Virtualenv is now formatted with newest Black https://github.com/pypa/virtualenv...

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

diff --git a/tests/test_black.py b/tests/test_black.py
index 3c766330a08c65608fb893246be674512e54352e..edcf7208b46aa685166dad061640cb8531c5717e 100644 (file)
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -1,16 +1,31 @@
 #!/usr/bin/env python3
 #!/usr/bin/env python3

+import multiprocessing

 import asyncio
 import logging
 from concurrent.futures import ThreadPoolExecutor
 from contextlib import contextmanager
 import asyncio
 import logging
 from concurrent.futures import ThreadPoolExecutor
 from contextlib import contextmanager

+from dataclasses import replace

 from functools import partial
 from functools import partial

+import inspect

 from io import BytesIO, TextIOWrapper
 import os
 from pathlib import Path
 from io import BytesIO, TextIOWrapper
 import os
 from pathlib import Path

+from platform import system

 import regex as re
 import sys
 from tempfile import TemporaryDirectory
 import regex as re
 import sys
 from tempfile import TemporaryDirectory

-from typing import Any, BinaryIO, Dict, Generator, List, Tuple, Iterator, TypeVar
+import types
+from typing import (
+    Any,
+    BinaryIO,
+    Callable,
+    Dict,
+    Generator,
+    List,
+    Tuple,
+    Iterator,
+    TypeVar,
+)

 import unittest
 from unittest.mock import patch, MagicMock
 
 import unittest
 from unittest.mock import patch, MagicMock
 


@@ -36,8 +51,9 @@ from pathspec import PathSpec
 from .test_primer import PrimerCLITests  # noqa: F401
 
 
 from .test_primer import PrimerCLITests  # noqa: F401
 
 

-ff = partial(black.format_file_in_place, mode=black.FileMode(), fast=True)
-fs = partial(black.format_str, mode=black.FileMode())
+DEFAULT_MODE = black.FileMode(experimental_string_processing=True)
+ff = partial(black.format_file_in_place, mode=DEFAULT_MODE, fast=True)
+fs = partial(black.format_str, mode=DEFAULT_MODE)

 THIS_FILE = Path(__file__)
 THIS_DIR = THIS_FILE.parent
 PROJECT_ROOT = THIS_DIR.parent
 THIS_FILE = Path(__file__)
 THIS_DIR = THIS_FILE.parent
 PROJECT_ROOT = THIS_DIR.parent


@@ -151,6 +167,7 @@ class BlackRunner(CliRunner):
 
 class BlackTestCase(unittest.TestCase):
     maxDiff = None
 
 class BlackTestCase(unittest.TestCase):
     maxDiff = None

+    _diffThreshold = 2 ** 20

 
     def assertFormatEqual(self, expected: str, actual: str) -> None:
         if actual != expected and not os.environ.get("SKIP_AST_PRINT"):
 
     def assertFormatEqual(self, expected: str, actual: str) -> None:
         if actual != expected and not os.environ.get("SKIP_AST_PRINT"):


@@ -169,7 +186,7 @@ class BlackTestCase(unittest.TestCase):
                 list(bdv.visit(exp_node))
             except Exception as ve:
                 black.err(str(ve))
                 list(bdv.visit(exp_node))
             except Exception as ve:
                 black.err(str(ve))

-        self.assertEqual(expected, actual)
+        self.assertMultiLineEqual(expected, actual)

 
     def invokeBlack(
         self, args: List[str], exit_code: int = 0, ignore_config: bool = True
 
     def invokeBlack(
         self, args: List[str], exit_code: int = 0, ignore_config: bool = True


@@ -190,13 +207,13 @@ class BlackTestCase(unittest.TestCase):
         )
 
     @patch("black.dump_to_file", dump_to_stderr)
         )
 
     @patch("black.dump_to_file", dump_to_stderr)

