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Prepare CHANGES.md for release 21.8b0 (#2458)
[etc/vim.git] / tests / test_black.py
index edcf7208b46aa685166dad061640cb8531c5717e..398a528bee9a4684fd52355597fcbc1f3bf0d3c3 100644 (file)
@@ -5,9 +5,9 @@ import logging
 from concurrent.futures import ThreadPoolExecutor
 from contextlib import contextmanager
 from dataclasses import replace
-from functools import partial
 import inspect
-from io import BytesIO, TextIOWrapper
+import io
+from io import BytesIO
 import os
 from pathlib import Path
 from platform import system
@@ -17,17 +17,16 @@ from tempfile import TemporaryDirectory
 import types
 from typing import (
     Any,
-    BinaryIO,
     Callable,
     Dict,
-    Generator,
     List,
-    Tuple,
     Iterator,
     TypeVar,
 )
+import pytest
 import unittest
 from unittest.mock import patch, MagicMock
+from parameterized import parameterized
 
 import click
 from click import unstyle
@@ -35,62 +34,41 @@ from click.testing import CliRunner
 
 import black
 from black import Feature, TargetVersion
-
-try:
-    import blackd
-    from aiohttp.test_utils import AioHTTPTestCase, unittest_run_loop
-    from aiohttp import web
-except ImportError:
-    has_blackd_deps = False
-else:
-    has_blackd_deps = True
+from black.cache import get_cache_file
+from black.debug import DebugVisitor
+from black.output import diff, color_diff
+from black.report import Report
+import black.files
 
 from pathspec import PathSpec
 
 # Import other test classes
-from .test_primer import PrimerCLITests  # noqa: F401
+from tests.util import (
+    THIS_DIR,
+    change_directory,
+    read_data,
+    DETERMINISTIC_HEADER,
+    BlackBaseTestCase,
+    DEFAULT_MODE,
+    fs,
+    ff,
+    dump_to_stderr,
+)
 
 
-DEFAULT_MODE = black.FileMode(experimental_string_processing=True)
-ff = partial(black.format_file_in_place, mode=DEFAULT_MODE, fast=True)
-fs = partial(black.format_str, mode=DEFAULT_MODE)
 THIS_FILE = Path(__file__)
-THIS_DIR = THIS_FILE.parent
-PROJECT_ROOT = THIS_DIR.parent
-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
-]
+PY36_VERSIONS = {
+    TargetVersion.PY36,
+    TargetVersion.PY37,
+    TargetVersion.PY38,
+    TargetVersion.PY39,
+}
+PY36_ARGS = [f"--target-version={version.name.lower()}" for version in PY36_VERSIONS]
 T = TypeVar("T")
 R = TypeVar("R")
 
-
-def dump_to_stderr(*output: str) -> str:
-    return "\n" + "\n".join(output) + "\n"
-
-
-def read_data(name: str, data: bool = True) -> Tuple[str, str]:
-    """read_data('test_name') -> 'input', 'output'"""
-    if not name.endswith((".py", ".pyi", ".out", ".diff")):
-        name += ".py"
-    _input: List[str] = []
-    _output: List[str] = []
-    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
-    for line in lines:
-        line = line.replace(EMPTY_LINE, "")
-        if line.rstrip() == "# output":
-            result = _output
-            continue
-
-        result.append(line)
-    if _input and not _output:
-        # If there's no output marker, treat the entire file as already pre-formatted.
-        _output = _input[:]
-    return "".join(_input).strip() + "\n", "".join(_output).strip() + "\n"
+# Match the time output in a diff, but nothing else
+DIFF_TIME = re.compile(r"\t[\d-:+\. ]+")
 
 
 @contextmanager
@@ -99,7 +77,7 @@ def cache_dir(exists: bool = True) -> Iterator[Path]:
         cache_dir = Path(workspace)
         if not exists:
             cache_dir = cache_dir / "new"
-        with patch("black.CACHE_DIR", cache_dir):
+        with patch("black.cache.CACHE_DIR", cache_dir):
             yield cache_dir
 
 
@@ -115,17 +93,6 @@ def event_loop() -> Iterator[None]:
         loop.close()
 
 
-@contextmanager
-def skip_if_exception(e: str) -> Iterator[None]:
-    try:
-        yield
-    except Exception as exc:
-        if exc.__class__.__name__ == e:
-            unittest.skip(f"Encountered expected exception {exc}, skipping")
-        else:
-            raise
-
-
 class FakeContext(click.Context):
     """A fake click Context for when calling functions that need it."""
 
@@ -141,53 +108,13 @@ class FakeParameter(click.Parameter):
 
 
 class BlackRunner(CliRunner):
-    """Modify CliRunner so that stderr is not merged with stdout.
-
-    This is a hack that can be removed once we depend on Click 7.x"""
+    """Make sure STDOUT and STDERR are kept separate when testing Black via its CLI."""
 
     def __init__(self) -> None:
-        self.stderrbuf = BytesIO()
-        self.stdoutbuf = BytesIO()
-        self.stdout_bytes = b""
-        self.stderr_bytes = b""
-        super().__init__()
-
-    @contextmanager
-    def isolation(self, *args: Any, **kwargs: Any) -> Generator[BinaryIO, None, None]:
-        with super().isolation(*args, **kwargs) as output:
-            try:
-                hold_stderr = sys.stderr
-                sys.stderr = TextIOWrapper(self.stderrbuf, encoding=self.charset)
-                yield output
-            finally:
-                self.stdout_bytes = sys.stdout.buffer.getvalue()  # type: ignore
-                self.stderr_bytes = sys.stderr.buffer.getvalue()  # type: ignore
-                sys.stderr = hold_stderr
-
-
-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"):
-            bdv: black.DebugVisitor[Any]
-            black.out("Expected tree:", fg="green")
-            try:
-                exp_node = black.lib2to3_parse(expected)
-                bdv = black.DebugVisitor()
-                list(bdv.visit(exp_node))
-            except Exception as ve:
-                black.err(str(ve))
-            black.out("Actual tree:", fg="red")
-            try:
-                exp_node = black.lib2to3_parse(actual)
-                bdv = black.DebugVisitor()
-                list(bdv.visit(exp_node))
-            except Exception as ve:
-                black.err(str(ve))
-        self.assertMultiLineEqual(expected, actual)
+        super().__init__(mix_stderr=False)
+
 
+class BlackTestCase(BlackBaseTestCase):
     def invokeBlack(
         self, args: List[str], exit_code: int = 0, ignore_config: bool = True
     ) -> None:
@@ -195,27 +122,19 @@ class BlackTestCase(unittest.TestCase):
         if ignore_config:
             args = ["--verbose", "--config", str(THIS_DIR / "empty.toml"), *args]
         result = runner.invoke(black.main, args)
+        assert result.stdout_bytes is not None
+        assert result.stderr_bytes is not None
         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"stdout: {result.stdout_bytes.decode()!r}\n"
+                f"stderr: {result.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:
         source = expected = ""
@@ -235,45 +154,6 @@ class BlackTestCase(unittest.TestCase):
             os.unlink(tmp_file)
         self.assertFormatEqual(expected, actual)
 
