Remove flake8 W503 from docs as it is ignored by default (#1661)

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

diff --git a/tests/test_black.py b/tests/test_black.py
index ce8403757f1d699b890dd3c65759fc5b833223ba..bc80c8fca8b20c8f67b4384d722be1a84764b762 100644 (file)
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -3,17 +3,32 @@ import asyncio
 import logging
 from concurrent.futures import ThreadPoolExecutor
 from contextlib import contextmanager
 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

-import re
+from platform import system
+import regex as re

 import sys
 from tempfile import TemporaryDirectory
 import sys
 from tempfile import TemporaryDirectory

-from typing import Any, BinaryIO, 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
 

+import click

 from click import unstyle
 from click.testing import CliRunner
 
 from click import unstyle
 from click.testing import CliRunner
 


@@ -29,10 +44,19 @@ except ImportError:
 else:
     has_blackd_deps = True
 
 else:
     has_blackd_deps = True
 

-ff = partial(black.format_file_in_place, mode=black.FileMode(), fast=True)
-fs = partial(black.format_str, mode=black.FileMode())
+from pathspec import PathSpec
+
+# Import other test classes
+from .test_primer import PrimerCLITests  # noqa: F401
+
+
+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
 THIS_FILE = Path(__file__)
 THIS_DIR = THIS_FILE.parent

+PROJECT_ROOT = THIS_DIR.parent
+DETERMINISTIC_HEADER = "[Deterministic header]"

 EMPTY_LINE = "# EMPTY LINE WITH WHITESPACE" + " (this comment will be removed)"
 PY36_ARGS = [
     f"--target-version={version.name.lower()}" for version in black.PY36_VERSIONS
 EMPTY_LINE = "# EMPTY LINE WITH WHITESPACE" + " (this comment will be removed)"
 PY36_ARGS = [
     f"--target-version={version.name.lower()}" for version in black.PY36_VERSIONS


@@ -51,7 +75,7 @@ def read_data(name: str, data: bool = True) -> Tuple[str, str]:
         name += ".py"
     _input: List[str] = []
     _output: List[str] = []
         name += ".py"
     _input: List[str] = []
     _output: List[str] = []

-    base_dir = THIS_DIR / "data" if data else THIS_DIR
+    base_dir = THIS_DIR / "data" if data else PROJECT_ROOT

     with open(base_dir / name, "r", encoding="utf8") as test:
         lines = test.readlines()
     result = _input
     with open(base_dir / name, "r", encoding="utf8") as test:
         lines = test.readlines()
     result = _input


@@ -79,7 +103,7 @@ def cache_dir(exists: bool = True) -> Iterator[Path]:
 
 
 @contextmanager
 
 
 @contextmanager

-def event_loop(close: bool) -> Iterator[None]:
+def event_loop() -> Iterator[None]:

     policy = asyncio.get_event_loop_policy()
     loop = policy.new_event_loop()
     asyncio.set_event_loop(loop)
     policy = asyncio.get_event_loop_policy()
     loop = policy.new_event_loop()
     asyncio.set_event_loop(loop)


@@ -87,8 +111,7 @@ def event_loop(close: bool) -> Iterator[None]:
         yield
 
     finally:
         yield
 
     finally:

-        if close:
-            loop.close()
+        loop.close()

 
 
 @contextmanager
 
 
 @contextmanager


@@ -102,6 +125,20 @@ def skip_if_exception(e: str) -> Iterator[None]:
             raise
 
 
             raise
 
 

+class FakeContext(click.Context):
+    """A fake click Context for when calling functions that need it."""
+
+    def __init__(self) -> None:
+        self.default_map: Dict[str, Any] = {}
+
+
+class FakeParameter(click.Parameter):
+    """A fake click Parameter for when calling functions that need it."""
+
+    def __init__(self) -> None:
+        pass
+
+

 class BlackRunner(CliRunner):
     """Modify CliRunner so that stderr is not merged with stdout.
 
 class BlackRunner(CliRunner):
     """Modify CliRunner so that stderr is not merged with stdout.
 


@@ -129,6 +166,7 @@ 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"):


@@ -147,16 +185,35 @@ 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
     ) -> None:
         runner = BlackRunner()
         if ignore_config:
 
     def invokeBlack(
         self, args: List[str], exit_code: int = 0, ignore_config: bool = True
     ) -> None:
         runner = BlackRunner()
         if ignore_config:

-            args = ["--config", str(THIS_DIR / "empty.toml"), *args]
+            args = ["--verbose", "--config", str(THIS_DIR / "empty.toml"), *args]

         result = runner.invoke(black.main, args)
         result = runner.invoke(black.main, args)

-        self.assertEqual(result.exit_code, exit_code, msg=runner.stderr_bytes.decode())
+        self.assertEqual(
+            result.exit_code,
+            exit_code,
+            msg=(
+                f"Failed with args: {args}\n"
+                f"stdout: {runner.stdout_bytes.decode()!r}\n"
+                f"stderr: {runner.stderr_bytes.decode()!r}\n"
+                f"exception: {result.exception}"
+            ),
+        )
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def checkSourceFile(self, name: str, mode: black.FileMode = DEFAULT_MODE) -> None:
+        path = THIS_DIR.parent / name
+        source, expected = read_data(str(path), data=False)
+        actual = fs(source, mode=mode)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, mode)
+        self.assertFalse(ff(path))