-    def checkSourceFile(self, name: str) -> None:
+    def checkSourceFile(self, name: str, mode: black.FileMode = DEFAULT_MODE) -> None:

         path = THIS_DIR.parent / name
         source, expected = read_data(str(path), data=False)
         path = THIS_DIR.parent / name
         source, expected = read_data(str(path), data=False)

-        actual = fs(source)
+        actual = fs(source, mode=mode)

         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, mode)

         self.assertFalse(ff(path))
 
     @patch("black.dump_to_file", dump_to_stderr)
         self.assertFalse(ff(path))
 
     @patch("black.dump_to_file", dump_to_stderr)


@@ -205,7 +222,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     def test_empty_ff(self) -> None:
         expected = ""
 
     def test_empty_ff(self) -> None:
         expected = ""


@@ -267,7 +284,7 @@ class BlackTestCase(unittest.TestCase):
         self.assertEqual(result.exit_code, 0)
         self.assertFormatEqual(expected, result.output)
         black.assert_equivalent(source, result.output)
         self.assertEqual(result.exit_code, 0)
         self.assertFormatEqual(expected, result.output)
         black.assert_equivalent(source, result.output)

-        black.assert_stable(source, result.output, black.FileMode())
+        black.assert_stable(source, result.output, DEFAULT_MODE)

 
     def test_piping_diff(self) -> None:
         diff_header = re.compile(
 
     def test_piping_diff(self) -> None:
         diff_header = re.compile(


@@ -320,7 +337,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_function2(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_function2(self) -> None:


@@ -328,6 +345,21 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

+        black.assert_stable(source, actual, DEFAULT_MODE)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def _test_wip(self) -> None:
+        source, expected = read_data("wip")
+        sys.settrace(tracefunc)
+        mode = replace(
+            DEFAULT_MODE,
+            experimental_string_processing=False,
+            target_versions={black.TargetVersion.PY38},
+        )
+        actual = fs(source, mode=mode)
+        sys.settrace(None)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)

         black.assert_stable(source, actual, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)
         black.assert_stable(source, actual, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)


@@ -336,7 +368,28 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)
+
+    @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_expression(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_expression(self) -> None:


@@ -344,14 +397,14 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        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)
 
     @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, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

         if sys.version_info >= (3, 8):
             black.assert_equivalent(source, actual)
 
         if sys.version_info >= (3, 8):
             black.assert_equivalent(source, actual)
 


@@ -375,7 +428,7 @@ class BlackTestCase(unittest.TestCase):
         self.assertFormatEqual(expected, actual)
         with patch("black.dump_to_file", dump_to_stderr):
             black.assert_equivalent(source, actual)
         self.assertFormatEqual(expected, actual)
         with patch("black.dump_to_file", dump_to_stderr):
             black.assert_equivalent(source, actual)

-            black.assert_stable(source, actual, black.FileMode())
+            black.assert_stable(source, actual, DEFAULT_MODE)

 
     def test_expression_diff(self) -> None:
         source, _ = read_data("expression.py")
 
     def test_expression_diff(self) -> None:
         source, _ = read_data("expression.py")


@@ -427,14 +480,14 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @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)
 
     @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, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

         if sys.version_info >= (3, 8):
             black.assert_equivalent(source, actual)
 
         if sys.version_info >= (3, 8):
             black.assert_equivalent(source, actual)
 


@@ -452,8 +505,8 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
-        mode = black.FileMode(string_normalization=False)
+        black.assert_stable(source, actual, DEFAULT_MODE)
+        mode = replace(DEFAULT_MODE, string_normalization=False)

         not_normalized = fs(source, mode=mode)
         self.assertFormatEqual(source.replace("\\\n", ""), not_normalized)
         black.assert_equivalent(source, not_normalized)
         not_normalized = fs(source, mode=mode)
         self.assertFormatEqual(source.replace("\\\n", ""), not_normalized)
         black.assert_equivalent(source, not_normalized)


@@ -465,7 +518,17 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_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(self) -> None:
         """Tests for splitting long strings."""
 
     def test_long_strings(self) -> None:
         """Tests for splitting long strings."""