-    def test_self(self) -> None:
-        self.checkSourceFile("tests/test_black.py")
-
-    def test_black(self) -> None:
-        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:
         source, expected = read_data("src/black/__init__", data=False)
         result = BlackRunner().invoke(
@@ -283,8 +163,9 @@ class BlackTestCase(unittest.TestCase):
         )
         self.assertEqual(result.exit_code, 0)
         self.assertFormatEqual(expected, result.output)
-        black.assert_equivalent(source, result.output)
-        black.assert_stable(source, result.output, DEFAULT_MODE)
+        if source != result.output:
+            black.assert_equivalent(source, result.output)
+            black.assert_stable(source, result.output, DEFAULT_MODE)
 
     def test_piping_diff(self) -> None:
         diff_header = re.compile(
@@ -331,22 +212,6 @@ class BlackTestCase(unittest.TestCase):
         self.assertIn("\033[31m", actual)
         self.assertIn("\033[0m", actual)
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_function(self) -> None:
-        source, expected = read_data("function")
-        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_function2(self) -> None:
-        source, expected = read_data("function2")
-        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")
@@ -362,14 +227,6 @@ class BlackTestCase(unittest.TestCase):
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, black.FileMode())
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_function_trailing_comma(self) -> None:
-        source, expected = read_data("function_trailing_comma")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        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:
@@ -392,11 +249,21 @@ class BlackTestCase(unittest.TestCase):
         black.assert_stable(source, actual, DEFAULT_MODE)
 
     @patch("black.dump_to_file", dump_to_stderr)
-    def test_expression(self) -> None:
-        source, expected = read_data("expression")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
+    def test_trailing_comma_optional_parens_stability1_pass2(self) -> None:
+        source, _expected = read_data("trailing_comma_optional_parens1")
+        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
+        black.assert_stable(source, actual, DEFAULT_MODE)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_trailing_comma_optional_parens_stability2_pass2(self) -> None:
+        source, _expected = read_data("trailing_comma_optional_parens2")
+        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
+        black.assert_stable(source, actual, DEFAULT_MODE)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_trailing_comma_optional_parens_stability3_pass2(self) -> None:
+        source, _expected = read_data("trailing_comma_optional_parens3")
+        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
         black.assert_stable(source, actual, DEFAULT_MODE)
 
     @patch("black.dump_to_file", dump_to_stderr)
@@ -408,6 +275,23 @@ class BlackTestCase(unittest.TestCase):
         if sys.version_info >= (3, 8):
             black.assert_equivalent(source, actual)
 
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_pep_572_remove_parens(self) -> None:
+        source, expected = read_data("pep_572_remove_parens")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_stable(source, actual, DEFAULT_MODE)
+        if sys.version_info >= (3, 8):
+            black.assert_equivalent(source, actual)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_pep_572_do_not_remove_parens(self) -> None:
+        source, expected = read_data("pep_572_do_not_remove_parens")
+        # the AST safety checks will fail, but that's expected, just make sure no
+        # parentheses are touched
+        actual = black.format_str(source, mode=DEFAULT_MODE)
+        self.assertFormatEqual(expected, actual)
+
     def test_pep_572_version_detection(self) -> None:
         source, _ = read_data("pep_572")
         root = black.lib2to3_parse(source)
@@ -416,6 +300,14 @@ class BlackTestCase(unittest.TestCase):
         versions = black.detect_target_versions(root)
         self.assertIn(black.TargetVersion.PY38, versions)
 
+    @parameterized.expand([(3, 9), (3, 10)])
+    def test_pep_572_newer_syntax(self, major: int, minor: int) -> None:
+        source, expected = read_data(f"pep_572_py{major}{minor}")
+        actual = fs(source, mode=DEFAULT_MODE)
+        self.assertFormatEqual(expected, actual)
+        if sys.version_info >= (major, minor):
+            black.assert_equivalent(source, actual)
+
     def test_expression_ff(self) -> None:
         source, expected = read_data("expression")
         tmp_file = Path(black.dump_to_file(source))
@@ -432,6 +324,7 @@ class BlackTestCase(unittest.TestCase):
 
     def test_expression_diff(self) -> None:
         source, _ = read_data("expression.py")
+        config = THIS_DIR / "data" / "empty_pyproject.toml"
         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         diff_header = re.compile(
@@ -439,13 +332,14 @@ class BlackTestCase(unittest.TestCase):
             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)])
+            result = BlackRunner().invoke(
+                black.main, ["--diff", str(tmp_file), f"--config={config}"]
+            )
             self.assertEqual(result.exit_code, 0)
         finally:
             os.unlink(tmp_file)
         actual = result.output
         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 = (
@@ -457,11 +351,12 @@ class BlackTestCase(unittest.TestCase):
 
     def test_expression_diff_with_color(self) -> None:
         source, _ = read_data("expression.py")
+        config = THIS_DIR / "data" / "empty_pyproject.toml"
         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         try:
             result = BlackRunner().invoke(
-                black.main, ["--diff", "--color", str(tmp_file)]
+                black.main, ["--diff", "--color", str(tmp_file), f"--config={config}"]
             )
         finally:
             os.unlink(tmp_file)
@@ -474,14 +369,6 @@ class BlackTestCase(unittest.TestCase):
         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)
-        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")
@@ -502,24 +389,17 @@ class BlackTestCase(unittest.TestCase):
     @patch("black.dump_to_file", dump_to_stderr)
     def test_string_quotes(self) -> None:
         source, expected = read_data("string_quotes")
-        actual = fs(source)
+        mode = black.Mode(experimental_string_processing=True)
+        actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-        mode = replace(DEFAULT_MODE, string_normalization=False)
+        black.assert_stable(source, actual, mode)
+        mode = replace(mode, string_normalization=False)
         not_normalized = fs(source, mode=mode)
         self.assertFormatEqual(source.replace("\\\n", ""), not_normalized)
         black.assert_equivalent(source, not_normalized)
         black.assert_stable(source, not_normalized, mode=mode)
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_docstring(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."""
@@ -530,14 +410,6 @@ class BlackTestCase(unittest.TestCase):
         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")
@@ -546,166 +418,10 @@ class BlackTestCase(unittest.TestCase):
         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)
-        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:
-        source, expected = read_data("comments")
-        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_comments2(self) -> None:
-        source, expected = read_data("comments2")
-        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_comments3(self) -> None:
-        source, expected = read_data("comments3")
-        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_comments4(self) -> None:
-        source, expected = read_data("comments4")
-        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_comments5(self) -> None:
-        source, expected = read_data("comments5")
-        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_comments6(self) -> None:
-        source, expected = read_data("comments6")
-        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_comments7(self) -> None:
-        source, expected = read_data("comments7")
-        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_comment_after_escaped_newline(self) -> None:
-        source, expected = read_data("comment_after_escaped_newline")
-        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_cantfit(self) -> None:
-        source, expected = read_data("cantfit")
-        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_import_spacing(self) -> None:
-        source, expected = read_data("import_spacing")
-        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_composition(self) -> None:
-        source, expected = read_data("composition")
-        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_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:
-        source, expected = read_data("empty_lines")
-        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_parens(self) -> None:
-        source, expected = read_data("remove_parens")
-        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_string_prefixes(self) -> None:
-        source, expected = read_data("string_prefixes")
-        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_numeric_literals(self) -> None:
         source, expected = read_data("numeric_literals")
-        mode = replace(DEFAULT_MODE, target_versions=black.PY36_VERSIONS)
+        mode = replace(DEFAULT_MODE, target_versions=PY36_VERSIONS)
         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
@@ -714,27 +430,38 @@ 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")
-        mode = replace(DEFAULT_MODE, target_versions=black.PY36_VERSIONS)
+        mode = replace(DEFAULT_MODE, target_versions=PY36_VERSIONS)
         actual = fs(source, mode=mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, mode)
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_numeric_literals_py2(self) -> None:
-        source, expected = read_data("numeric_literals_py2")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_python2(self) -> None:
-        source, expected = read_data("python2")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, DEFAULT_MODE)
+    def test_skip_magic_trailing_comma(self) -> None:
+        source, _ = read_data("expression.py")
+        expected, _ = read_data("expression_skip_magic_trailing_comma.diff")
+        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 "
+            r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
+        )
+        try:
+            result = BlackRunner().invoke(black.main, ["-C", "--diff", str(tmp_file)])
+            self.assertEqual(result.exit_code, 0)
+        finally:
+            os.unlink(tmp_file)
+        actual = result.output
+        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 = (
+                "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_skip_magic_trailing_comma.diff with {dump}"
+            )
+            self.assertEqual(expected, actual, msg)
 