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


@@ -164,7 +221,7 @@ 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 = ""


@@ -177,26 +234,47 @@ class BlackTestCase(unittest.TestCase):
             os.unlink(tmp_file)
         self.assertFormatEqual(expected, actual)
 
             os.unlink(tmp_file)
         self.assertFormatEqual(expected, actual)
 

-    @patch("black.dump_to_file", dump_to_stderr)

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

-        source, expected = read_data("test_black", data=False)
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, black.FileMode())
-        self.assertFalse(ff(THIS_FILE))
+        self.checkSourceFile("tests/test_black.py")

 
 

-    @patch("black.dump_to_file", dump_to_stderr)

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

-        source, expected = read_data("../black", data=False)
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, black.FileMode())
-        self.assertFalse(ff(THIS_DIR / ".." / "black.py"))
+        self.checkSourceFile("src/black/__init__.py")
+
+    def test_pygram(self) -> None:
+        self.checkSourceFile("src/blib2to3/pygram.py")
+
+    def test_pytree(self) -> None:
+        self.checkSourceFile("src/blib2to3/pytree.py")
+
+    def test_conv(self) -> None:
+        self.checkSourceFile("src/blib2to3/pgen2/conv.py")
+
+    def test_driver(self) -> None:
+        self.checkSourceFile("src/blib2to3/pgen2/driver.py")
+
+    def test_grammar(self) -> None:
+        self.checkSourceFile("src/blib2to3/pgen2/grammar.py")
+
+    def test_literals(self) -> None:
+        self.checkSourceFile("src/blib2to3/pgen2/literals.py")
+
+    def test_parse(self) -> None:
+        self.checkSourceFile("src/blib2to3/pgen2/parse.py")
+
+    def test_pgen(self) -> None:
+        self.checkSourceFile("src/blib2to3/pgen2/pgen.py")
+
+    def test_tokenize(self) -> None:
+        self.checkSourceFile("src/blib2to3/pgen2/tokenize.py")
+
+    def test_token(self) -> None:
+        self.checkSourceFile("src/blib2to3/pgen2/token.py")
+
+    def test_setup(self) -> None:
+        self.checkSourceFile("setup.py")

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

-        source, expected = read_data("../black", data=False)
+        source, expected = read_data("src/black/__init__", data=False)

         result = BlackRunner().invoke(
             black.main,
             ["-", "--fast", f"--line-length={black.DEFAULT_LINE_LENGTH}"],
         result = BlackRunner().invoke(
             black.main,
             ["-", "--fast", f"--line-length={black.DEFAULT_LINE_LENGTH}"],


@@ -205,12 +283,12 @@ 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(

-            rf"(STDIN|STDOUT)\t\d\d\d\d-\d\d-\d\d "
-            rf"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
+            r"(STDIN|STDOUT)\t\d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d\.\d\d\d\d\d\d "
+            r"\+\d\d\d\d"

         )
         source, _ = read_data("expression.py")
         expected, _ = read_data("expression.diff")
         )
         source, _ = read_data("expression.py")
         expected, _ = read_data("expression.diff")


@@ -226,18 +304,31 @@ class BlackTestCase(unittest.TestCase):
             black.main, args, input=BytesIO(source.encode("utf8"))
         )
         self.assertEqual(result.exit_code, 0)
             black.main, args, input=BytesIO(source.encode("utf8"))
         )
         self.assertEqual(result.exit_code, 0)

-        actual = diff_header.sub("[Deterministic header]", result.output)
+        actual = diff_header.sub(DETERMINISTIC_HEADER, result.output)

         actual = actual.rstrip() + "\n"  # the diff output has a trailing space
         self.assertEqual(expected, actual)
 
         actual = actual.rstrip() + "\n"  # the diff output has a trailing space
         self.assertEqual(expected, actual)
 

-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_setup(self) -> None:
-        source, expected = read_data("../setup", data=False)
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, black.FileMode())
-        self.assertFalse(ff(THIS_DIR / ".." / "setup.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",
+            f"--config={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.
+        self.assertIn("\033[1;37m", actual)
+        self.assertIn("\033[36m", actual)
+        self.assertIn("\033[32m", actual)
+        self.assertIn("\033[31m", actual)
+        self.assertIn("\033[0m", actual)

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


@@ -245,7 +336,7 @@ 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:


@@ -253,6 +344,21 @@ 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)


@@ -261,7 +367,28 @@ 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:


@@ -269,14 +396,14 @@ 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)
 


@@ -300,7 +427,7 @@ 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")


@@ -308,7 +435,7 @@ class BlackTestCase(unittest.TestCase):
         tmp_file = Path(black.dump_to_file(source))
         diff_header = re.compile(
             rf"{re.escape(str(tmp_file))}\t\d\d\d\d-\d\d-\d\d "
         tmp_file = Path(black.dump_to_file(source))
         diff_header = re.compile(
             rf"{re.escape(str(tmp_file))}\t\d\d\d\d-\d\d-\d\d "

-            rf"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
+            r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"

         )
         try:
             result = BlackRunner().invoke(black.main, ["--diff", str(tmp_file)])
         )
         try:
             result = BlackRunner().invoke(black.main, ["--diff", str(tmp_file)])