@@ -473,7 +536,15 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_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_long_strings__edge_case(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_long_strings__edge_case(self) -> None:


@@ -482,7 +553,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_long_strings__regression(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_long_strings__regression(self) -> None:


@@ -491,7 +562,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_slices(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_slices(self) -> None:


@@ -499,7 +570,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_percent_precedence(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_percent_precedence(self) -> None:


@@ -507,7 +578,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments(self) -> None:


@@ -515,7 +586,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments2(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments2(self) -> None:


@@ -523,7 +594,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments3(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments3(self) -> None:


@@ -531,7 +602,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments4(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments4(self) -> None:


@@ -539,7 +610,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments5(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments5(self) -> None:


@@ -547,7 +618,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments6(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments6(self) -> None:


@@ -555,15 +626,16 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments7(self) -> None:
         source, expected = read_data("comments7")
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments7(self) -> None:
         source, expected = read_data("comments7")

-        actual = fs(source)
+        mode = replace(DEFAULT_MODE, target_versions={black.TargetVersion.PY38})
+        actual = fs(source, mode=mode)

         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comment_after_escaped_newline(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comment_after_escaped_newline(self) -> None:


@@ -571,7 +643,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_cantfit(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_cantfit(self) -> None:


@@ -579,7 +651,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_import_spacing(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_import_spacing(self) -> None:


@@ -587,7 +659,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_composition(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_composition(self) -> None:


@@ -595,7 +667,16 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_composition_no_trailing_comma(self) -> None:
+        source, expected = read_data("composition_no_trailing_comma")
+        mode = replace(DEFAULT_MODE, target_versions={black.TargetVersion.PY38})
+        actual = fs(source, mode=mode)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_empty_lines(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_empty_lines(self) -> None:


@@ -603,7 +684,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_remove_parens(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_remove_parens(self) -> None:


@@ -611,7 +692,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_string_prefixes(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_string_prefixes(self) -> None:


@@ -619,12 +700,12 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_numeric_literals(self) -> None:
         source, expected = read_data("numeric_literals")
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_numeric_literals(self) -> None:
         source, expected = read_data("numeric_literals")

-        mode = black.FileMode(target_versions=black.PY36_VERSIONS)
+        mode = replace(DEFAULT_MODE, target_versions=black.PY36_VERSIONS)

         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -633,7 +714,7 @@ class BlackTestCase(unittest.TestCase):
     @patch("black.dump_to_file", dump_to_stderr)
     def test_numeric_literals_ignoring_underscores(self) -> None:
         source, expected = read_data("numeric_literals_skip_underscores")
     @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 = black.FileMode(target_versions=black.PY36_VERSIONS)
+        mode = replace(DEFAULT_MODE, target_versions=black.PY36_VERSIONS)

         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -644,7 +725,7 @@ class BlackTestCase(unittest.TestCase):
         source, expected = read_data("numeric_literals_py2")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         source, expected = read_data("numeric_literals_py2")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2(self) -> None:


@@ -652,12 +733,12 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2_print_function(self) -> None:
         source, expected = read_data("python2_print_function")
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2_print_function(self) -> None:
         source, expected = read_data("python2_print_function")

-        mode = black.FileMode(target_versions={TargetVersion.PY27})
+        mode = replace(DEFAULT_MODE, target_versions={TargetVersion.PY27})

         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -669,11 +750,11 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_stub(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_stub(self) -> None:

-        mode = black.FileMode(is_pyi=True)
+        mode = replace(DEFAULT_MODE, is_pyi=True)

         source, expected = read_data("stub.pyi")
         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         source, expected = read_data("stub.pyi")
         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)


@@ -688,7 +769,7 @@ class BlackTestCase(unittest.TestCase):
         major, minor = sys.version_info[:2]
         if major < 3 or (major <= 3 and minor < 7):
             black.assert_equivalent(source, actual)
         major, minor = sys.version_info[:2]
         if major < 3 or (major <= 3 and minor < 7):
             black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