+    @pytest.mark.python2
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2_print_function(self) -> None:
         source, expected = read_data("python2_print_function")
@@ -744,14 +471,6 @@ class BlackTestCase(unittest.TestCase):
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, mode)
 
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_python2_unicode_literals(self) -> None:
-        source, expected = read_data("python2_unicode_literals")
-        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_stub(self) -> None:
         mode = replace(DEFAULT_MODE, is_pyi=True)
@@ -770,106 +489,44 @@ class BlackTestCase(unittest.TestCase):
         if major < 3 or (major <= 3 and minor < 7):
             black.assert_equivalent(source, actual)
         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
-        self.invokeBlack([str(source_path), "--target-version", "py37"], exit_code=123)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_python37(self) -> None:
-        source_path = (THIS_DIR / "data" / "python37.py").resolve()
-        source, expected = read_data("python37")
-        actual = fs(source)
-        self.assertFormatEqual(expected, 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, 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)
-
-    @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)
-        black.assert_stable(source, actual, DEFAULT_MODE)
-
-    @patch("black.dump_to_file", dump_to_stderr)
-    def test_fmtonoff2(self) -> None:
-        source, expected = read_data("fmtonoff2")
-        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_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:
-        source, expected = read_data("class_blank_parentheses")
-        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_new_line_between_class_and_code(self) -> None:
-        source, expected = read_data("class_methods_new_line")
-        actual = fs(source)
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        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
+        self.invokeBlack([str(source_path), "--target-version", "py37"], exit_code=123)
 
     @patch("black.dump_to_file", dump_to_stderr)
-    def test_bracket_match(self) -> None:
-        source, expected = read_data("bracketmatch")
+    def test_python37(self) -> None:
+        source_path = (THIS_DIR / "data" / "python37.py").resolve()
+        source, expected = read_data("python37")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
-        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, 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)
 
     @patch("black.dump_to_file", dump_to_stderr)
-    def test_tuple_assign(self) -> None:
-        source, expected = read_data("tupleassign")
+    def test_python38(self) -> None:
+        source, expected = read_data("python38")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
+        major, minor = sys.version_info[:2]
+        if major > 3 or (major == 3 and minor >= 8):
+            black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, DEFAULT_MODE)
 
     @patch("black.dump_to_file", dump_to_stderr)
-    def test_beginning_backslash(self) -> None:
-        source, expected = read_data("beginning_backslash")
+    def test_python39(self) -> None:
+        source, expected = read_data("python39")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
+        major, minor = sys.version_info[:2]
+        if major > 3 or (major == 3 and minor >= 9):
+            black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, DEFAULT_MODE)
 
     def test_tab_comment_indentation(self) -> None:
@@ -895,7 +552,7 @@ class BlackTestCase(unittest.TestCase):
         self.assertFormatEqual(contents_spc, fs(contents_tab))
 
     def test_report_verbose(self) -> None:
-        report = black.Report(verbose=True)
+        report = Report(verbose=True)
         out_lines = []
         err_lines = []
 
@@ -905,7 +562,7 @@ class BlackTestCase(unittest.TestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
+        with patch("black.output._out", out), patch("black.output._err", err):
             report.done(Path("f1"), black.Changed.NO)
             self.assertEqual(len(out_lines), 1)
             self.assertEqual(len(err_lines), 0)
@@ -997,7 +654,7 @@ class BlackTestCase(unittest.TestCase):
             )
 
     def test_report_quiet(self) -> None:
-        report = black.Report(quiet=True)
+        report = Report(quiet=True)
         out_lines = []
         err_lines = []
 
@@ -1007,7 +664,7 @@ class BlackTestCase(unittest.TestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
+        with patch("black.output._out", out), patch("black.output._err", err):
             report.done(Path("f1"), black.Changed.NO)
             self.assertEqual(len(out_lines), 0)
             self.assertEqual(len(err_lines), 0)
@@ -1101,7 +758,7 @@ class BlackTestCase(unittest.TestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
+        with patch("black.output._out", out), patch("black.output._err", err):
             report.done(Path("f1"), black.Changed.NO)
             self.assertEqual(len(out_lines), 0)
             self.assertEqual(len(err_lines), 0)
@@ -1212,6 +869,39 @@ class BlackTestCase(unittest.TestCase):
         black.lib2to3_parse(py3_only, {TargetVersion.PY36})
         black.lib2to3_parse(py3_only, {TargetVersion.PY27, TargetVersion.PY36})
 
+    def test_get_features_used_decorator(self) -> None:
+        # Test the feature detection of new decorator syntax
+        # since this makes some test cases of test_get_features_used()
+        # fails if it fails, this is tested first so that a useful case
+        # is identified
+        simples, relaxed = read_data("decorators")
+        # skip explanation comments at the top of the file
+        for simple_test in simples.split("##")[1:]:
+            node = black.lib2to3_parse(simple_test)
+            decorator = str(node.children[0].children[0]).strip()
+            self.assertNotIn(
+                Feature.RELAXED_DECORATORS,
+                black.get_features_used(node),
+                msg=(
+                    f"decorator '{decorator}' follows python<=3.8 syntax"
+                    "but is detected as 3.9+"
+                    # f"The full node is\n{node!r}"
+                ),
+            )
+        # skip the '# output' comment at the top of the output part
+        for relaxed_test in relaxed.split("##")[1:]:
+            node = black.lib2to3_parse(relaxed_test)
+            decorator = str(node.children[0].children[0]).strip()
+            self.assertIn(
+                Feature.RELAXED_DECORATORS,
+                black.get_features_used(node),
+                msg=(
+                    f"decorator '{decorator}' uses python3.9+ syntax"
+                    "but is detected as python<=3.8"
+                    # f"The full node is\n{node!r}"
+                ),
+            )
+
     def test_get_features_used(self) -> None:
         node = black.lib2to3_parse("def f(*, arg): ...\n")
         self.assertEqual(black.get_features_used(node), set())
@@ -1285,8 +975,8 @@ class BlackTestCase(unittest.TestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
-            black.DebugVisitor.show(source)
+        with patch("black.debug.out", out):
+            DebugVisitor.show(source)
         actual = "\n".join(out_lines) + "\n"
         log_name = ""
         if expected != actual:
@@ -1334,7 +1024,7 @@ class BlackTestCase(unittest.TestCase):
         def err(msg: str, **kwargs: Any) -> None:
             err_lines.append(msg)
 
-        with patch("black.out", out), patch("black.err", err):
+        with patch("black.output._out", out), patch("black.output._err", err):
             with self.assertRaises(AssertionError):
                 self.assertFormatEqual("j = [1, 2, 3]", "j = [1, 2, 3,]")
 