@@ -316,31 +443,50 @@ class BlackTestCase(unittest.TestCase):
         finally:
             os.unlink(tmp_file)
         actual = result.output
         finally:
             os.unlink(tmp_file)
         actual = result.output

-        actual = diff_header.sub("[Deterministic header]", actual)
+        actual = diff_header.sub(DETERMINISTIC_HEADER, actual)

         actual = actual.rstrip() + "\n"  # the diff output has a trailing space
         if expected != actual:
             dump = black.dump_to_file(actual)
             msg = (
         actual = actual.rstrip() + "\n"  # the diff output has a trailing space
         if expected != actual:
             dump = black.dump_to_file(actual)
             msg = (

-                f"Expected diff isn't equal to the actual. If you made changes "
-                f"to expression.py and this is an anticipated difference, "
-                f"overwrite tests/data/expression.diff with {dump}"
+                "Expected diff isn't equal to the actual. If you made changes to"
+                " expression.py and this is an anticipated difference, overwrite"
+                f" tests/data/expression.diff with {dump}"

             )
             self.assertEqual(expected, actual, msg)
 
             )
             self.assertEqual(expected, actual, msg)
 

+    def test_expression_diff_with_color(self) -> None:
+        source, _ = read_data("expression.py")
+        expected, _ = read_data("expression.diff")
+        tmp_file = Path(black.dump_to_file(source))
+        try:
+            result = BlackRunner().invoke(
+                black.main, ["--diff", "--color", str(tmp_file)]
+            )
+        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[36m", actual)
+        self.assertIn("\033[32m", actual)
+        self.assertIn("\033[31m", actual)
+        self.assertIn("\033[0m", actual)
+

     @patch("black.dump_to_file", dump_to_stderr)
     def test_fstring(self) -> None:
         source, expected = read_data("fstring")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fstring(self) -> None:
         source, expected = read_data("fstring")
         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)
 


@@ -358,20 +504,80 @@ 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)
         not_normalized = fs(source, mode=mode)

-        self.assertFormatEqual(source, not_normalized)
+        self.assertFormatEqual(source.replace("\\\n", ""), not_normalized)

         black.assert_equivalent(source, not_normalized)
         black.assert_stable(source, not_normalized, mode=mode)
 
         black.assert_equivalent(source, not_normalized)
         black.assert_stable(source, not_normalized, mode=mode)
 

+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_docstring(self) -> None:
+        source, expected = read_data("docstring")
+        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_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."""
+        source, expected = read_data("long_strings")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        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:
+        """Edge-case tests for splitting long strings."""
+        source, expected = read_data("long_strings__edge_case")
+        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_long_strings__regression(self) -> None:
+        """Regression tests for splitting long strings."""
+        source, expected = read_data("long_strings__regression")
+        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_slices(self) -> None:
         source, expected = read_data("slices")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
     @patch("black.dump_to_file", dump_to_stderr)
     def test_slices(self) -> None:
         source, expected = read_data("slices")
         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:
+        source, expected = read_data("percent_precedence")
+        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_comments(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments(self) -> None:


@@ -379,7 +585,7 @@ 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:


@@ -387,7 +593,7 @@ 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:


@@ -395,7 +601,7 @@ 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:


@@ -403,7 +609,7 @@ 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:


@@ -411,7 +617,7 @@ 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:


@@ -419,15 +625,16 @@ 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:


@@ -435,7 +642,7 @@ 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:


@@ -443,7 +650,7 @@ 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:


@@ -451,7 +658,7 @@ 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:


@@ -459,7 +666,16 @@ 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:


@@ -467,7 +683,7 @@ 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:


@@ -475,7 +691,7 @@ 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:


@@ -483,12 +699,12 @@ 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)


@@ -497,7 +713,7 @@ 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)


@@ -508,7 +724,7 @@ 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:


@@ -516,12 +732,12 @@ 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)


@@ -533,11 +749,11 @@ 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)


@@ -552,7 +768,7 @@ 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


@@ -567,19 +783,29 @@ 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
         self.invokeBlack([str(source_path), "--target-version", "py36"], exit_code=123)
 
         # 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
         self.invokeBlack([str(source_path), "--target-version", "py36"], exit_code=123)
 

+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_python38(self) -> None:
+        source, expected = read_data("python38")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        major, minor = sys.version_info[:2]
+        if major > 3 or (major == 3 and minor >= 8):
+            black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, DEFAULT_MODE)
+

     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff(self) -> None:
         source, expected = read_data("fmtonoff")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff(self) -> None:
         source, expected = read_data("fmtonoff")
         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:


@@ -587,7 +813,23 @@ 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:
+        source, expected = read_data("fmtonoff3")
+        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_fmtonoff4(self) -> None:
+        source, expected = read_data("fmtonoff4")
+        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_remove_empty_parentheses_after_class(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_remove_empty_parentheses_after_class(self) -> None:


@@ -595,7 +837,7 @@ 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:


@@ -603,7 +845,7 @@ 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:


@@ -611,7 +853,7 @@ 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:


@@ -619,7 +861,7 @@ 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:


@@ -627,7 +869,7 @@ 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"