         # ensure black can parse this when the target is 3.6
         self.invokeBlack([str(source_path), "--target-version", "py36"])
         # but not on 3.7, because async/await is no longer an identifier
         # ensure black can parse this when the target is 3.6
         self.invokeBlack([str(source_path), "--target-version", "py36"])
         # but not on 3.7, because async/await is no longer an identifier


@@ -703,7 +784,7 @@ class BlackTestCase(unittest.TestCase):
         major, minor = sys.version_info[:2]
         if major > 3 or (major == 3 and minor >= 7):
             black.assert_equivalent(source, actual)
         major, minor = sys.version_info[:2]
         if major > 3 or (major == 3 and minor >= 7):
             black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

         # ensure black can parse this when the target is 3.7
         self.invokeBlack([str(source_path), "--target-version", "py37"])
         # but not on 3.6, because we use async as a reserved keyword
         # ensure black can parse this when the target is 3.7
         self.invokeBlack([str(source_path), "--target-version", "py37"])
         # but not on 3.6, because we use async as a reserved keyword


@@ -717,7 +798,7 @@ class BlackTestCase(unittest.TestCase):
         major, minor = sys.version_info[:2]
         if major > 3 or (major == 3 and minor >= 8):
             black.assert_equivalent(source, 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, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff(self) -> None:


@@ -725,7 +806,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff2(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff2(self) -> None:


@@ -733,7 +814,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff3(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff3(self) -> None:


@@ -741,7 +822,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff4(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff4(self) -> None:


@@ -749,7 +830,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_remove_empty_parentheses_after_class(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_remove_empty_parentheses_after_class(self) -> None:


@@ -757,7 +838,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_new_line_between_class_and_code(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_new_line_between_class_and_code(self) -> None:


@@ -765,7 +846,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_bracket_match(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_bracket_match(self) -> None:


@@ -773,7 +854,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_tuple_assign(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_tuple_assign(self) -> None:


@@ -781,7 +862,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_beginning_backslash(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_beginning_backslash(self) -> None:


@@ -789,7 +870,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        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"
 
     def test_tab_comment_indentation(self) -> None:
         contents_tab = "if 1:\n\tif 2:\n\t\tpass\n\t# comment\n\tpass\n"


@@ -1218,7 +1299,7 @@ class BlackTestCase(unittest.TestCase):
 
     def test_format_file_contents(self) -> None:
         empty = ""
 
     def test_format_file_contents(self) -> None:
         empty = ""

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with self.assertRaises(black.NothingChanged):
             black.format_file_contents(empty, mode=mode, fast=False)
         just_nl = "\n"
         with self.assertRaises(black.NothingChanged):
             black.format_file_contents(empty, mode=mode, fast=False)
         just_nl = "\n"


@@ -1263,7 +1344,7 @@ class BlackTestCase(unittest.TestCase):
         self.assertEqual("".join(err_lines), "")
 
     def test_cache_broken_file(self) -> None:
         self.assertEqual("".join(err_lines), "")
 
     def test_cache_broken_file(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir() as workspace:
             cache_file = black.get_cache_file(mode)
             with cache_file.open("w") as fobj:
         with cache_dir() as workspace:
             cache_file = black.get_cache_file(mode)
             with cache_file.open("w") as fobj:


@@ -1277,7 +1358,7 @@ class BlackTestCase(unittest.TestCase):
             self.assertIn(src, cache)
 
     def test_cache_single_file_already_cached(self) -> None:
             self.assertIn(src, cache)
 
     def test_cache_single_file_already_cached(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             with src.open("w") as fobj:
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             with src.open("w") as fobj:


@@ -1289,7 +1370,7 @@ class BlackTestCase(unittest.TestCase):
 
     @event_loop()
     def test_cache_multiple_files(self) -> None:
 