@@ -1346,7 +1036,7 @@ class BlackTestCase(unittest.TestCase):
     def test_cache_broken_file(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace:
-            cache_file = black.get_cache_file(mode)
+            cache_file = get_cache_file(mode)
             with cache_file.open("w") as fobj:
                 fobj.write("this is not a pickle")
             self.assertEqual(black.read_cache(mode), {})
@@ -1355,7 +1045,7 @@ class BlackTestCase(unittest.TestCase):
                 fobj.write("print('hello')")
             self.invokeBlack([str(src)])
             cache = black.read_cache(mode)
-            self.assertIn(src, cache)
+            self.assertIn(str(src), cache)
 
     def test_cache_single_file_already_cached(self) -> None:
         mode = DEFAULT_MODE
@@ -1387,8 +1077,8 @@ class BlackTestCase(unittest.TestCase):
             with two.open("r") as fobj:
                 self.assertEqual(fobj.read(), 'print("hello")\n')
             cache = black.read_cache(mode)
-            self.assertIn(one, cache)
-            self.assertIn(two, cache)
+            self.assertIn(str(one), cache)
+            self.assertIn(str(two), cache)
 
     def test_no_cache_when_writeback_diff(self) -> None:
         mode = DEFAULT_MODE
@@ -1400,7 +1090,7 @@ class BlackTestCase(unittest.TestCase):
                 "black.write_cache"
             ) as write_cache:
                 self.invokeBlack([str(src), "--diff"])
-                cache_file = black.get_cache_file(mode)
+                cache_file = get_cache_file(mode)
                 self.assertFalse(cache_file.exists())
                 write_cache.assert_not_called()
                 read_cache.assert_not_called()
@@ -1415,7 +1105,7 @@ class BlackTestCase(unittest.TestCase):
                 "black.write_cache"
             ) as write_cache:
                 self.invokeBlack([str(src), "--diff", "--color"])
-                cache_file = black.get_cache_file(mode)
+                cache_file = get_cache_file(mode)
                 self.assertFalse(cache_file.exists())
                 write_cache.assert_not_called()
                 read_cache.assert_not_called()
@@ -1453,7 +1143,7 @@ class BlackTestCase(unittest.TestCase):
                 black.main, ["-"], input=BytesIO(b"print('hello')")
             )
             self.assertEqual(result.exit_code, 0)
-            cache_file = black.get_cache_file(mode)
+            cache_file = get_cache_file(mode)
             self.assertFalse(cache_file.exists())
 
     def test_read_cache_no_cachefile(self) -> None:
@@ -1468,8 +1158,8 @@ class BlackTestCase(unittest.TestCase):
             src.touch()
             black.write_cache({}, [src], mode)
             cache = black.read_cache(mode)
-            self.assertIn(src, cache)
-            self.assertEqual(cache[src], black.get_cache_info(src))
+            self.assertIn(str(src), cache)
+            self.assertEqual(cache[str(src)], black.get_cache_info(src))
 
     def test_filter_cached(self) -> None:
         with TemporaryDirectory() as workspace:
@@ -1480,7 +1170,10 @@ class BlackTestCase(unittest.TestCase):
             uncached.touch()
             cached.touch()
             cached_but_changed.touch()
-            cache = {cached: black.get_cache_info(cached), cached_but_changed: (0.0, 0)}
+            cache = {
+                str(cached): black.get_cache_info(cached),
+                str(cached_but_changed): (0.0, 0),
+            }
             todo, done = black.filter_cached(
                 cache, {uncached, cached, cached_but_changed}
             )
@@ -1508,8 +1201,8 @@ class BlackTestCase(unittest.TestCase):
                 fobj.write('print("hello")\n')
             self.invokeBlack([str(workspace)], exit_code=123)
             cache = black.read_cache(mode)
-            self.assertNotIn(failing, cache)
-            self.assertIn(clean, cache)
+            self.assertNotIn(str(failing), cache)
+            self.assertIn(str(clean), cache)
 
     def test_write_cache_write_fail(self) -> None:
         mode = DEFAULT_MODE
@@ -1562,19 +1255,11 @@ class BlackTestCase(unittest.TestCase):
             path.touch()
             black.write_cache({}, [path], mode)
             one = black.read_cache(mode)
-            self.assertIn(path, one)
+            self.assertIn(str(path), one)
             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)
+            self.assertNotIn(str(path), two)
 
     def test_single_file_force_pyi(self) -> None:
-        reg_mode = DEFAULT_MODE
         pyi_mode = replace(DEFAULT_MODE, is_pyi=True)
         contents, expected = read_data("force_pyi")
         with cache_dir() as workspace:
@@ -1586,10 +1271,12 @@ class BlackTestCase(unittest.TestCase):
                 actual = fh.read()
             # verify cache with --pyi is separate
             pyi_cache = black.read_cache(pyi_mode)
-            self.assertIn(path, pyi_cache)
-            normal_cache = black.read_cache(reg_mode)
-            self.assertNotIn(path, normal_cache)
-        self.assertEqual(actual, expected)
+            self.assertIn(str(path), pyi_cache)
+            normal_cache = black.read_cache(DEFAULT_MODE)
+            self.assertNotIn(str(path), normal_cache)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(contents, actual)
+        black.assert_stable(contents, actual, pyi_mode)
 
     @event_loop()
     def test_multi_file_force_pyi(self) -> None:
@@ -1613,8 +1300,8 @@ class BlackTestCase(unittest.TestCase):
             pyi_cache = black.read_cache(pyi_mode)
             normal_cache = black.read_cache(reg_mode)
             for path in paths:
-                self.assertIn(path, pyi_cache)
-                self.assertNotIn(path, normal_cache)
+                self.assertIn(str(path), pyi_cache)
+                self.assertNotIn(str(path), normal_cache)
 
     def test_pipe_force_pyi(self) -> None:
         source, expected = read_data("force_pyi")
@@ -1627,7 +1314,7 @@ class BlackTestCase(unittest.TestCase):
 
     def test_single_file_force_py36(self) -> None:
         reg_mode = DEFAULT_MODE
-        py36_mode = replace(DEFAULT_MODE, target_versions=black.PY36_VERSIONS)
+        py36_mode = replace(DEFAULT_MODE, target_versions=PY36_VERSIONS)
         source, expected = read_data("force_py36")
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()
@@ -1638,15 +1325,15 @@ class BlackTestCase(unittest.TestCase):
                 actual = fh.read()
             # verify cache with --target-version is separate
             py36_cache = black.read_cache(py36_mode)
-            self.assertIn(path, py36_cache)
+            self.assertIn(str(path), py36_cache)
             normal_cache = black.read_cache(reg_mode)
-            self.assertNotIn(path, normal_cache)
+            self.assertNotIn(str(path), normal_cache)
         self.assertEqual(actual, expected)
 
     @event_loop()
     def test_multi_file_force_py36(self) -> None:
         reg_mode = DEFAULT_MODE
-        py36_mode = replace(DEFAULT_MODE, target_versions=black.PY36_VERSIONS)
+        py36_mode = replace(DEFAULT_MODE, target_versions=PY36_VERSIONS)
         source, expected = read_data("force_py36")
         with cache_dir() as workspace:
             paths = [
@@ -1665,15 +1352,8 @@ class BlackTestCase(unittest.TestCase):
             pyi_cache = black.read_cache(py36_mode)
             normal_cache = black.read_cache(reg_mode)
             for path in paths:
-                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)
+                self.assertIn(str(path), pyi_cache)
+                self.assertNotIn(str(path), normal_cache)
 