@@ -695,8 +937,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(err_lines[-1], "error: cannot format e1: boom")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(err_lines[-1], "error: cannot format e1: boom")
             self.assertEqual(
                 unstyle(str(report)),

-                "1 file reformatted, 2 files left unchanged, "
-                "1 file failed to reformat.",
+                "1 file reformatted, 2 files left unchanged, 1 file failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f3"), black.Changed.YES)
             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f3"), black.Changed.YES)


@@ -705,8 +947,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(out_lines[-1], "reformatted f3")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(out_lines[-1], "reformatted f3")
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 2 files left unchanged, "
-                "1 file failed to reformat.",
+                "2 files reformatted, 2 files left unchanged, 1 file failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.failed(Path("e2"), "boom")
             )
             self.assertEqual(report.return_code, 123)
             report.failed(Path("e2"), "boom")


@@ -715,8 +957,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(err_lines[-1], "error: cannot format e2: boom")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(err_lines[-1], "error: cannot format e2: boom")
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 2 files left unchanged, "
-                "2 files failed to reformat.",
+                "2 files reformatted, 2 files left unchanged, 2 files failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.path_ignored(Path("wat"), "no match")
             )
             self.assertEqual(report.return_code, 123)
             report.path_ignored(Path("wat"), "no match")


@@ -725,8 +967,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(out_lines[-1], "wat ignored: no match")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(out_lines[-1], "wat ignored: no match")
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 2 files left unchanged, "
-                "2 files failed to reformat.",
+                "2 files reformatted, 2 files left unchanged, 2 files failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f4"), black.Changed.NO)
             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f4"), black.Changed.NO)


@@ -735,15 +977,22 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(out_lines[-1], "f4 already well formatted, good job.")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(out_lines[-1], "f4 already well formatted, good job.")
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 3 files left unchanged, "
-                "2 files failed to reformat.",
+                "2 files reformatted, 3 files left unchanged, 2 files failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.check = True
             self.assertEqual(
                 unstyle(str(report)),
             )
             self.assertEqual(report.return_code, 123)
             report.check = True
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files would be reformatted, 3 files would be left unchanged, "
-                "2 files would fail to reformat.",
+                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
+                " would fail to reformat.",
+            )
+            report.check = False
+            report.diff = True
+            self.assertEqual(
+                unstyle(str(report)),
+                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
+                " would fail to reformat.",

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


@@ -785,8 +1034,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(err_lines[-1], "error: cannot format e1: boom")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(err_lines[-1], "error: cannot format e1: boom")
             self.assertEqual(
                 unstyle(str(report)),

-                "1 file reformatted, 2 files left unchanged, "
-                "1 file failed to reformat.",
+                "1 file reformatted, 2 files left unchanged, 1 file failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f3"), black.Changed.YES)
             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f3"), black.Changed.YES)


@@ -794,8 +1043,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(len(err_lines), 1)
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(len(err_lines), 1)
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 2 files left unchanged, "
-                "1 file failed to reformat.",
+                "2 files reformatted, 2 files left unchanged, 1 file failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.failed(Path("e2"), "boom")
             )
             self.assertEqual(report.return_code, 123)
             report.failed(Path("e2"), "boom")


@@ -804,8 +1053,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(err_lines[-1], "error: cannot format e2: boom")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(err_lines[-1], "error: cannot format e2: boom")
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 2 files left unchanged, "
-                "2 files failed to reformat.",
+                "2 files reformatted, 2 files left unchanged, 2 files failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.path_ignored(Path("wat"), "no match")
             )
             self.assertEqual(report.return_code, 123)
             report.path_ignored(Path("wat"), "no match")


@@ -813,8 +1062,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(len(err_lines), 2)
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(len(err_lines), 2)
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 2 files left unchanged, "
-                "2 files failed to reformat.",
+                "2 files reformatted, 2 files left unchanged, 2 files failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f4"), black.Changed.NO)
             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f4"), black.Changed.NO)


@@ -822,15 +1071,22 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(len(err_lines), 2)
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(len(err_lines), 2)
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 3 files left unchanged, "
-                "2 files failed to reformat.",
+                "2 files reformatted, 3 files left unchanged, 2 files failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.check = True
             self.assertEqual(
                 unstyle(str(report)),
             )
             self.assertEqual(report.return_code, 123)
             report.check = True
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files would be reformatted, 3 files would be left unchanged, "
-                "2 files would fail to reformat.",
+                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
+                " would fail to reformat.",
+            )
+            report.check = False
+            report.diff = True
+            self.assertEqual(
+                unstyle(str(report)),
+                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
+                " would fail to reformat.",

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


@@ -874,8 +1130,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(err_lines[-1], "error: cannot format e1: boom")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(err_lines[-1], "error: cannot format e1: boom")
             self.assertEqual(
                 unstyle(str(report)),

-                "1 file reformatted, 2 files left unchanged, "
-                "1 file failed to reformat.",
+                "1 file reformatted, 2 files left unchanged, 1 file failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f3"), black.Changed.YES)
             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f3"), black.Changed.YES)


@@ -884,8 +1140,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(out_lines[-1], "reformatted f3")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(out_lines[-1], "reformatted f3")
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 2 files left unchanged, "
-                "1 file failed to reformat.",
+                "2 files reformatted, 2 files left unchanged, 1 file failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.failed(Path("e2"), "boom")
             )
             self.assertEqual(report.return_code, 123)
             report.failed(Path("e2"), "boom")


@@ -894,8 +1150,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(err_lines[-1], "error: cannot format e2: boom")
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(err_lines[-1], "error: cannot format e2: boom")
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 2 files left unchanged, "
-                "2 files failed to reformat.",
+                "2 files reformatted, 2 files left unchanged, 2 files failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.path_ignored(Path("wat"), "no match")
             )
             self.assertEqual(report.return_code, 123)
             report.path_ignored(Path("wat"), "no match")


@@ -903,8 +1159,8 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(len(err_lines), 2)
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(len(err_lines), 2)
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 2 files left unchanged, "
-                "2 files failed to reformat.",
+                "2 files reformatted, 2 files left unchanged, 2 files failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f4"), black.Changed.NO)
             )
             self.assertEqual(report.return_code, 123)
             report.done(Path("f4"), black.Changed.NO)


@@ -912,15 +1168,22 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(len(err_lines), 2)
             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(len(err_lines), 2)
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files reformatted, 3 files left unchanged, "
-                "2 files failed to reformat.",
+                "2 files reformatted, 3 files left unchanged, 2 files failed to"
+                " reformat.",

             )
             self.assertEqual(report.return_code, 123)
             report.check = True
             self.assertEqual(
                 unstyle(str(report)),
             )
             self.assertEqual(report.return_code, 123)
             report.check = True
             self.assertEqual(
                 unstyle(str(report)),

-                "2 files would be reformatted, 3 files would be left unchanged, "
-                "2 files would fail to reformat.",
+                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
+                " would fail to reformat.",
+            )
+            report.check = False
+            report.diff = True
+            self.assertEqual(
+                unstyle(str(report)),
+                "2 files would be reformatted, 3 files would be left unchanged, 2 files"
+                " would fail to reformat.",

             )
 
     def test_lib2to3_parse(self) -> None:
             )
 
     def test_lib2to3_parse(self) -> None:


@@ -1035,16 +1298,16 @@ 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(just_nl, mode=mode, fast=False)
         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(just_nl, mode=mode, fast=False)

-        same = "l = [1, 2, 3]\n"
+        same = "j = [1, 2, 3]\n"

         with self.assertRaises(black.NothingChanged):
             black.format_file_contents(same, mode=mode, fast=False)
         with self.assertRaises(black.NothingChanged):
             black.format_file_contents(same, mode=mode, fast=False)

-        different = "l = [1,2,3]"
+        different = "j = [1,2,3]"

         expected = same
         actual = black.format_file_contents(different, mode=mode, fast=False)
         self.assertEqual(expected, actual)
         expected = same
         actual = black.format_file_contents(different, mode=mode, fast=False)
         self.assertEqual(expected, actual)


@@ -1072,7 +1335,7 @@ class BlackTestCase(unittest.TestCase):
 
         with patch("black.out", out), patch("black.err", err):
             with self.assertRaises(AssertionError):
 
         with patch("black.out", out), patch("black.err", err):
             with self.assertRaises(AssertionError):

-                self.assertFormatEqual("l = [1, 2, 3]", "l = [1, 2, 3,]")
+                self.assertFormatEqual("j = [1, 2, 3]", "j = [1, 2, 3,]")

 
         out_str = "".join(out_lines)
         self.assertTrue("Expected tree:" in out_str)
 
         out_str = "".join(out_lines)
         self.assertTrue("Expected tree:" in out_str)


@@ -1080,7 +1343,7 @@ 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:


@@ -1094,7 +1357,7 @@ 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:


@@ -1104,9 +1367,9 @@ class BlackTestCase(unittest.TestCase):
             with src.open("r") as fobj:
                 self.assertEqual(fobj.read(), "print('hello')")
 
             with src.open("r") as fobj:
                 self.assertEqual(fobj.read(), "print('hello')")
 

-    @event_loop(close=False)
+    @event_loop()

     def test_cache_multiple_files(self) -> None:
     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
         ):


@@ -1127,7 +1390,7 @@ 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:
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             with src.open("w") as fobj:


@@ -1137,7 +1400,7 @@ class BlackTestCase(unittest.TestCase):
             self.assertFalse(cache_file.exists())
 
     def test_no_cache_when_stdin(self) -> None:
             self.assertFalse(cache_file.exists())
 
     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')")


@@ -1147,12 +1410,12 @@ 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()


@@ -1178,15 +1441,15 @@ 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)
             self.assertTrue(workspace.exists())
 
         with cache_dir(exists=False) as workspace:
             self.assertFalse(workspace.exists())
             black.write_cache({}, [], mode)
             self.assertTrue(workspace.exists())
 

-    @event_loop(close=False)
+    @event_loop()

     def test_failed_formatting_does_not_get_cached(self) -> None:
     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
         ):


@@ -1202,12 +1465,23 @@ 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)
 

-    @event_loop(close=False)
+    @event_loop()
+    @patch("black.ProcessPoolExecutor", MagicMock(side_effect=OSError))
+    def test_works_in_mono_process_only_environment(self) -> None:
+        with cache_dir() as workspace:
+            for f in [
+                (workspace / "one.py").resolve(),
+                (workspace / "two.py").resolve(),
+            ]:
+                f.write_text('print("hello")\n')
+            self.invokeBlack([str(workspace)])
+
+    @event_loop()

     def test_check_diff_use_together(self) -> None:
         with cache_dir():
             # Files which will be reformatted.
     def test_check_diff_use_together(self) -> None:
         with cache_dir():
             # Files which will be reformatted.


@@ -1234,8 +1508,8 @@ 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()


@@ -1245,9 +1519,16 @@ class BlackTestCase(unittest.TestCase):
             two = black.read_cache(short_mode)
             self.assertNotIn(path, two)
 
             two = black.read_cache(short_mode)
             self.assertNotIn(path, two)
 

+    def test_tricky_unicode_symbols(self) -> None:
+        source, expected = read_data("tricky_unicode_symbols")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        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()


@@ -1263,10 +1544,10 @@ class BlackTestCase(unittest.TestCase):
             self.assertNotIn(path, normal_cache)
         self.assertEqual(actual, expected)
 
             self.assertNotIn(path, normal_cache)
         self.assertEqual(actual, expected)
 

-    @event_loop(close=False)
+    @event_loop()

     def test_multi_file_force_pyi(self) -> None:
     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 = [


@@ -1298,8 +1579,8 @@ 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()


@@ -1315,10 +1596,10 @@ class BlackTestCase(unittest.TestCase):
             self.assertNotIn(path, normal_cache)
         self.assertEqual(actual, expected)
 
             self.assertNotIn(path, normal_cache)
         self.assertEqual(actual, expected)
 

-    @event_loop(close=False)
+    @event_loop()

     def test_multi_file_force_py36(self) -> None:
     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 = [


@@ -1340,6 +1621,13 @@ class BlackTestCase(unittest.TestCase):
                 self.assertIn(path, pyi_cache)
                 self.assertNotIn(path, normal_cache)
 
                 self.assertIn(path, pyi_cache)
                 self.assertNotIn(path, normal_cache)
 

+    def test_collections(self) -> None:
+        source, expected = read_data("collections")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, DEFAULT_MODE)
+

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


@@ -1356,6 +1644,53 @@ class BlackTestCase(unittest.TestCase):
         include = re.compile(r"\.pyi?$")
         exclude = re.compile(r"/exclude/|/\.definitely_exclude/")
         report = black.Report()
         include = re.compile(r"\.pyi?$")
         exclude = re.compile(r"/exclude/|/\.definitely_exclude/")
         report = black.Report()

+        gitignore = PathSpec.from_lines("gitwildmatch", [])
+        sources: List[Path] = []
+        expected = [
+            Path(path / "b/dont_exclude/a.py"),
+            Path(path / "b/dont_exclude/a.pyi"),
+        ]
+        this_abs = THIS_DIR.resolve()
+        sources.extend(
+            black.gen_python_files(
+                path.iterdir(), this_abs, include, exclude, None, report, gitignore
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    def test_exclude_for_issue_1572(self) -> None:
+        # Exclude shouldn't touch files that were explicitly given to Black through the
+        # CLI. Exclude is supposed to only apply to the recursive discovery of files.
+        # https://github.com/psf/black/issues/1572
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        include = ""
+        exclude = r"/exclude/|a\.py"
+        src = str(path / "b/exclude/a.py")
+        report = black.Report()
+        expected = [Path(path / "b/exclude/a.py")]
+        sources = list(
+            black.get_sources(
+                ctx=FakeContext(),
+                src=(src,),
+                quiet=True,
+                verbose=False,
+                include=include,
+                exclude=exclude,
+                force_exclude=None,
+                report=report,
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    def test_gitignore_exclude(self) -> None:
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        include = re.compile(r"\.pyi?$")
+        exclude = re.compile(r"")
+        report = black.Report()
+        gitignore = PathSpec.from_lines(
+            "gitwildmatch", ["exclude/", ".definitely_exclude"]
+        )

         sources: List[Path] = []
         expected = [
             Path(path / "b/dont_exclude/a.py"),
         sources: List[Path] = []
         expected = [
             Path(path / "b/dont_exclude/a.py"),


@@ -1363,13 +1698,16 @@ class BlackTestCase(unittest.TestCase):
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(

-            black.gen_python_files_in_dir(path, this_abs, include, exclude, report)
+            black.gen_python_files(
+                path.iterdir(), this_abs, include, exclude, None, report, gitignore
+            )

         )
         self.assertEqual(sorted(expected), sorted(sources))
 
     def test_empty_include(self) -> None:
         path = THIS_DIR / "data" / "include_exclude_tests"
         report = black.Report()
         )
         self.assertEqual(sorted(expected), sorted(sources))
 
     def test_empty_include(self) -> None:
         path = THIS_DIR / "data" / "include_exclude_tests"
         report = black.Report()

+        gitignore = PathSpec.from_lines("gitwildmatch", [])

         empty = re.compile(r"")
         sources: List[Path] = []
         expected = [
         empty = re.compile(r"")
         sources: List[Path] = []
         expected = [


@@ -1385,8 +1723,14 @@ class BlackTestCase(unittest.TestCase):
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(

-            black.gen_python_files_in_dir(
-                path, this_abs, empty, re.compile(black.DEFAULT_EXCLUDES), report
+            black.gen_python_files(
+                path.iterdir(),
+                this_abs,
+                empty,
+                re.compile(black.DEFAULT_EXCLUDES),
+                None,
+                report,
+                gitignore,

             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))


@@ -1394,6 +1738,7 @@ class BlackTestCase(unittest.TestCase):
     def test_empty_exclude(self) -> None:
         path = THIS_DIR / "data" / "include_exclude_tests"
         report = black.Report()
     def test_empty_exclude(self) -> None:
         path = THIS_DIR / "data" / "include_exclude_tests"
         report = black.Report()

+        gitignore = PathSpec.from_lines("gitwildmatch", [])

         empty = re.compile(r"")
         sources: List[Path] = []
         expected = [
         empty = re.compile(r"")
         sources: List[Path] = []
         expected = [


@@ -1406,8 +1751,14 @@ class BlackTestCase(unittest.TestCase):
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(

-            black.gen_python_files_in_dir(
-                path, this_abs, re.compile(black.DEFAULT_INCLUDES), empty, report
+            black.gen_python_files(
+                path.iterdir(),
+                this_abs,
+                re.compile(black.DEFAULT_INCLUDES),
+                empty,
+                None,
+                report,
+                gitignore,

             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))


@@ -1447,18 +1798,24 @@ class BlackTestCase(unittest.TestCase):
 
     def test_symlink_out_of_root_directory(self) -> None:
         path = MagicMock()
 
     def test_symlink_out_of_root_directory(self) -> None:
         path = MagicMock()

-        root = THIS_DIR
+        root = THIS_DIR.resolve()

         child = MagicMock()
         include = re.compile(black.DEFAULT_INCLUDES)
         exclude = re.compile(black.DEFAULT_EXCLUDES)
         report = black.Report()
         child = MagicMock()
         include = re.compile(black.DEFAULT_INCLUDES)
         exclude = re.compile(black.DEFAULT_EXCLUDES)
         report = black.Report()

+        gitignore = PathSpec.from_lines("gitwildmatch", [])

         # `child` should behave like a symlink which resolved path is clearly
         # outside of the `root` directory.
         path.iterdir.return_value = [child]
         child.resolve.return_value = Path("/a/b/c")
         # `child` should behave like a symlink which resolved path is clearly
         # outside of the `root` directory.
         path.iterdir.return_value = [child]
         child.resolve.return_value = Path("/a/b/c")

+        child.as_posix.return_value = "/a/b/c"

         child.is_symlink.return_value = True
         try:
         child.is_symlink.return_value = True
         try:

-            list(black.gen_python_files_in_dir(path, root, include, exclude, report))
+            list(
+                black.gen_python_files(
+                    path.iterdir(), root, include, exclude, None, report, gitignore
+                )
+            )

         except ValueError as ve:
             self.fail(f"`get_python_files_in_dir()` failed: {ve}")
         path.iterdir.assert_called_once()
         except ValueError as ve:
             self.fail(f"`get_python_files_in_dir()` failed: {ve}")
         path.iterdir.assert_called_once()


@@ -1468,7 +1825,11 @@ class BlackTestCase(unittest.TestCase):
         # outside of the `root` directory.
         child.is_symlink.return_value = False
         with self.assertRaises(ValueError):
         # outside of the `root` directory.
         child.is_symlink.return_value = False
         with self.assertRaises(ValueError):

-            list(black.gen_python_files_in_dir(path, root, include, exclude, report))
+            list(
+                black.gen_python_files(
+                    path.iterdir(), root, include, exclude, None, report, gitignore
+                )
+            )

         path.iterdir.assert_called()
         self.assertEqual(path.iterdir.call_count, 2)
         child.resolve.assert_called()
         path.iterdir.assert_called()
         self.assertEqual(path.iterdir.call_count, 2)
         child.resolve.assert_called()


@@ -1521,6 +1882,81 @@ class BlackTestCase(unittest.TestCase):
                 raise result.exception
             self.assertEqual(result.exit_code, 0)
 
                 raise result.exception
             self.assertEqual(result.exit_code, 0)
 

+    def test_invalid_config_return_code(self) -> None:
+        tmp_file = Path(black.dump_to_file())
+        try:
+            tmp_config = Path(black.dump_to_file())
+            tmp_config.unlink()
+            args = ["--config", str(tmp_config), str(tmp_file)]
+            self.invokeBlack(args, exit_code=2, ignore_config=False)
+        finally:
+            tmp_file.unlink()
+
+    def test_parse_pyproject_toml(self) -> None:
+        test_toml_file = THIS_DIR / "test.toml"
+        config = black.parse_pyproject_toml(str(test_toml_file))
+        self.assertEqual(config["verbose"], 1)
+        self.assertEqual(config["check"], "no")
+        self.assertEqual(config["diff"], "y")
+        self.assertEqual(config["color"], True)
+        self.assertEqual(config["line_length"], 79)
+        self.assertEqual(config["target_version"], ["py36", "py37", "py38"])
+        self.assertEqual(config["exclude"], r"\.pyi?$")
+        self.assertEqual(config["include"], r"\.py?$")
+
+    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))
+        config = fake_ctx.default_map
+        self.assertEqual(config["verbose"], "1")
+        self.assertEqual(config["check"], "no")
+        self.assertEqual(config["diff"], "y")
+        self.assertEqual(config["color"], "True")
+        self.assertEqual(config["line_length"], "79")
+        self.assertEqual(config["target_version"], ["py36", "py37", "py38"])
+        self.assertEqual(config["exclude"], r"\.pyi?$")
+        self.assertEqual(config["include"], r"\.py?$")
+
+    def test_find_project_root(self) -> None:
+        with TemporaryDirectory() as workspace:
+            root = Path(workspace)
+            test_dir = root / "test"
+            test_dir.mkdir()
+
+            src_dir = root / "src"
+            src_dir.mkdir()
+
+            root_pyproject = root / "pyproject.toml"
+            root_pyproject.touch()
+            src_pyproject = src_dir / "pyproject.toml"
+            src_pyproject.touch()
+            src_python = src_dir / "foo.py"
+            src_python.touch()
+
+            self.assertEqual(
+                black.find_project_root((src_dir, test_dir)), root.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:


@@ -1562,7 +1998,7 @@ class BlackDTestCase(AioHTTPTestCase):
     @unittest_run_loop
     async def test_blackd_unsupported_version(self) -> None:
         response = await self.client.post(
     @unittest_run_loop
     async def test_blackd_unsupported_version(self) -> None:
         response = await self.client.post(

-            "/", data=b"what", headers={blackd.VERSION_HEADER: "2"}
+            "/", data=b"what", headers={blackd.PROTOCOL_VERSION_HEADER: "2"}

         )
         self.assertEqual(response.status, 501)
 
         )
         self.assertEqual(response.status, 501)
 


@@ -1571,7 +2007,7 @@ class BlackDTestCase(AioHTTPTestCase):
     @unittest_run_loop
     async def test_blackd_supported_version(self) -> None:
         response = await self.client.post(
     @unittest_run_loop
     async def test_blackd_supported_version(self) -> None:
         response = await self.client.post(

-            "/", data=b"what", headers={blackd.VERSION_HEADER: "1"}
+            "/", data=b"what", headers={blackd.PROTOCOL_VERSION_HEADER: "1"}

         )
         self.assertEqual(response.status, 200)
 
         )
         self.assertEqual(response.status, 200)
 


@@ -1606,6 +2042,26 @@ class BlackDTestCase(AioHTTPTestCase):
         self.assertEqual(response.status, 200)
         self.assertEqual(await response.text(), expected)
 
         self.assertEqual(response.status, 200)
         self.assertEqual(await response.text(), expected)
 

+    @skip_if_exception("ClientOSError")
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @unittest_run_loop
+    async def test_blackd_diff(self) -> None:
+        diff_header = re.compile(
+            r"(In|Out)\t\d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
+        )
+
+        source, _ = read_data("blackd_diff.py")
+        expected, _ = read_data("blackd_diff.diff")
+
+        response = await self.client.post(
+            "/", data=source, headers={blackd.DIFF_HEADER: "true"}
+        )
+        self.assertEqual(response.status, 200)
+
+        actual = await response.text()
+        actual = diff_header.sub(DETERMINISTIC_HEADER, actual)
+        self.assertEqual(actual, expected)
+

     @skip_if_exception("ClientOSError")
     @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
     @unittest_run_loop
     @skip_if_exception("ClientOSError")
     @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
     @unittest_run_loop


@@ -1624,18 +2080,25 @@ class BlackDTestCase(AioHTTPTestCase):
             response = await self.client.post(
                 "/", data=code, headers={blackd.PYTHON_VARIANT_HEADER: header_value}
             )
             response = await self.client.post(
                 "/", data=code, headers={blackd.PYTHON_VARIANT_HEADER: header_value}
             )

-            self.assertEqual(response.status, expected_status)
+            self.assertEqual(
+                response.status, expected_status, msg=await response.text()
+            )

 
         await check("3.6", 200)
         await check("py3.6", 200)
         await check("3.6,3.7", 200)
         await check("3.6,py3.7", 200)
 
         await check("3.6", 200)
         await check("py3.6", 200)
         await check("3.6,3.7", 200)
         await check("3.6,py3.7", 200)

+        await check("py36,py37", 200)
+        await check("36", 200)
+        await check("3.6.4", 200)

 
         await check("2", 204)
         await check("2.7", 204)
         await check("py2.7", 204)
         await check("3.4", 204)
         await check("py3.4", 204)
 
         await check("2", 204)
         await check("2.7", 204)
         await check("py2.7", 204)
         await check("3.4", 204)
         await check("py3.4", 204)

+        await check("py34,py36", 204)
+        await check("34", 204)

 
     @skip_if_exception("ClientOSError")
     @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
 
     @skip_if_exception("ClientOSError")
     @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")


@@ -1655,6 +2118,39 @@ class BlackDTestCase(AioHTTPTestCase):
         )
         self.assertEqual(response.status, 400)
 
         )
         self.assertEqual(response.status, 400)
 

+    @skip_if_exception("ClientOSError")
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @unittest_run_loop
+    async def test_blackd_response_black_version_header(self) -> None:
+        response = await self.client.post("/")
+        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")