so we
+        # can't match it directly.
+        err.match("invalid character")
+        err.match(r"\(<unknown>, line 1\)")
+

 
 class TestCaching:
 
 class TestCaching:

+    def test_get_cache_dir(
+        self,
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        # Create multiple cache directories
+        workspace1 = tmp_path / "ws1"
+        workspace1.mkdir()
+        workspace2 = tmp_path / "ws2"
+        workspace2.mkdir()
+
+        # Force user_cache_dir to use the temporary directory for easier assertions
+        patch_user_cache_dir = patch(
+            target="black.cache.user_cache_dir",
+            autospec=True,
+            return_value=str(workspace1),
+        )
+
+        # If BLACK_CACHE_DIR is not set, use user_cache_dir
+        monkeypatch.delenv("BLACK_CACHE_DIR", raising=False)
+        with patch_user_cache_dir:
+            assert get_cache_dir() == workspace1
+
+        # If it is set, use the path provided in the env var.
+        monkeypatch.setenv("BLACK_CACHE_DIR", str(workspace2))
+        assert get_cache_dir() == workspace2
+

     def test_cache_broken_file(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace:
     def test_cache_broken_file(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace:


@@ -1573,7 +1683,7 @@ class TestCaching:
     def test_cache_multiple_files(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace, patch(
     def test_cache_multiple_files(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace, patch(

-            "black.ProcessPoolExecutor", new=ThreadPoolExecutor
+            "concurrent.futures.ProcessPoolExecutor", new=ThreadPoolExecutor

         ):
             one = (workspace / "one.py").resolve()
             with one.open("w") as fobj:
         ):
             one = (workspace / "one.py").resolve()
             with one.open("w") as fobj:


@@ -1682,7 +1792,7 @@ class TestCaching:
     def test_failed_formatting_does_not_get_cached(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace, patch(
     def test_failed_formatting_does_not_get_cached(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace, patch(

-            "black.ProcessPoolExecutor", new=ThreadPoolExecutor
+            "concurrent.futures.ProcessPoolExecutor", new=ThreadPoolExecutor

         ):
             failing = (workspace / "failing.py").resolve()
             with failing.open("w") as fobj:
         ):
             failing = (workspace / "failing.py").resolve()
             with failing.open("w") as fobj:


@@ -1718,6 +1828,7 @@ def assert_collected_sources(
     src: Sequence[Union[str, Path]],
     expected: Sequence[Union[str, Path]],
     *,
     src: Sequence[Union[str, Path]],
     expected: Sequence[Union[str, Path]],
     *,

+    ctx: Optional[FakeContext] = None,

     exclude: Optional[str] = None,
     include: Optional[str] = None,
     extend_exclude: Optional[str] = None,
     exclude: Optional[str] = None,
     include: Optional[str] = None,
     extend_exclude: Optional[str] = None,


@@ -1733,7 +1844,7 @@ def assert_collected_sources(
     )
     gs_force_exclude = None if force_exclude is None else compile_pattern(force_exclude)
     collected = black.get_sources(
     )
     gs_force_exclude = None if force_exclude is None else compile_pattern(force_exclude)
     collected = black.get_sources(

-        ctx=FakeContext(),
+        ctx=ctx or FakeContext(),

         src=gs_src,
         quiet=False,
         verbose=False,
         src=gs_src,
         quiet=False,
         verbose=False,


@@ -1744,7 +1855,7 @@ def assert_collected_sources(
         report=black.Report(),
         stdin_filename=stdin_filename,
     )
         report=black.Report(),
         stdin_filename=stdin_filename,
     )

-    assert sorted(list(collected)) == sorted(gs_expected)
+    assert sorted(collected) == sorted(gs_expected)

 
 
 class TestFileCollection:
 
 
 class TestFileCollection:


@@ -1769,9 +1880,11 @@ class TestFileCollection:
             base / "b/.definitely_exclude/a.pyi",
         ]
         src = [base / "b/"]
             base / "b/.definitely_exclude/a.pyi",
         ]
         src = [base / "b/"]

-        assert_collected_sources(src, expected, extend_exclude=r"/exclude/")
+        ctx = FakeContext()
+        ctx.obj["root"] = base
+        assert_collected_sources(src, expected, ctx=ctx, extend_exclude=r"/exclude/")

 
 

-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))

     def test_exclude_for_issue_1572(self) -> None:
         # Exclude shouldn't touch files that were explicitly given to Black through the
         # CLI. Exclude is supposed to only apply to the recursive discovery of files.
     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.


@@ -1894,6 +2007,7 @@ class TestFileCollection:
             src, expected, exclude=r"\.pyi$", extend_exclude=r"\.definitely_exclude"
         )
 
             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()
     def test_symlink_out_of_root_directory(self) -> None:
         path = MagicMock()
         root = THIS_DIR.resolve()


@@ -1907,7 +2021,6 @@ class TestFileCollection:
         path.iterdir.return_value = [child]
         child.resolve.return_value = Path("/a/b/c")
         child.as_posix.return_value = "/a/b/c"
         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(
         try:
             list(
                 black.gen_python_files(


@@ -1927,39 +2040,14 @@ class TestFileCollection:
             pytest.fail(f"`get_python_files_in_dir()` failed: {ve}")
         path.iterdir.assert_called_once()
         child.resolve.assert_called_once()
             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())
+
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))

     def test_get_sources_with_stdin(self) -> None:
         src = ["-"]
         expected = ["-"]
         assert_collected_sources(src, expected, include="", exclude=r"/exclude/|a\.py")
 
     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())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))

     def test_get_sources_with_stdin_filename(self) -> None:
         src = ["-"]
         stdin_filename = str(THIS_DIR / "data/collections.py")
     def test_get_sources_with_stdin_filename(self) -> None:
         src = ["-"]
         stdin_filename = str(THIS_DIR / "data/collections.py")


@@ -1971,7 +2059,7 @@ class TestFileCollection:
             stdin_filename=stdin_filename,
         )
 
             stdin_filename=stdin_filename,
         )
 

-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))

     def test_get_sources_with_stdin_filename_and_exclude(self) -> None:
         # Exclude shouldn't exclude stdin_filename since it is mimicking the
         # file being passed directly. This is the same as
     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


@@ -1987,7 +2075,7 @@ class TestFileCollection:
             stdin_filename=stdin_filename,
         )
 
             stdin_filename=stdin_filename,
         )
 

-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))

     def test_get_sources_with_stdin_filename_and_extend_exclude(self) -> None:
         # Extend exclude shouldn't exclude stdin_filename since it is mimicking the
         # file being passed directly. This is the same as
     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


@@ -2003,7 +2091,7 @@ class TestFileCollection:
             stdin_filename=stdin_filename,
         )
 
             stdin_filename=stdin_filename,
         )
 

-    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))

     def test_get_sources_with_stdin_filename_and_force_exclude(self) -> None:
         # Force exclude should exclude the file when passing it through
         # stdin_filename
     def test_get_sources_with_stdin_filename_and_force_exclude(self) -> None:
         # Force exclude should exclude the file when passing it through
         # stdin_filename


@@ -2017,38 +2105,12 @@ class TestFileCollection:
         )
 
 
         )
 
 

-@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
-
-
-with open(black.__file__, "r", encoding="utf-8") as _bf:
-    black_source_lines = _bf.readlines()
+try:
+    with open(black.__file__, "r", encoding="utf-8") as _bf:
+        black_source_lines = _bf.readlines()
+except UnicodeDecodeError:
+    if not black.COMPILED:
+        raise

 
 
 def tracefunc(
 
 
 def tracefunc(