     def test_pipe_force_py36(self) -> None:
         source, expected = read_data("force_py36")
@@ -1700,7 +1380,42 @@ class BlackTestCase(unittest.TestCase):
         this_abs = THIS_DIR.resolve()
         sources.extend(
             black.gen_python_files(
-                path.iterdir(), this_abs, include, exclude, None, report, gitignore
+                path.iterdir(),
+                this_abs,
+                include,
+                exclude,
+                None,
+                None,
+                report,
+                gitignore,
+                verbose=False,
+                quiet=False,
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    def test_gitignore_used_as_default(self) -> None:
+        path = Path(THIS_DIR / "data" / "include_exclude_tests")
+        include = re.compile(r"\.pyi?$")
+        extend_exclude = re.compile(r"/exclude/")
+        src = str(path / "b/")
+        report = black.Report()
+        expected: List[Path] = [
+            path / "b/.definitely_exclude/a.py",
+            path / "b/.definitely_exclude/a.pyi",
+        ]
+        sources = list(
+            black.get_sources(
+                ctx=FakeContext(),
+                src=(src,),
+                quiet=True,
+                verbose=False,
+                include=include,
+                exclude=None,
+                extend_exclude=extend_exclude,
+                force_exclude=None,
+                report=report,
+                stdin_filename=None,
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
@@ -1722,14 +1437,270 @@ class BlackTestCase(unittest.TestCase):
                 src=(src,),
                 quiet=True,
                 verbose=False,
-                include=include,
-                exclude=exclude,
+                include=re.compile(include),
+                exclude=re.compile(exclude),
+                extend_exclude=None,
+                force_exclude=None,
+                report=report,
+                stdin_filename=None,
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    def test_get_sources_with_stdin(self) -> None:
+        include = ""
+        exclude = r"/exclude/|a\.py"
+        src = "-"
+        report = black.Report()
+        expected = [Path("-")]
+        sources = list(
+            black.get_sources(
+                ctx=FakeContext(),
+                src=(src,),
+                quiet=True,
+                verbose=False,
+                include=re.compile(include),
+                exclude=re.compile(exclude),
+                extend_exclude=None,
+                force_exclude=None,
+                report=report,
+                stdin_filename=None,
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    def test_get_sources_with_stdin_filename(self) -> None:
+        include = ""
+        exclude = r"/exclude/|a\.py"
+        src = "-"
+        report = black.Report()
+        stdin_filename = str(THIS_DIR / "data/collections.py")
+        expected = [Path(f"__BLACK_STDIN_FILENAME__{stdin_filename}")]
+        sources = list(
+            black.get_sources(
+                ctx=FakeContext(),
+                src=(src,),
+                quiet=True,
+                verbose=False,
+                include=re.compile(include),
+                exclude=re.compile(exclude),
+                extend_exclude=None,
+                force_exclude=None,
+                report=report,
+                stdin_filename=stdin_filename,
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    def test_get_sources_with_stdin_filename_and_exclude(self) -> None:
+        # Exclude shouldn't exclude stdin_filename since it is mimicking the
+        # file being passed directly. This is the same as
+        # test_exclude_for_issue_1572
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        include = ""
+        exclude = r"/exclude/|a\.py"
+        src = "-"
+        report = black.Report()
+        stdin_filename = str(path / "b/exclude/a.py")
+        expected = [Path(f"__BLACK_STDIN_FILENAME__{stdin_filename}")]
+        sources = list(
+            black.get_sources(
+                ctx=FakeContext(),
+                src=(src,),
+                quiet=True,
+                verbose=False,
+                include=re.compile(include),
+                exclude=re.compile(exclude),
+                extend_exclude=None,
+                force_exclude=None,
+                report=report,
+                stdin_filename=stdin_filename,
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    def test_get_sources_with_stdin_filename_and_extend_exclude(self) -> None:
+        # Extend exclude shouldn't exclude stdin_filename since it is mimicking the
+        # file being passed directly. This is the same as
+        # test_exclude_for_issue_1572
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        include = ""
+        extend_exclude = r"/exclude/|a\.py"
+        src = "-"
+        report = black.Report()
+        stdin_filename = str(path / "b/exclude/a.py")
+        expected = [Path(f"__BLACK_STDIN_FILENAME__{stdin_filename}")]
+        sources = list(
+            black.get_sources(
+                ctx=FakeContext(),
+                src=(src,),
+                quiet=True,
+                verbose=False,
+                include=re.compile(include),
+                exclude=re.compile(""),
+                extend_exclude=re.compile(extend_exclude),
                 force_exclude=None,
                 report=report,
+                stdin_filename=stdin_filename,
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
 
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    def test_get_sources_with_stdin_filename_and_force_exclude(self) -> None:
+        # Force exclude should exclude the file when passing it through
+        # stdin_filename
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        include = ""
+        force_exclude = r"/exclude/|a\.py"
+        src = "-"
+        report = black.Report()
+        stdin_filename = str(path / "b/exclude/a.py")
+        sources = list(
+            black.get_sources(
+                ctx=FakeContext(),
+                src=(src,),
+                quiet=True,
+                verbose=False,
+                include=re.compile(include),
+                exclude=re.compile(""),
+                extend_exclude=None,
+                force_exclude=re.compile(force_exclude),
+                report=report,
+                stdin_filename=stdin_filename,
+            )
+        )
+        self.assertEqual([], sorted(sources))
+
+    def test_reformat_one_with_stdin(self) -> None:
+        with patch(
+            "black.format_stdin_to_stdout",
+            return_value=lambda *args, **kwargs: black.Changed.YES,
+        ) as fsts:
+            report = MagicMock()
+            path = Path("-")
+            black.reformat_one(
+                path,
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=DEFAULT_MODE,
+                report=report,
+            )
+            fsts.assert_called_once()
+            report.done.assert_called_with(path, black.Changed.YES)
+
+    def test_reformat_one_with_stdin_filename(self) -> None:
+        with patch(
+            "black.format_stdin_to_stdout",
+            return_value=lambda *args, **kwargs: black.Changed.YES,
+        ) as fsts:
+            report = MagicMock()
+            p = "foo.py"
+            path = Path(f"__BLACK_STDIN_FILENAME__{p}")
+            expected = Path(p)
+            black.reformat_one(
+                path,
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=DEFAULT_MODE,
+                report=report,
+            )
+            fsts.assert_called_once_with(
+                fast=True, write_back=black.WriteBack.YES, mode=DEFAULT_MODE
+            )
+            # __BLACK_STDIN_FILENAME__ should have been stripped
+            report.done.assert_called_with(expected, black.Changed.YES)
+
+    def test_reformat_one_with_stdin_filename_pyi(self) -> None:
+        with patch(
+            "black.format_stdin_to_stdout",
+            return_value=lambda *args, **kwargs: black.Changed.YES,
+        ) as fsts:
+            report = MagicMock()
+            p = "foo.pyi"
+            path = Path(f"__BLACK_STDIN_FILENAME__{p}")
+            expected = Path(p)
+            black.reformat_one(
+                path,
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=DEFAULT_MODE,
+                report=report,
+            )
+            fsts.assert_called_once_with(
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=replace(DEFAULT_MODE, is_pyi=True),
+            )
+            # __BLACK_STDIN_FILENAME__ should have been stripped
+            report.done.assert_called_with(expected, black.Changed.YES)
+
+    def test_reformat_one_with_stdin_filename_ipynb(self) -> None:
+        with patch(
+            "black.format_stdin_to_stdout",
+            return_value=lambda *args, **kwargs: black.Changed.YES,
+        ) as fsts:
+            report = MagicMock()
+            p = "foo.ipynb"
+            path = Path(f"__BLACK_STDIN_FILENAME__{p}")
+            expected = Path(p)
+            black.reformat_one(
+                path,
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=DEFAULT_MODE,
+                report=report,
+            )
+            fsts.assert_called_once_with(
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=replace(DEFAULT_MODE, is_ipynb=True),
+            )
+            # __BLACK_STDIN_FILENAME__ should have been stripped
+            report.done.assert_called_with(expected, black.Changed.YES)
+
+    def test_reformat_one_with_stdin_and_existing_path(self) -> None:
+        with patch(
+            "black.format_stdin_to_stdout",
+            return_value=lambda *args, **kwargs: black.Changed.YES,
+        ) as fsts:
+            report = MagicMock()
+            # Even with an existing file, since we are forcing stdin, black
+            # should output to stdout and not modify the file inplace
+            p = Path(str(THIS_DIR / "data/collections.py"))
+            # Make sure is_file actually returns True
+            self.assertTrue(p.is_file())
+            path = Path(f"__BLACK_STDIN_FILENAME__{p}")
+            expected = Path(p)
+            black.reformat_one(
+                path,
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=DEFAULT_MODE,
+                report=report,
+            )
+            fsts.assert_called_once()
+            # __BLACK_STDIN_FILENAME__ should have been stripped
+            report.done.assert_called_with(expected, black.Changed.YES)
+
+    def test_reformat_one_with_stdin_empty(self) -> None:
+        output = io.StringIO()
+        with patch("io.TextIOWrapper", lambda *args, **kwargs: output):
+            try:
+                black.format_stdin_to_stdout(
+                    fast=True,
+                    content="",
+                    write_back=black.WriteBack.YES,
+                    mode=DEFAULT_MODE,
+                )
+            except io.UnsupportedOperation:
+                pass  # StringIO does not support detach
+            assert output.getvalue() == ""
+
     def test_gitignore_exclude(self) -> None:
         path = THIS_DIR / "data" / "include_exclude_tests"
         include = re.compile(r"\.pyi?$")
@@ -1746,11 +1717,73 @@ class BlackTestCase(unittest.TestCase):
         this_abs = THIS_DIR.resolve()
         sources.extend(
             black.gen_python_files(
-                path.iterdir(), this_abs, include, exclude, None, report, gitignore
+                path.iterdir(),
+                this_abs,
+                include,
+                exclude,
+                None,
+                None,
+                report,
+                gitignore,
+                verbose=False,
+                quiet=False,
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    def test_nested_gitignore(self) -> None:
+        path = Path(THIS_DIR / "data" / "nested_gitignore_tests")
+        include = re.compile(r"\.pyi?$")
+        exclude = re.compile(r"")
+        root_gitignore = black.files.get_gitignore(path)
+        report = black.Report()
+        expected: List[Path] = [
+            Path(path / "x.py"),
+            Path(path / "root/b.py"),
+            Path(path / "root/c.py"),
+            Path(path / "root/child/c.py"),
+        ]
+        this_abs = THIS_DIR.resolve()
+        sources = list(
+            black.gen_python_files(
+                path.iterdir(),
+                this_abs,
+                include,
+                exclude,
+                None,
+                None,
+                report,
+                root_gitignore,
+                verbose=False,
+                quiet=False,
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
 