     @event_loop()
     def test_cache_multiple_files(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir() as workspace, patch(
             "black.ProcessPoolExecutor", new=ThreadPoolExecutor
         ):
         with cache_dir() as workspace, patch(
             "black.ProcessPoolExecutor", new=ThreadPoolExecutor
         ):


@@ -1310,17 +1391,63 @@ class BlackTestCase(unittest.TestCase):
             self.assertIn(two, cache)
 
     def test_no_cache_when_writeback_diff(self) -> None:
             self.assertIn(two, cache)
 
     def test_no_cache_when_writeback_diff(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             with src.open("w") as fobj:
                 fobj.write("print('hello')")
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             with src.open("w") as fobj:
                 fobj.write("print('hello')")

-            self.invokeBlack([str(src), "--diff"])
-            cache_file = black.get_cache_file(mode)
-            self.assertFalse(cache_file.exists())
+            with patch("black.read_cache") as read_cache, patch(
+                "black.write_cache"
+            ) as write_cache:
+                self.invokeBlack([str(src), "--diff"])
+                cache_file = black.get_cache_file(mode)
+                self.assertFalse(cache_file.exists())
+                write_cache.assert_not_called()
+                read_cache.assert_not_called()
+
+    def test_no_cache_when_writeback_color_diff(self) -> None:
+        mode = DEFAULT_MODE
+        with cache_dir() as workspace:
+            src = (workspace / "test.py").resolve()
+            with src.open("w") as fobj:
+                fobj.write("print('hello')")
+            with patch("black.read_cache") as read_cache, patch(
+                "black.write_cache"
+            ) as write_cache:
+                self.invokeBlack([str(src), "--diff", "--color"])
+                cache_file = black.get_cache_file(mode)
+                self.assertFalse(cache_file.exists())
+                write_cache.assert_not_called()
+                read_cache.assert_not_called()
+
+    @event_loop()
+    def test_output_locking_when_writeback_diff(self) -> None:
+        with cache_dir() as workspace:
+            for tag in range(0, 4):
+                src = (workspace / f"test{tag}.py").resolve()
+                with src.open("w") as fobj:
+                    fobj.write("print('hello')")
+            with patch("black.Manager", wraps=multiprocessing.Manager) as mgr:
+                self.invokeBlack(["--diff", str(workspace)], exit_code=0)
+                # this isn't quite doing what we want, but if it _isn't_
+                # called then we cannot be using the lock it provides
+                mgr.assert_called()
+
+    @event_loop()
+    def test_output_locking_when_writeback_color_diff(self) -> None:
+        with cache_dir() as workspace:
+            for tag in range(0, 4):
+                src = (workspace / f"test{tag}.py").resolve()
+                with src.open("w") as fobj:
+                    fobj.write("print('hello')")
+            with patch("black.Manager", wraps=multiprocessing.Manager) as mgr:
+                self.invokeBlack(["--diff", "--color", str(workspace)], exit_code=0)
+                # this isn't quite doing what we want, but if it _isn't_
+                # called then we cannot be using the lock it provides
+                mgr.assert_called()

 
     def test_no_cache_when_stdin(self) -> None:
 
     def test_no_cache_when_stdin(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir():
             result = CliRunner().invoke(
                 black.main, ["-"], input=BytesIO(b"print('hello')")
         with cache_dir():
             result = CliRunner().invoke(
                 black.main, ["-"], input=BytesIO(b"print('hello')")


@@ -1330,12 +1457,12 @@ class BlackTestCase(unittest.TestCase):
             self.assertFalse(cache_file.exists())
 
     def test_read_cache_no_cachefile(self) -> None:
             self.assertFalse(cache_file.exists())
 
     def test_read_cache_no_cachefile(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir():
             self.assertEqual(black.read_cache(mode), {})
 
     def test_write_cache_read_cache(self) -> None:
         with cache_dir():
             self.assertEqual(black.read_cache(mode), {})
 
     def test_write_cache_read_cache(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.touch()
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.touch()


@@ -1361,7 +1488,7 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(done, {cached})
 
     def test_write_cache_creates_directory_if_needed(self) -> None:
             self.assertEqual(done, {cached})
 
     def test_write_cache_creates_directory_if_needed(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir(exists=False) as workspace:
             self.assertFalse(workspace.exists())
             black.write_cache({}, [], mode)
         with cache_dir(exists=False) as workspace:
             self.assertFalse(workspace.exists())
             black.write_cache({}, [], mode)


@@ -1369,7 +1496,7 @@ class BlackTestCase(unittest.TestCase):
 
     @event_loop()
     def test_failed_formatting_does_not_get_cached(self) -> None:
 
     @event_loop()
     def test_failed_formatting_does_not_get_cached(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir() as workspace, patch(
             "black.ProcessPoolExecutor", new=ThreadPoolExecutor
         ):
         with cache_dir() as workspace, patch(
             "black.ProcessPoolExecutor", new=ThreadPoolExecutor
         ):


@@ -1385,7 +1512,7 @@ class BlackTestCase(unittest.TestCase):
             self.assertIn(clean, cache)
 
     def test_write_cache_write_fail(self) -> None:
             self.assertIn(clean, cache)
 
     def test_write_cache_write_fail(self) -> None:

-        mode = black.FileMode()
+        mode = DEFAULT_MODE

         with cache_dir(), patch.object(Path, "open") as mock:
             mock.side_effect = OSError
             black.write_cache({}, [], mode)
         with cache_dir(), patch.object(Path, "open") as mock:
             mock.side_effect = OSError
             black.write_cache({}, [], mode)


@@ -1428,8 +1555,8 @@ class BlackTestCase(unittest.TestCase):
             self.invokeBlack([str(workspace.resolve())])
 
     def test_read_cache_line_lengths(self) -> None:
             self.invokeBlack([str(workspace.resolve())])
 
     def test_read_cache_line_lengths(self) -> None:

-        mode = black.FileMode()
-        short_mode = black.FileMode(line_length=1)
+        mode = DEFAULT_MODE
+        short_mode = replace(DEFAULT_MODE, line_length=1)

         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()
             path.touch()
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()
             path.touch()


@@ -1444,11 +1571,11 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     def test_single_file_force_pyi(self) -> None:
 
     def test_single_file_force_pyi(self) -> None:

-        reg_mode = black.FileMode()
-        pyi_mode = black.FileMode(is_pyi=True)
+        reg_mode = DEFAULT_MODE
+        pyi_mode = replace(DEFAULT_MODE, is_pyi=True)

         contents, expected = read_data("force_pyi")
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()
         contents, expected = read_data("force_pyi")
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()


@@ -1466,8 +1593,8 @@ class BlackTestCase(unittest.TestCase):
 
     @event_loop()
     def test_multi_file_force_pyi(self) -> None:
 
     @event_loop()
     def test_multi_file_force_pyi(self) -> None:

-        reg_mode = black.FileMode()
-        pyi_mode = black.FileMode(is_pyi=True)
+        reg_mode = DEFAULT_MODE
+        pyi_mode = replace(DEFAULT_MODE, is_pyi=True)

         contents, expected = read_data("force_pyi")
         with cache_dir() as workspace:
             paths = [
         contents, expected = read_data("force_pyi")
         with cache_dir() as workspace:
             paths = [


@@ -1499,8 +1626,8 @@ class BlackTestCase(unittest.TestCase):
         self.assertFormatEqual(actual, expected)
 
     def test_single_file_force_py36(self) -> None:
         self.assertFormatEqual(actual, expected)
 
     def test_single_file_force_py36(self) -> None:

-        reg_mode = black.FileMode()
-        py36_mode = black.FileMode(target_versions=black.PY36_VERSIONS)
+        reg_mode = DEFAULT_MODE
+        py36_mode = replace(DEFAULT_MODE, target_versions=black.PY36_VERSIONS)

         source, expected = read_data("force_py36")
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()
         source, expected = read_data("force_py36")
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()


@@ -1518,8 +1645,8 @@ class BlackTestCase(unittest.TestCase):
 
     @event_loop()
     def test_multi_file_force_py36(self) -> None:
 
     @event_loop()
     def test_multi_file_force_py36(self) -> None:

-        reg_mode = black.FileMode()
-        py36_mode = black.FileMode(target_versions=black.PY36_VERSIONS)
+        reg_mode = DEFAULT_MODE
+        py36_mode = replace(DEFAULT_MODE, target_versions=black.PY36_VERSIONS)

         source, expected = read_data("force_py36")
         with cache_dir() as workspace:
             paths = [
         source, expected = read_data("force_py36")
         with cache_dir() as workspace:
             paths = [


@@ -1546,7 +1673,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, black.FileMode())
+        black.assert_stable(source, actual, DEFAULT_MODE)

 
     def test_pipe_force_py36(self) -> None:
         source, expected = read_data("force_py36")
 
     def test_pipe_force_py36(self) -> None:
         source, expected = read_data("force_py36")


@@ -1827,9 +1954,7 @@ class BlackTestCase(unittest.TestCase):
     def test_read_pyproject_toml(self) -> None:
         test_toml_file = THIS_DIR / "test.toml"
         fake_ctx = FakeContext()
     def test_read_pyproject_toml(self) -> None:
         test_toml_file = THIS_DIR / "test.toml"
         fake_ctx = FakeContext()

-        black.read_pyproject_toml(
-            fake_ctx, FakeParameter(), str(test_toml_file),
-        )
+        black.read_pyproject_toml(fake_ctx, FakeParameter(), str(test_toml_file))

         config = fake_ctx.default_map
         self.assertEqual(config["verbose"], "1")
         self.assertEqual(config["check"], "no")
         config = fake_ctx.default_map
         self.assertEqual(config["verbose"], "1")
         self.assertEqual(config["check"], "no")


@@ -1862,6 +1987,23 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
             self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
 
             self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
             self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
 

+    def test_bpo_33660_workaround(self) -> None:
+        if system() == "Windows":
+            return
+
+        # https://bugs.python.org/issue33660
+
+        old_cwd = Path.cwd()
+        try:
+            root = Path("/")
+            os.chdir(str(root))
+            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))
+

 
 class BlackDTestCase(AioHTTPTestCase):
     async def get_application(self) -> web.Application:
 
 class BlackDTestCase(AioHTTPTestCase):
     async def get_application(self) -> web.Application:


@@ -2031,5 +2173,31 @@ class BlackDTestCase(AioHTTPTestCase):
         self.assertIsNotNone(response.headers.get(blackd.BLACK_VERSION_HEADER))
 
 
         self.assertIsNotNone(response.headers.get(blackd.BLACK_VERSION_HEADER))
 
 

+with open(black.__file__, "r", encoding="utf-8") as _bf:
+    black_source_lines = _bf.readlines()
+
+
+def tracefunc(frame: types.FrameType, event: str, arg: Any) -> Callable:
+    """Show function calls `from black/__init__.py` as they happen.
+
+    Register this with `sys.settrace()` in a test you're debugging.
+    """
+    if event != "call":
+        return tracefunc
+
+    stack = len(inspect.stack()) - 19
+    stack *= 2
+    filename = frame.f_code.co_filename
+    lineno = frame.f_lineno
+    func_sig_lineno = lineno - 1
+    funcname = black_source_lines[func_sig_lineno].strip()
+    while funcname.startswith("@"):
+        func_sig_lineno += 1
+        funcname = black_source_lines[func_sig_lineno].strip()
+    if "black/__init__.py" in filename:
+        print(f"{' ' * stack}{lineno}:{funcname}")
+    return tracefunc
+
+

 if __name__ == "__main__":
     unittest.main(module="test_black")
 if __name__ == "__main__":
     unittest.main(module="test_black")