+    def test_invalid_gitignore(self) -> None:
+        path = THIS_DIR / "data" / "invalid_gitignore_tests"
+        empty_config = path / "pyproject.toml"
+        result = BlackRunner().invoke(
+            black.main, ["--verbose", "--config", str(empty_config), str(path)]
+        )
+        assert result.exit_code == 1
+        assert result.stderr_bytes is not None
+
+        gitignore = path / ".gitignore"
+        assert f"Could not parse {gitignore}" in result.stderr_bytes.decode()
+
+    def test_invalid_nested_gitignore(self) -> None:
+        path = THIS_DIR / "data" / "invalid_nested_gitignore_tests"
+        empty_config = path / "pyproject.toml"
+        result = BlackRunner().invoke(
+            black.main, ["--verbose", "--config", str(empty_config), str(path)]
+        )
+        assert result.exit_code == 1
+        assert result.stderr_bytes is not None
+
+        gitignore = path / "a" / ".gitignore"
+        assert f"Could not parse {gitignore}" in result.stderr_bytes.decode()
+
     def test_empty_include(self) -> None:
         path = THIS_DIR / "data" / "include_exclude_tests"
         report = black.Report()
@@ -1767,6 +1800,8 @@ class BlackTestCase(unittest.TestCase):
             Path(path / "b/.definitely_exclude/a.pie"),
             Path(path / "b/.definitely_exclude/a.py"),
             Path(path / "b/.definitely_exclude/a.pyi"),
+            Path(path / ".gitignore"),
+            Path(path / "pyproject.toml"),
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(
@@ -1776,25 +1811,23 @@ class BlackTestCase(unittest.TestCase):
                 empty,
                 re.compile(black.DEFAULT_EXCLUDES),
                 None,
+                None,
                 report,
                 gitignore,
+                verbose=False,
+                quiet=False,
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
 
-    def test_empty_exclude(self) -> None:
+    def test_extend_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 = [
-            Path(path / "b/dont_exclude/a.py"),
-            Path(path / "b/dont_exclude/a.pyi"),
             Path(path / "b/exclude/a.py"),
-            Path(path / "b/exclude/a.pyi"),
-            Path(path / "b/.definitely_exclude/a.py"),
-            Path(path / "b/.definitely_exclude/a.pyi"),
+            Path(path / "b/dont_exclude/a.py"),
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(
@@ -1802,18 +1835,31 @@ class BlackTestCase(unittest.TestCase):
                 path.iterdir(),
                 this_abs,
                 re.compile(black.DEFAULT_INCLUDES),
-                empty,
+                re.compile(r"\.pyi$"),
+                re.compile(r"\.definitely_exclude"),
                 None,
                 report,
                 gitignore,
+                verbose=False,
+                quiet=False,
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
 
-    def test_invalid_include_exclude(self) -> None:
-        for option in ["--include", "--exclude"]:
+    def test_invalid_cli_regex(self) -> None:
+        for option in ["--include", "--exclude", "--extend-exclude", "--force-exclude"]:
             self.invokeBlack(["-", option, "**()(!!*)"], exit_code=2)
 
+    def test_required_version_matches_version(self) -> None:
+        self.invokeBlack(
+            ["--required-version", black.__version__], exit_code=0, ignore_config=True
+        )
+
+    def test_required_version_does_not_match_version(self) -> None:
+        self.invokeBlack(
+            ["--required-version", "20.99b"], exit_code=1, ignore_config=True
+        )
+
     def test_preserves_line_endings(self) -> None:
         with TemporaryDirectory() as workspace:
             test_file = Path(workspace) / "test.py"
@@ -1834,7 +1880,7 @@ class BlackTestCase(unittest.TestCase):
                 black.main, ["-", "--fast"], input=BytesIO(contents.encode("utf8"))
             )
             self.assertEqual(result.exit_code, 0)
-            output = runner.stdout_bytes
+            output = result.stdout_bytes
             self.assertIn(nl.encode("utf8"), output)
             if nl == "\n":
                 self.assertNotIn(b"\r\n", output)
@@ -1860,7 +1906,16 @@ class BlackTestCase(unittest.TestCase):
         try:
             list(
                 black.gen_python_files(
-                    path.iterdir(), root, include, exclude, None, report, gitignore
+                    path.iterdir(),
+                    root,
+                    include,
+                    exclude,
+                    None,
+                    None,
+                    report,
+                    gitignore,
+                    verbose=False,
+                    quiet=False,
                 )
             )
         except ValueError as ve:
@@ -1874,7 +1929,16 @@ class BlackTestCase(unittest.TestCase):
         with self.assertRaises(ValueError):
             list(
                 black.gen_python_files(
-                    path.iterdir(), root, include, exclude, None, report, gitignore
+                    path.iterdir(),
+                    root,
+                    include,
+                    exclude,
+                    None,
+                    None,
+                    report,
+                    gitignore,
+                    verbose=False,
+                    quiet=False,
                 )
             )
         path.iterdir.assert_called()
@@ -1886,7 +1950,7 @@ class BlackTestCase(unittest.TestCase):
 
     def test_shhh_click(self) -> None:
         try:
-            from click import _unicodefun  # type: ignore
+            from click import _unicodefun
         except ModuleNotFoundError:
             self.skipTest("Incompatible Click version")
         if not hasattr(_unicodefun, "_verify_python3_env"):
@@ -1895,14 +1959,14 @@ class BlackTestCase(unittest.TestCase):
         with patch("locale.getpreferredencoding") as gpe:
             gpe.return_value = "ASCII"
             with self.assertRaises(RuntimeError):
-                _unicodefun._verify_python3_env()
+                _unicodefun._verify_python3_env()  # type: ignore
         # Now, let's silence Click...
         black.patch_click()
         # ...and confirm it's silent.
         with patch("locale.getpreferredencoding") as gpe:
             gpe.return_value = "ASCII"
             try:
-                _unicodefun._verify_python3_env()
+                _unicodefun._verify_python3_env()  # type: ignore
             except RuntimeError as re:
                 self.fail(f"`patch_click()` failed, exception still raised: {re}")
 
@@ -1919,15 +1983,7 @@ class BlackTestCase(unittest.TestCase):
             critical=fail,
             log=fail,
         ):
-            ff(THIS_FILE)
-
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    def test_blackd_main(self) -> None:
-        with patch("blackd.web.run_app"):
-            result = CliRunner().invoke(blackd.main, [])
-            if result.exception is not None:
-                raise result.exception
-            self.assertEqual(result.exit_code, 0)
+            ff(THIS_DIR / "util.py")
 
     def test_invalid_config_return_code(self) -> None:
         tmp_file = Path(black.dump_to_file())
@@ -1987,190 +2043,231 @@ class BlackTestCase(unittest.TestCase):
             self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
             self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
 
+    @patch(
+        "black.files.find_user_pyproject_toml",
+        black.files.find_user_pyproject_toml.__wrapped__,
+    )
+    def test_find_user_pyproject_toml_linux(self) -> None:
+        if system() == "Windows":
+            return
+
+        # Test if XDG_CONFIG_HOME is checked
+        with TemporaryDirectory() as workspace:
+            tmp_user_config = Path(workspace) / "black"
+            with patch.dict("os.environ", {"XDG_CONFIG_HOME": workspace}):
+                self.assertEqual(
+                    black.files.find_user_pyproject_toml(), tmp_user_config.resolve()
+                )
+
+        # Test fallback for XDG_CONFIG_HOME
+        with patch.dict("os.environ"):
+            os.environ.pop("XDG_CONFIG_HOME", None)
+            fallback_user_config = Path("~/.config").expanduser() / "black"
+            self.assertEqual(
+                black.files.find_user_pyproject_toml(), fallback_user_config.resolve()
+            )
+
+    def test_find_user_pyproject_toml_windows(self) -> None:
+        if system() != "Windows":
+            return
+
+        user_config_path = Path.home() / ".black"
+        self.assertEqual(
+            black.files.find_user_pyproject_toml(), user_config_path.resolve()
+        )
+
     def test_bpo_33660_workaround(self) -> None:
         if system() == "Windows":
             return
 
         # https://bugs.python.org/issue33660
-
-        old_cwd = Path.cwd()
-        try:
-            root = Path("/")
-            os.chdir(str(root))
+        root = Path("/")
+        with change_directory(root):
             path = Path("workspace") / "project"
             report = black.Report(verbose=True)
             normalized_path = black.normalize_path_maybe_ignore(path, root, report)
             self.assertEqual(normalized_path, "workspace/project")
-        finally:
-            os.chdir(str(old_cwd))
-
-
-class BlackDTestCase(AioHTTPTestCase):
-    async def get_application(self) -> web.Application:
-        return blackd.make_app()
-
-    # TODO: remove these decorators once the below is released
-    # https://github.com/aio-libs/aiohttp/pull/3727
-    @skip_if_exception("ClientOSError")
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    @unittest_run_loop
-    async def test_blackd_request_needs_formatting(self) -> None:
-        response = await self.client.post("/", data=b"print('hello world')")
-        self.assertEqual(response.status, 200)
-        self.assertEqual(response.charset, "utf8")
-        self.assertEqual(await response.read(), b'print("hello world")\n')
-
-    @skip_if_exception("ClientOSError")
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    @unittest_run_loop
-    async def test_blackd_request_no_change(self) -> None:
-        response = await self.client.post("/", data=b'print("hello world")\n')
-        self.assertEqual(response.status, 204)
-        self.assertEqual(await response.read(), b"")
-
-    @skip_if_exception("ClientOSError")
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    @unittest_run_loop
-    async def test_blackd_request_syntax_error(self) -> None:
-        response = await self.client.post("/", data=b"what even ( is")
-        self.assertEqual(response.status, 400)
-        content = await response.text()
-        self.assertTrue(
-            content.startswith("Cannot parse"),
-            msg=f"Expected error to start with 'Cannot parse', got {repr(content)}",
-        )
 
-    @skip_if_exception("ClientOSError")
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    @unittest_run_loop
-    async def test_blackd_unsupported_version(self) -> None:
-        response = await self.client.post(
-            "/", data=b"what", headers={blackd.PROTOCOL_VERSION_HEADER: "2"}
-        )
-        self.assertEqual(response.status, 501)
-
-    @skip_if_exception("ClientOSError")
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    @unittest_run_loop
-    async def test_blackd_supported_version(self) -> None:
-        response = await self.client.post(
-            "/", data=b"what", headers={blackd.PROTOCOL_VERSION_HEADER: "1"}
-        )
-        self.assertEqual(response.status, 200)
-
-    @skip_if_exception("ClientOSError")
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    @unittest_run_loop
-    async def test_blackd_invalid_python_variant(self) -> None:
-        async def check(header_value: str, expected_status: int = 400) -> None:
-            response = await self.client.post(
-                "/", data=b"what", headers={blackd.PYTHON_VARIANT_HEADER: header_value}
-            )
-            self.assertEqual(response.status, expected_status)
-
-        await check("lol")
-        await check("ruby3.5")
-        await check("pyi3.6")
-        await check("py1.5")
-        await check("2.8")
-        await check("py2.8")
-        await check("3.0")
-        await check("pypy3.0")
-        await check("jython3.4")
-
-    @skip_if_exception("ClientOSError")
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    @unittest_run_loop
-    async def test_blackd_pyi(self) -> None:
-        source, expected = read_data("stub.pyi")
-        response = await self.client.post(
-            "/", data=source, headers={blackd.PYTHON_VARIANT_HEADER: "pyi"}
-        )
-        self.assertEqual(response.status, 200)
-        self.assertEqual(await response.text(), expected)
+    def test_newline_comment_interaction(self) -> None:
+        source = "class A:\\\r\n# type: ignore\n pass\n"
+        output = black.format_str(source, mode=DEFAULT_MODE)
+        black.assert_stable(source, output, mode=DEFAULT_MODE)
 
-    @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"
-        )
+    def test_bpo_2142_workaround(self) -> None:
 
-        source, _ = read_data("blackd_diff.py")
-        expected, _ = read_data("blackd_diff.diff")
+        # https://bugs.python.org/issue2142
 
-        response = await self.client.post(
-            "/", data=source, headers={blackd.DIFF_HEADER: "true"}
+        source, _ = read_data("missing_final_newline.py")
+        # read_data adds a trailing newline
+        source = source.rstrip()
+        expected, _ = read_data("missing_final_newline.diff")
+        tmp_file = Path(black.dump_to_file(source, ensure_final_newline=False))
+        diff_header = re.compile(
+            rf"{re.escape(str(tmp_file))}\t\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"
         )
-        self.assertEqual(response.status, 200)
-
-        actual = await response.text()
+        try:
+            result = BlackRunner().invoke(black.main, ["--diff", str(tmp_file)])
+            self.assertEqual(result.exit_code, 0)
+        finally:
+            os.unlink(tmp_file)
+        actual = result.output
         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
-    async def test_blackd_python_variant(self) -> None:
-        code = (
-            "def f(\n"
-            "    and_has_a_bunch_of,\n"
-            "    very_long_arguments_too,\n"
-            "    and_lots_of_them_as_well_lol,\n"
-            "    **and_very_long_keyword_arguments\n"
-            "):\n"
-            "    pass\n"
+    @pytest.mark.python2
+    def test_docstring_reformat_for_py27(self) -> None:
+        """
+        Check that stripping trailing whitespace from Python 2 docstrings
+        doesn't trigger a "not equivalent to source" error
+        """
+        source = (
+            b'def foo():\r\n    """Testing\r\n    Testing """\r\n    print "Foo"\r\n'
         )
+        expected = 'def foo():\n    """Testing\n    Testing"""\n    print "Foo"\n'
 
-        async def check(header_value: str, expected_status: int) -> None:
-            response = await self.client.post(
-                "/", data=code, headers={blackd.PYTHON_VARIANT_HEADER: header_value}
-            )
-            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("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("py34,py36", 204)
-        await check("34", 204)
-
-    @skip_if_exception("ClientOSError")
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    @unittest_run_loop
-    async def test_blackd_line_length(self) -> None:
-        response = await self.client.post(
-            "/", data=b'print("hello")\n', headers={blackd.LINE_LENGTH_HEADER: "7"}
-        )
-        self.assertEqual(response.status, 200)
-
-    @skip_if_exception("ClientOSError")
-    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
-    @unittest_run_loop
-    async def test_blackd_invalid_line_length(self) -> None:
-        response = await self.client.post(
-            "/", data=b'print("hello")\n', headers={blackd.LINE_LENGTH_HEADER: "NaN"}
+        result = CliRunner().invoke(
+            black.main,
+            ["-", "-q", "--target-version=py27"],
+            input=BytesIO(source),
         )
-        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))
+
+        self.assertEqual(result.exit_code, 0)
+        actual = result.output
+        self.assertFormatEqual(actual, expected)
+
+    @staticmethod
+    def compare_results(
+        result: click.testing.Result, expected_value: str, expected_exit_code: int
+    ) -> None:
+        """Helper method to test the value and exit code of a click Result."""
+        assert (
+            result.output == expected_value
+        ), "The output did not match the expected value."
+        assert result.exit_code == expected_exit_code, "The exit code is incorrect."
+
+    def test_code_option(self) -> None:
+        """Test the code option with no changes."""
+        code = 'print("Hello world")\n'
+        args = ["--code", code]
+        result = CliRunner().invoke(black.main, args)
+
+        self.compare_results(result, code, 0)
+
+    def test_code_option_changed(self) -> None:
+        """Test the code option when changes are required."""
+        code = "print('hello world')"
+        formatted = black.format_str(code, mode=DEFAULT_MODE)
+
+        args = ["--code", code]
+        result = CliRunner().invoke(black.main, args)
+
+        self.compare_results(result, formatted, 0)
+
+    def test_code_option_check(self) -> None:
+        """Test the code option when check is passed."""
+        args = ["--check", "--code", 'print("Hello world")\n']
+        result = CliRunner().invoke(black.main, args)
+        self.compare_results(result, "", 0)
+
+    def test_code_option_check_changed(self) -> None:
+        """Test the code option when changes are required, and check is passed."""
+        args = ["--check", "--code", "print('hello world')"]
+        result = CliRunner().invoke(black.main, args)
+        self.compare_results(result, "", 1)
+
+    def test_code_option_diff(self) -> None:
+        """Test the code option when diff is passed."""
+        code = "print('hello world')"
+        formatted = black.format_str(code, mode=DEFAULT_MODE)
+        result_diff = diff(code, formatted, "STDIN", "STDOUT")
+
+        args = ["--diff", "--code", code]
+        result = CliRunner().invoke(black.main, args)
+
+        # Remove time from diff
+        output = DIFF_TIME.sub("", result.output)
+
+        assert output == result_diff, "The output did not match the expected value."
+        assert result.exit_code == 0, "The exit code is incorrect."
+
+    def test_code_option_color_diff(self) -> None:
+        """Test the code option when color and diff are passed."""
+        code = "print('hello world')"
+        formatted = black.format_str(code, mode=DEFAULT_MODE)
+
+        result_diff = diff(code, formatted, "STDIN", "STDOUT")
+        result_diff = color_diff(result_diff)
+
+        args = ["--diff", "--color", "--code", code]
+        result = CliRunner().invoke(black.main, args)
+
+        # Remove time from diff
+        output = DIFF_TIME.sub("", result.output)
+
+        assert output == result_diff, "The output did not match the expected value."
+        assert result.exit_code == 0, "The exit code is incorrect."
+
+    def test_code_option_safe(self) -> None:
+        """Test that the code option throws an error when the sanity checks fail."""
+        # Patch black.assert_equivalent to ensure the sanity checks fail
+        with patch.object(black, "assert_equivalent", side_effect=AssertionError):
+            code = 'print("Hello world")'
+            error_msg = f"{code}\nerror: cannot format <string>: \n"
+
+            args = ["--safe", "--code", code]
+            result = CliRunner().invoke(black.main, args)
+
+            self.compare_results(result, error_msg, 123)
+
+    def test_code_option_fast(self) -> None:
+        """Test that the code option ignores errors when the sanity checks fail."""
+        # Patch black.assert_equivalent to ensure the sanity checks fail
+        with patch.object(black, "assert_equivalent", side_effect=AssertionError):
+            code = 'print("Hello world")'
+            formatted = black.format_str(code, mode=DEFAULT_MODE)
+
+            args = ["--fast", "--code", code]
+            result = CliRunner().invoke(black.main, args)
+
+            self.compare_results(result, formatted, 0)
+
+    def test_code_option_config(self) -> None:
+        """
+        Test that the code option finds the pyproject.toml in the current directory.
+        """
+        with patch.object(black, "parse_pyproject_toml", return_value={}) as parse:
+            args = ["--code", "print"]
+            CliRunner().invoke(black.main, args)
+
+            pyproject_path = Path(Path().cwd(), "pyproject.toml").resolve()
+            assert (
+                len(parse.mock_calls) >= 1
+            ), "Expected config parse to be called with the current directory."
+
+            _, call_args, _ = parse.mock_calls[0]
+            assert (
+                call_args[0].lower() == str(pyproject_path).lower()
+            ), "Incorrect config loaded."
+
+    def test_code_option_parent_config(self) -> None:
+        """
+        Test that the code option finds the pyproject.toml in the parent directory.
+        """
+        with patch.object(black, "parse_pyproject_toml", return_value={}) as parse:
+            with change_directory(Path("tests")):
+                args = ["--code", "print"]
+                CliRunner().invoke(black.main, args)
+
+                pyproject_path = Path(Path().cwd().parent, "pyproject.toml").resolve()
+                assert (
+                    len(parse.mock_calls) >= 1
+                ), "Expected config parse to be called with the current directory."
+
+                _, call_args, _ = parse.mock_calls[0]
+                assert (
+                    call_args[0].lower() == str(pyproject_path).lower()
+                ), "Incorrect config loaded."
 
 
 with open(black.__file__, "r", encoding="utf-8") as _bf: