]> git.madduck.net Git - etc/vim.git/blobdiff - tests/test_black.py

madduck's git repository

Every one of the projects in this repository is available at the canonical URL git://git.madduck.net/madduck/pub/<projectpath> — see each project's metadata for the exact URL.

All patches and comments are welcome. Please squash your changes to logical commits before using git-format-patch and git-send-email to patches@git.madduck.net. If you'd read over the Git project's submission guidelines and adhered to them, I'd be especially grateful.

SSH access, as well as push access can be individually arranged.

If you use my repositories frequently, consider adding the following snippet to ~/.gitconfig and using the third clone URL listed for each project:

[url "git://git.madduck.net/madduck/"]
  insteadOf = madduck:

add change log entry
[etc/vim.git] / tests / test_black.py
index fc310690ccec649a339bad18b53e6d44ccd335c7..4e0a03a48be3ed9a6d8eae9e6453deb398138f13 100644 (file)
@@ -1,40 +1,67 @@
 #!/usr/bin/env python3
 import asyncio
+import logging
+from concurrent.futures import ThreadPoolExecutor
 from contextlib import contextmanager
-from functools import partial
-from io import StringIO
+from functools import partial, wraps
+from io import BytesIO, TextIOWrapper
 import os
 from pathlib import Path
+import re
 import sys
 from tempfile import TemporaryDirectory
-from typing import Any, List, Tuple, Iterator
+from typing import (
+    Any,
+    BinaryIO,
+    Callable,
+    Coroutine,
+    Generator,
+    List,
+    Tuple,
+    Iterator,
+    TypeVar,
+)
 import unittest
-from unittest.mock import patch
+from unittest.mock import patch, MagicMock
 
 from click import unstyle
 from click.testing import CliRunner
 
 import black
-
-ll = 88
-ff = partial(black.format_file_in_place, line_length=ll, fast=True)
-fs = partial(black.format_str, line_length=ll)
+from black import Feature, TargetVersion
+
+try:
+    import blackd
+    from aiohttp.test_utils import TestClient, TestServer
+except ImportError:
+    has_blackd_deps = False
+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())
 THIS_FILE = Path(__file__)
 THIS_DIR = THIS_FILE.parent
 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
+]
+T = TypeVar("T")
+R = TypeVar("R")
 
 
 def dump_to_stderr(*output: str) -> str:
     return "\n" + "\n".join(output) + "\n"
 
 
-def read_data(name: str) -> Tuple[str, str]:
+def read_data(name: str, data: bool = True) -> Tuple[str, str]:
     """read_data('test_name') -> 'input', 'output'"""
-    if not name.endswith((".py", ".out", ".diff")):
+    if not name.endswith((".py", ".pyi", ".out", ".diff")):
         name += ".py"
     _input: List[str] = []
     _output: List[str] = []
-    with open(THIS_DIR / name, "r", encoding="utf8") as test:
+    base_dir = THIS_DIR / "data" if data else THIS_DIR
+    with open(base_dir / name, "r", encoding="utf8") as test:
         lines = test.readlines()
     result = _input
     for line in lines:
@@ -56,8 +83,7 @@ def cache_dir(exists: bool = True) -> Iterator[Path]:
         cache_dir = Path(workspace)
         if not exists:
             cache_dir = cache_dir / "new"
-        cache_file = cache_dir / "cache.pkl"
-        with patch("black.CACHE_DIR", cache_dir), patch("black.CACHE_FILE", cache_file):
+        with patch("black.CACHE_DIR", cache_dir):
             yield cache_dir
 
 
@@ -76,6 +102,40 @@ def event_loop(close: bool) -> Iterator[None]:
             loop.close()
 
 
+def async_test(f: Callable[..., Coroutine[Any, None, R]]) -> Callable[..., None]:
+    @event_loop(close=True)
+    @wraps(f)
+    def wrapper(*args: Any, **kwargs: Any) -> None:
+        asyncio.get_event_loop().run_until_complete(f(*args, **kwargs))
+
+    return wrapper
+
+
+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"""
+
+    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
 
@@ -98,65 +158,94 @@ class BlackTestCase(unittest.TestCase):
                 black.err(str(ve))
         self.assertEqual(expected, actual)
 
+    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]
+        result = runner.invoke(black.main, args)
+        self.assertEqual(result.exit_code, exit_code, msg=runner.stderr_bytes.decode())
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_empty(self) -> None:
+        source = expected = ""
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, black.FileMode())
+
+    def test_empty_ff(self) -> None:
+        expected = ""
+        tmp_file = Path(black.dump_to_file())
+        try:
+            self.assertFalse(ff(tmp_file, write_back=black.WriteBack.YES))
+            with open(tmp_file, encoding="utf8") as f:
+                actual = f.read()
+        finally:
+            os.unlink(tmp_file)
+        self.assertFormatEqual(expected, actual)
+
     @patch("black.dump_to_file", dump_to_stderr)
     def test_self(self) -> None:
-        source, expected = read_data("test_black")
+        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, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
         self.assertFalse(ff(THIS_FILE))
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_black(self) -> None:
-        source, expected = read_data("../black")
+        source, expected = read_data("../black", data=False)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
         self.assertFalse(ff(THIS_DIR / ".." / "black.py"))
 
     def test_piping(self) -> None:
-        source, expected = read_data("../black")
-        hold_stdin, hold_stdout = sys.stdin, sys.stdout
-        try:
-            sys.stdin, sys.stdout = StringIO(source), StringIO()
-            sys.stdin.name = "<stdin>"
-            black.format_stdin_to_stdout(
-                line_length=ll, fast=True, write_back=black.WriteBack.YES
-            )
-            sys.stdout.seek(0)
-            actual = sys.stdout.read()
-        finally:
-            sys.stdin, sys.stdout = hold_stdin, hold_stdout
-        self.assertFormatEqual(expected, actual)
-        black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        source, expected = read_data("../black", data=False)
+        result = BlackRunner().invoke(
+            black.main,
+            ["-", "--fast", f"--line-length={black.DEFAULT_LINE_LENGTH}"],
+            input=BytesIO(source.encode("utf8")),
+        )
+        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())
 
     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"
+        )
         source, _ = read_data("expression.py")
         expected, _ = read_data("expression.diff")
-        hold_stdin, hold_stdout = sys.stdin, sys.stdout
-        try:
-            sys.stdin, sys.stdout = StringIO(source), StringIO()
-            sys.stdin.name = "<stdin>"
-            black.format_stdin_to_stdout(
-                line_length=ll, fast=True, write_back=black.WriteBack.DIFF
-            )
-            sys.stdout.seek(0)
-            actual = sys.stdout.read()
-        finally:
-            sys.stdin, sys.stdout = hold_stdin, hold_stdout
+        config = THIS_DIR / "data" / "empty_pyproject.toml"
+        args = [
+            "-",
+            "--fast",
+            f"--line-length={black.DEFAULT_LINE_LENGTH}",
+            "--diff",
+            f"--config={config}",
+        ]
+        result = BlackRunner().invoke(
+            black.main, args, input=BytesIO(source.encode("utf8"))
+        )
+        self.assertEqual(result.exit_code, 0)
+        actual = diff_header.sub("[Deterministic header]", result.output)
         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")
+        source, expected = read_data("../setup", data=False)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
         self.assertFalse(ff(THIS_DIR / ".." / "setup.py"))
 
     @patch("black.dump_to_file", dump_to_stderr)
@@ -165,7 +254,23 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
+
+    @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, 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, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_expression(self) -> None:
@@ -173,7 +278,24 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
+
+    @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())
+        if sys.version_info >= (3, 8):
+            black.assert_equivalent(source, actual)
+
+    def test_pep_572_version_detection(self) -> None:
+        source, _ = read_data("pep_572")
+        root = black.lib2to3_parse(source)
+        features = black.get_features_used(root)
+        self.assertIn(black.Feature.ASSIGNMENT_EXPRESSIONS, features)
+        versions = black.detect_target_versions(root)
+        self.assertIn(black.TargetVersion.PY38, versions)
 
     def test_expression_ff(self) -> None:
         source, expected = read_data("expression")
@@ -187,29 +309,30 @@ class BlackTestCase(unittest.TestCase):
         self.assertFormatEqual(expected, actual)
         with patch("black.dump_to_file", dump_to_stderr):
             black.assert_equivalent(source, actual)
-            black.assert_stable(source, actual, line_length=ll)
+            black.assert_stable(source, actual, black.FileMode())
 
     def test_expression_diff(self) -> None:
         source, _ = read_data("expression.py")
         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
-        hold_stdout = sys.stdout
+        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"
+        )
         try:
-            sys.stdout = StringIO()
-            self.assertTrue(ff(tmp_file, write_back=black.WriteBack.DIFF))
-            sys.stdout.seek(0)
-            actual = sys.stdout.read()
-            actual = actual.replace(tmp_file.name, "<stdin>")
+            result = BlackRunner().invoke(black.main, ["--diff", str(tmp_file)])
+            self.assertEqual(result.exit_code, 0)
         finally:
-            sys.stdout = hold_stdout
             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 = (
                 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/expression.diff with {dump}"
+                f"overwrite tests/data/expression.diff with {dump}"
             )
             self.assertEqual(expected, actual, msg)
 
@@ -219,7 +342,24 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
+
+    @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())
+        if sys.version_info >= (3, 8):
+            black.assert_equivalent(source, actual)
+
+    def test_detect_pos_only_arguments(self) -> None:
+        source, _ = read_data("pep_570")
+        root = black.lib2to3_parse(source)
+        features = black.get_features_used(root)
+        self.assertIn(black.Feature.POS_ONLY_ARGUMENTS, features)
+        versions = black.detect_target_versions(root)
+        self.assertIn(black.TargetVersion.PY38, versions)
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_string_quotes(self) -> None:
@@ -227,7 +367,20 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
+        mode = black.FileMode(string_normalization=False)
+        not_normalized = fs(source, mode=mode)
+        self.assertFormatEqual(source, 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_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())
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments(self) -> None:
@@ -235,7 +388,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments2(self) -> None:
@@ -243,7 +396,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments3(self) -> None:
@@ -251,7 +404,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments4(self) -> None:
@@ -259,7 +412,39 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
+
+    @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, black.FileMode())
+
+    @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, black.FileMode())
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_comments7(self) -> None:
+        source, expected = read_data("comments7")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, black.FileMode())
+
+    @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, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_cantfit(self) -> None:
@@ -267,7 +452,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_import_spacing(self) -> None:
@@ -275,7 +460,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_composition(self) -> None:
@@ -283,7 +468,7 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_empty_lines(self) -> None:
@@ -291,15 +476,111 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
+
+    @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, black.FileMode())
+
+    @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, black.FileMode())
+
+    @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)
+        actual = fs(source, mode=mode)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, mode)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_numeric_literals_ignoring_underscores(self) -> None:
+        source, expected = read_data("numeric_literals_skip_underscores")
+        mode = black.FileMode(target_versions=black.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, black.FileMode())
 
     @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, line_length=ll)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, black.FileMode())
+
+    @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})
+        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_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, black.FileMode())
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_stub(self) -> None:
+        mode = black.FileMode(is_pyi=True)
+        source, expected = read_data("stub.pyi")
+        actual = fs(source, mode=mode)
+        self.assertFormatEqual(expected, actual)
+        black.assert_stable(source, actual, mode)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_async_as_identifier(self) -> None:
+        source_path = (THIS_DIR / "data" / "async_as_identifier.py").resolve()
+        source, expected = read_data("async_as_identifier")
+        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, black.FileMode())
+        # 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, black.FileMode())
+        # 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_fmtonoff(self) -> None:
@@ -307,10 +588,72 @@ class BlackTestCase(unittest.TestCase):
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
-        black.assert_stable(source, actual, line_length=ll)
+        black.assert_stable(source, actual, black.FileMode())
 
-    def test_report(self) -> None:
-        report = black.Report()
+    @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, black.FileMode())
+
+    @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, black.FileMode())
+
+    @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, black.FileMode())
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_bracket_match(self) -> None:
+        source, expected = read_data("bracketmatch")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, black.FileMode())
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_tuple_assign(self) -> None:
+        source, expected = read_data("tupleassign")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, black.FileMode())
+
+    def test_tab_comment_indentation(self) -> None:
+        contents_tab = "if 1:\n\tif 2:\n\t\tpass\n\t# comment\n\tpass\n"
+        contents_spc = "if 1:\n    if 2:\n        pass\n    # comment\n    pass\n"
+        self.assertFormatEqual(contents_spc, fs(contents_spc))
+        self.assertFormatEqual(contents_spc, fs(contents_tab))
+
+        contents_tab = "if 1:\n\tif 2:\n\t\tpass\n\t\t# comment\n\tpass\n"
+        contents_spc = "if 1:\n    if 2:\n        pass\n        # comment\n    pass\n"
+        self.assertFormatEqual(contents_spc, fs(contents_spc))
+        self.assertFormatEqual(contents_spc, fs(contents_tab))
+
+        # mixed tabs and spaces (valid Python 2 code)
+        contents_tab = "if 1:\n        if 2:\n\t\tpass\n\t# comment\n        pass\n"
+        contents_spc = "if 1:\n    if 2:\n        pass\n    # comment\n    pass\n"
+        self.assertFormatEqual(contents_spc, fs(contents_spc))
+        self.assertFormatEqual(contents_spc, fs(contents_tab))
+
+        contents_tab = "if 1:\n        if 2:\n\t\tpass\n\t\t# comment\n        pass\n"
+        contents_spc = "if 1:\n    if 2:\n        pass\n        # comment\n    pass\n"
+        self.assertFormatEqual(contents_spc, fs(contents_spc))
+        self.assertFormatEqual(contents_spc, fs(contents_tab))
+
+    def test_report_verbose(self) -> None:
+        report = black.Report(verbose=True)
         out_lines = []
         err_lines = []
 
@@ -377,9 +720,19 @@ class BlackTestCase(unittest.TestCase):
                 "2 files failed to reformat.",
             )
             self.assertEqual(report.return_code, 123)
-            report.done(Path("f4"), black.Changed.NO)
+            report.path_ignored(Path("wat"), "no match")
             self.assertEqual(len(out_lines), 5)
             self.assertEqual(len(err_lines), 2)
+            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.",
+            )
+            self.assertEqual(report.return_code, 123)
+            report.done(Path("f4"), black.Changed.NO)
+            self.assertEqual(len(out_lines), 6)
+            self.assertEqual(len(err_lines), 2)
             self.assertEqual(out_lines[-1], "f4 already well formatted, good job.")
             self.assertEqual(
                 unstyle(str(report)),
@@ -394,23 +747,268 @@ class BlackTestCase(unittest.TestCase):
                 "2 files would fail to reformat.",
             )
 
-    def test_is_python36(self) -> None:
+    def test_report_quiet(self) -> None:
+        report = black.Report(quiet=True)
+        out_lines = []
+        err_lines = []
+
+        def out(msg: str, **kwargs: Any) -> None:
+            out_lines.append(msg)
+
+        def err(msg: str, **kwargs: Any) -> None:
+            err_lines.append(msg)
+
+        with patch("black.out", out), patch("black.err", err):
+            report.done(Path("f1"), black.Changed.NO)
+            self.assertEqual(len(out_lines), 0)
+            self.assertEqual(len(err_lines), 0)
+            self.assertEqual(unstyle(str(report)), "1 file left unchanged.")
+            self.assertEqual(report.return_code, 0)
+            report.done(Path("f2"), black.Changed.YES)
+            self.assertEqual(len(out_lines), 0)
+            self.assertEqual(len(err_lines), 0)
+            self.assertEqual(
+                unstyle(str(report)), "1 file reformatted, 1 file left unchanged."
+            )
+            report.done(Path("f3"), black.Changed.CACHED)
+            self.assertEqual(len(out_lines), 0)
+            self.assertEqual(len(err_lines), 0)
+            self.assertEqual(
+                unstyle(str(report)), "1 file reformatted, 2 files left unchanged."
+            )
+            self.assertEqual(report.return_code, 0)
+            report.check = True
+            self.assertEqual(report.return_code, 1)
+            report.check = False
+            report.failed(Path("e1"), "boom")
+            self.assertEqual(len(out_lines), 0)
+            self.assertEqual(len(err_lines), 1)
+            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.",
+            )
+            self.assertEqual(report.return_code, 123)
+            report.done(Path("f3"), black.Changed.YES)
+            self.assertEqual(len(out_lines), 0)
+            self.assertEqual(len(err_lines), 1)
+            self.assertEqual(
+                unstyle(str(report)),
+                "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(len(out_lines), 0)
+            self.assertEqual(len(err_lines), 2)
+            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.",
+            )
+            self.assertEqual(report.return_code, 123)
+            report.path_ignored(Path("wat"), "no match")
+            self.assertEqual(len(out_lines), 0)
+            self.assertEqual(len(err_lines), 2)
+            self.assertEqual(
+                unstyle(str(report)),
+                "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(len(out_lines), 0)
+            self.assertEqual(len(err_lines), 2)
+            self.assertEqual(
+                unstyle(str(report)),
+                "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)),
+                "2 files would be reformatted, 3 files would be left unchanged, "
+                "2 files would fail to reformat.",
+            )
+
+    def test_report_normal(self) -> None:
+        report = black.Report()
+        out_lines = []
+        err_lines = []
+
+        def out(msg: str, **kwargs: Any) -> None:
+            out_lines.append(msg)
+
+        def err(msg: str, **kwargs: Any) -> None:
+            err_lines.append(msg)
+
+        with patch("black.out", out), patch("black.err", err):
+            report.done(Path("f1"), black.Changed.NO)
+            self.assertEqual(len(out_lines), 0)
+            self.assertEqual(len(err_lines), 0)
+            self.assertEqual(unstyle(str(report)), "1 file left unchanged.")
+            self.assertEqual(report.return_code, 0)
+            report.done(Path("f2"), black.Changed.YES)
+            self.assertEqual(len(out_lines), 1)
+            self.assertEqual(len(err_lines), 0)
+            self.assertEqual(out_lines[-1], "reformatted f2")
+            self.assertEqual(
+                unstyle(str(report)), "1 file reformatted, 1 file left unchanged."
+            )
+            report.done(Path("f3"), black.Changed.CACHED)
+            self.assertEqual(len(out_lines), 1)
+            self.assertEqual(len(err_lines), 0)
+            self.assertEqual(out_lines[-1], "reformatted f2")
+            self.assertEqual(
+                unstyle(str(report)), "1 file reformatted, 2 files left unchanged."
+            )
+            self.assertEqual(report.return_code, 0)
+            report.check = True
+            self.assertEqual(report.return_code, 1)
+            report.check = False
+            report.failed(Path("e1"), "boom")
+            self.assertEqual(len(out_lines), 1)
+            self.assertEqual(len(err_lines), 1)
+            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.",
+            )
+            self.assertEqual(report.return_code, 123)
+            report.done(Path("f3"), black.Changed.YES)
+            self.assertEqual(len(out_lines), 2)
+            self.assertEqual(len(err_lines), 1)
+            self.assertEqual(out_lines[-1], "reformatted f3")
+            self.assertEqual(
+                unstyle(str(report)),
+                "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(len(out_lines), 2)
+            self.assertEqual(len(err_lines), 2)
+            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.",
+            )
+            self.assertEqual(report.return_code, 123)
+            report.path_ignored(Path("wat"), "no match")
+            self.assertEqual(len(out_lines), 2)
+            self.assertEqual(len(err_lines), 2)
+            self.assertEqual(
+                unstyle(str(report)),
+                "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(len(out_lines), 2)
+            self.assertEqual(len(err_lines), 2)
+            self.assertEqual(
+                unstyle(str(report)),
+                "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)),
+                "2 files would be reformatted, 3 files would be left unchanged, "
+                "2 files would fail to reformat.",
+            )
+
+    def test_lib2to3_parse(self) -> None:
+        with self.assertRaises(black.InvalidInput):
+            black.lib2to3_parse("invalid syntax")
+
+        straddling = "x + y"
+        black.lib2to3_parse(straddling)
+        black.lib2to3_parse(straddling, {TargetVersion.PY27})
+        black.lib2to3_parse(straddling, {TargetVersion.PY36})
+        black.lib2to3_parse(straddling, {TargetVersion.PY27, TargetVersion.PY36})
+
+        py2_only = "print x"
+        black.lib2to3_parse(py2_only)
+        black.lib2to3_parse(py2_only, {TargetVersion.PY27})
+        with self.assertRaises(black.InvalidInput):
+            black.lib2to3_parse(py2_only, {TargetVersion.PY36})
+        with self.assertRaises(black.InvalidInput):
+            black.lib2to3_parse(py2_only, {TargetVersion.PY27, TargetVersion.PY36})
+
+        py3_only = "exec(x, end=y)"
+        black.lib2to3_parse(py3_only)
+        with self.assertRaises(black.InvalidInput):
+            black.lib2to3_parse(py3_only, {TargetVersion.PY27})
+        black.lib2to3_parse(py3_only, {TargetVersion.PY36})
+        black.lib2to3_parse(py3_only, {TargetVersion.PY27, TargetVersion.PY36})
+
+    def test_get_features_used(self) -> None:
         node = black.lib2to3_parse("def f(*, arg): ...\n")
-        self.assertFalse(black.is_python36(node))
+        self.assertEqual(black.get_features_used(node), set())
         node = black.lib2to3_parse("def f(*, arg,): ...\n")
-        self.assertTrue(black.is_python36(node))
+        self.assertEqual(black.get_features_used(node), {Feature.TRAILING_COMMA_IN_DEF})
+        node = black.lib2to3_parse("f(*arg,)\n")
+        self.assertEqual(
+            black.get_features_used(node), {Feature.TRAILING_COMMA_IN_CALL}
+        )
         node = black.lib2to3_parse("def f(*, arg): f'string'\n")
-        self.assertTrue(black.is_python36(node))
+        self.assertEqual(black.get_features_used(node), {Feature.F_STRINGS})
+        node = black.lib2to3_parse("123_456\n")
+        self.assertEqual(black.get_features_used(node), {Feature.NUMERIC_UNDERSCORES})
+        node = black.lib2to3_parse("123456\n")
+        self.assertEqual(black.get_features_used(node), set())
         source, expected = read_data("function")
         node = black.lib2to3_parse(source)
-        self.assertTrue(black.is_python36(node))
+        expected_features = {
+            Feature.TRAILING_COMMA_IN_CALL,
+            Feature.TRAILING_COMMA_IN_DEF,
+            Feature.F_STRINGS,
+        }
+        self.assertEqual(black.get_features_used(node), expected_features)
         node = black.lib2to3_parse(expected)
-        self.assertTrue(black.is_python36(node))
+        self.assertEqual(black.get_features_used(node), expected_features)
         source, expected = read_data("expression")
         node = black.lib2to3_parse(source)
-        self.assertFalse(black.is_python36(node))
+        self.assertEqual(black.get_features_used(node), set())
         node = black.lib2to3_parse(expected)
-        self.assertFalse(black.is_python36(node))
+        self.assertEqual(black.get_features_used(node), set())
+
+    def test_get_future_imports(self) -> None:
+        node = black.lib2to3_parse("\n")
+        self.assertEqual(set(), black.get_future_imports(node))
+        node = black.lib2to3_parse("from __future__ import black\n")
+        self.assertEqual({"black"}, black.get_future_imports(node))
+        node = black.lib2to3_parse("from __future__ import multiple, imports\n")
+        self.assertEqual({"multiple", "imports"}, black.get_future_imports(node))
+        node = black.lib2to3_parse("from __future__ import (parenthesized, imports)\n")
+        self.assertEqual({"parenthesized", "imports"}, black.get_future_imports(node))
+        node = black.lib2to3_parse(
+            "from __future__ import multiple\nfrom __future__ import imports\n"
+        )
+        self.assertEqual({"multiple", "imports"}, black.get_future_imports(node))
+        node = black.lib2to3_parse("# comment\nfrom __future__ import black\n")
+        self.assertEqual({"black"}, black.get_future_imports(node))
+        node = black.lib2to3_parse('"""docstring"""\nfrom __future__ import black\n')
+        self.assertEqual({"black"}, black.get_future_imports(node))
+        node = black.lib2to3_parse("some(other, code)\nfrom __future__ import black\n")
+        self.assertEqual(set(), black.get_future_imports(node))
+        node = black.lib2to3_parse("from some.module import black\n")
+        self.assertEqual(set(), black.get_future_imports(node))
+        node = black.lib2to3_parse(
+            "from __future__ import unicode_literals as _unicode_literals"
+        )
+        self.assertEqual({"unicode_literals"}, black.get_future_imports(node))
+        node = black.lib2to3_parse(
+            "from __future__ import unicode_literals as _lol, print"
+        )
+        self.assertEqual({"unicode_literals", "print"}, black.get_future_imports(node))
 
     def test_debug_visitor(self) -> None:
         source, _ = read_data("debug_visitor.py")
@@ -438,21 +1036,22 @@ class BlackTestCase(unittest.TestCase):
 
     def test_format_file_contents(self) -> None:
         empty = ""
+        mode = black.FileMode()
         with self.assertRaises(black.NothingChanged):
-            black.format_file_contents(empty, line_length=ll, fast=False)
+            black.format_file_contents(empty, mode=mode, fast=False)
         just_nl = "\n"
         with self.assertRaises(black.NothingChanged):
-            black.format_file_contents(just_nl, line_length=ll, fast=False)
+            black.format_file_contents(just_nl, mode=mode, fast=False)
         same = "l = [1, 2, 3]\n"
         with self.assertRaises(black.NothingChanged):
-            black.format_file_contents(same, line_length=ll, fast=False)
+            black.format_file_contents(same, mode=mode, fast=False)
         different = "l = [1,2,3]"
         expected = same
-        actual = black.format_file_contents(different, line_length=ll, fast=False)
+        actual = black.format_file_contents(different, mode=mode, fast=False)
         self.assertEqual(expected, actual)
         invalid = "return if you can"
-        with self.assertRaises(ValueError) as e:
-            black.format_file_contents(invalid, line_length=ll, fast=False)
+        with self.assertRaises(black.InvalidInput) as e:
+            black.format_file_contents(invalid, mode=mode, fast=False)
         self.assertEqual(str(e.exception), "Cannot parse: 1:7: return if you can")
 
     def test_endmarker(self) -> None:
@@ -482,74 +1081,84 @@ class BlackTestCase(unittest.TestCase):
         self.assertEqual("".join(err_lines), "")
 
     def test_cache_broken_file(self) -> None:
+        mode = black.FileMode()
         with cache_dir() as workspace:
-            with black.CACHE_FILE.open("w") as fobj:
+            cache_file = black.get_cache_file(mode)
+            with cache_file.open("w") as fobj:
                 fobj.write("this is not a pickle")
-            self.assertEqual(black.read_cache(), {})
+            self.assertEqual(black.read_cache(mode), {})
             src = (workspace / "test.py").resolve()
             with src.open("w") as fobj:
                 fobj.write("print('hello')")
-            result = CliRunner().invoke(black.main, [str(src)])
-            self.assertEqual(result.exit_code, 0)
-            cache = black.read_cache()
+            self.invokeBlack([str(src)])
+            cache = black.read_cache(mode)
             self.assertIn(src, cache)
 
     def test_cache_single_file_already_cached(self) -> None:
+        mode = black.FileMode()
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             with src.open("w") as fobj:
                 fobj.write("print('hello')")
-            black.write_cache({}, [src])
-            result = CliRunner().invoke(black.main, [str(src)])
-            self.assertEqual(result.exit_code, 0)
+            black.write_cache({}, [src], mode)
+            self.invokeBlack([str(src)])
             with src.open("r") as fobj:
                 self.assertEqual(fobj.read(), "print('hello')")
 
     @event_loop(close=False)
     def test_cache_multiple_files(self) -> None:
-        with cache_dir() as workspace:
+        mode = black.FileMode()
+        with cache_dir() as workspace, patch(
+            "black.ProcessPoolExecutor", new=ThreadPoolExecutor
+        ):
             one = (workspace / "one.py").resolve()
             with one.open("w") as fobj:
                 fobj.write("print('hello')")
             two = (workspace / "two.py").resolve()
             with two.open("w") as fobj:
                 fobj.write("print('hello')")
-            black.write_cache({}, [one])
-            result = CliRunner().invoke(black.main, [str(workspace)])
-            self.assertEqual(result.exit_code, 0)
+            black.write_cache({}, [one], mode)
+            self.invokeBlack([str(workspace)])
             with one.open("r") as fobj:
                 self.assertEqual(fobj.read(), "print('hello')")
             with two.open("r") as fobj:
                 self.assertEqual(fobj.read(), 'print("hello")\n')
-            cache = black.read_cache()
+            cache = black.read_cache(mode)
             self.assertIn(one, cache)
             self.assertIn(two, cache)
 
     def test_no_cache_when_writeback_diff(self) -> None:
+        mode = black.FileMode()
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             with src.open("w") as fobj:
                 fobj.write("print('hello')")
-            result = CliRunner().invoke(black.main, [str(src), "--diff"])
-            self.assertEqual(result.exit_code, 0)
-            self.assertFalse(black.CACHE_FILE.exists())
+            self.invokeBlack([str(src), "--diff"])
+            cache_file = black.get_cache_file(mode)
+            self.assertFalse(cache_file.exists())
 
     def test_no_cache_when_stdin(self) -> None:
+        mode = black.FileMode()
         with cache_dir():
-            result = CliRunner().invoke(black.main, ["-"], input="print('hello')")
+            result = CliRunner().invoke(
+                black.main, ["-"], input=BytesIO(b"print('hello')")
+            )
             self.assertEqual(result.exit_code, 0)
-            self.assertFalse(black.CACHE_FILE.exists())
+            cache_file = black.get_cache_file(mode)
+            self.assertFalse(cache_file.exists())
 
     def test_read_cache_no_cachefile(self) -> None:
+        mode = black.FileMode()
         with cache_dir():
-            self.assertEqual(black.read_cache(), {})
+            self.assertEqual(black.read_cache(mode), {})
 
     def test_write_cache_read_cache(self) -> None:
+        mode = black.FileMode()
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.touch()
-            black.write_cache({}, [src])
-            cache = black.read_cache()
+            black.write_cache({}, [src], mode)
+            cache = black.read_cache(mode)
             self.assertIn(src, cache)
             self.assertEqual(cache[src], black.get_cache_info(src))
 
@@ -564,37 +1173,497 @@ class BlackTestCase(unittest.TestCase):
             cached_but_changed.touch()
             cache = {cached: black.get_cache_info(cached), cached_but_changed: (0.0, 0)}
             todo, done = black.filter_cached(
-                cache, [uncached, cached, cached_but_changed]
+                cache, {uncached, cached, cached_but_changed}
             )
-            self.assertEqual(todo, [uncached, cached_but_changed])
-            self.assertEqual(done, [cached])
+            self.assertEqual(todo, {uncached, cached_but_changed})
+            self.assertEqual(done, {cached})
 
     def test_write_cache_creates_directory_if_needed(self) -> None:
+        mode = black.FileMode()
         with cache_dir(exists=False) as workspace:
             self.assertFalse(workspace.exists())
-            black.write_cache({}, [])
+            black.write_cache({}, [], mode)
             self.assertTrue(workspace.exists())
 
     @event_loop(close=False)
     def test_failed_formatting_does_not_get_cached(self) -> None:
-        with cache_dir() as workspace:
+        mode = black.FileMode()
+        with cache_dir() as workspace, patch(
+            "black.ProcessPoolExecutor", new=ThreadPoolExecutor
+        ):
             failing = (workspace / "failing.py").resolve()
             with failing.open("w") as fobj:
                 fobj.write("not actually python")
             clean = (workspace / "clean.py").resolve()
             with clean.open("w") as fobj:
                 fobj.write('print("hello")\n')
-            result = CliRunner().invoke(black.main, [str(workspace)])
-            self.assertEqual(result.exit_code, 123)
-            cache = black.read_cache()
+            self.invokeBlack([str(workspace)], exit_code=123)
+            cache = black.read_cache(mode)
             self.assertNotIn(failing, cache)
             self.assertIn(clean, cache)
 
     def test_write_cache_write_fail(self) -> None:
+        mode = black.FileMode()
         with cache_dir(), patch.object(Path, "open") as mock:
             mock.side_effect = OSError
-            black.write_cache({}, [])
+            black.write_cache({}, [], mode)
+
+    @event_loop(close=False)
+    def test_check_diff_use_together(self) -> None:
+        with cache_dir():
+            # Files which will be reformatted.
+            src1 = (THIS_DIR / "data" / "string_quotes.py").resolve()
+            self.invokeBlack([str(src1), "--diff", "--check"], exit_code=1)
+            # Files which will not be reformatted.
+            src2 = (THIS_DIR / "data" / "composition.py").resolve()
+            self.invokeBlack([str(src2), "--diff", "--check"])
+            # Multi file command.
+            self.invokeBlack([str(src1), str(src2), "--diff", "--check"], exit_code=1)
+
+    def test_no_files(self) -> None:
+        with cache_dir():
+            # Without an argument, black exits with error code 0.
+            self.invokeBlack([])
+
+    def test_broken_symlink(self) -> None:
+        with cache_dir() as workspace:
+            symlink = workspace / "broken_link.py"
+            try:
+                symlink.symlink_to("nonexistent.py")
+            except OSError as e:
+                self.skipTest(f"Can't create symlinks: {e}")
+            self.invokeBlack([str(workspace.resolve())])
+
+    def test_read_cache_line_lengths(self) -> None:
+        mode = black.FileMode()
+        short_mode = black.FileMode(line_length=1)
+        with cache_dir() as workspace:
+            path = (workspace / "file.py").resolve()
+            path.touch()
+            black.write_cache({}, [path], mode)
+            one = black.read_cache(mode)
+            self.assertIn(path, one)
+            two = black.read_cache(short_mode)
+            self.assertNotIn(path, two)
+
+    def test_single_file_force_pyi(self) -> None:
+        reg_mode = black.FileMode()
+        pyi_mode = black.FileMode(is_pyi=True)
+        contents, expected = read_data("force_pyi")
+        with cache_dir() as workspace:
+            path = (workspace / "file.py").resolve()
+            with open(path, "w") as fh:
+                fh.write(contents)
+            self.invokeBlack([str(path), "--pyi"])
+            with open(path, "r") as fh:
+                actual = fh.read()
+            # verify cache with --pyi is separate
+            pyi_cache = black.read_cache(pyi_mode)
+            self.assertIn(path, pyi_cache)
+            normal_cache = black.read_cache(reg_mode)
+            self.assertNotIn(path, normal_cache)
+        self.assertEqual(actual, expected)
+
+    @event_loop(close=False)
+    def test_multi_file_force_pyi(self) -> None:
+        reg_mode = black.FileMode()
+        pyi_mode = black.FileMode(is_pyi=True)
+        contents, expected = read_data("force_pyi")
+        with cache_dir() as workspace:
+            paths = [
+                (workspace / "file1.py").resolve(),
+                (workspace / "file2.py").resolve(),
+            ]
+            for path in paths:
+                with open(path, "w") as fh:
+                    fh.write(contents)
+            self.invokeBlack([str(p) for p in paths] + ["--pyi"])
+            for path in paths:
+                with open(path, "r") as fh:
+                    actual = fh.read()
+                self.assertEqual(actual, expected)
+            # verify cache with --pyi is separate
+            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)
+
+    def test_pipe_force_pyi(self) -> None:
+        source, expected = read_data("force_pyi")
+        result = CliRunner().invoke(
+            black.main, ["-", "-q", "--pyi"], input=BytesIO(source.encode("utf8"))
+        )
+        self.assertEqual(result.exit_code, 0)
+        actual = result.output
+        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)
+        source, expected = read_data("force_py36")
+        with cache_dir() as workspace:
+            path = (workspace / "file.py").resolve()
+            with open(path, "w") as fh:
+                fh.write(source)
+            self.invokeBlack([str(path), *PY36_ARGS])
+            with open(path, "r") as fh:
+                actual = fh.read()
+            # verify cache with --target-version is separate
+            py36_cache = black.read_cache(py36_mode)
+            self.assertIn(path, py36_cache)
+            normal_cache = black.read_cache(reg_mode)
+            self.assertNotIn(path, normal_cache)
+        self.assertEqual(actual, expected)
+
+    @event_loop(close=False)
+    def test_multi_file_force_py36(self) -> None:
+        reg_mode = black.FileMode()
+        py36_mode = black.FileMode(target_versions=black.PY36_VERSIONS)
+        source, expected = read_data("force_py36")
+        with cache_dir() as workspace:
+            paths = [
+                (workspace / "file1.py").resolve(),
+                (workspace / "file2.py").resolve(),
+            ]
+            for path in paths:
+                with open(path, "w") as fh:
+                    fh.write(source)
+            self.invokeBlack([str(p) for p in paths] + PY36_ARGS)
+            for path in paths:
+                with open(path, "r") as fh:
+                    actual = fh.read()
+                self.assertEqual(actual, expected)
+            # verify cache with --target-version is separate
+            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_pipe_force_py36(self) -> None:
+        source, expected = read_data("force_py36")
+        result = CliRunner().invoke(
+            black.main,
+            ["-", "-q", "--target-version=py36"],
+            input=BytesIO(source.encode("utf8")),
+        )
+        self.assertEqual(result.exit_code, 0)
+        actual = result.output
+        self.assertFormatEqual(actual, expected)
+
+    def test_include_exclude(self) -> None:
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        include = re.compile(r"\.pyi?$")
+        exclude = re.compile(r"/exclude/|/\.definitely_exclude/")
+        report = black.Report()
+        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_in_dir(path, this_abs, include, exclude, report)
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    def test_empty_include(self) -> None:
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        report = black.Report()
+        empty = re.compile(r"")
+        sources: List[Path] = []
+        expected = [
+            Path(path / "b/exclude/a.pie"),
+            Path(path / "b/exclude/a.py"),
+            Path(path / "b/exclude/a.pyi"),
+            Path(path / "b/dont_exclude/a.pie"),
+            Path(path / "b/dont_exclude/a.py"),
+            Path(path / "b/dont_exclude/a.pyi"),
+            Path(path / "b/.definitely_exclude/a.pie"),
+            Path(path / "b/.definitely_exclude/a.py"),
+            Path(path / "b/.definitely_exclude/a.pyi"),
+        ]
+        this_abs = THIS_DIR.resolve()
+        sources.extend(
+            black.gen_python_files_in_dir(
+                path, this_abs, empty, re.compile(black.DEFAULT_EXCLUDES), report
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    def test_empty_exclude(self) -> None:
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        report = black.Report()
+        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"),
+        ]
+        this_abs = THIS_DIR.resolve()
+        sources.extend(
+            black.gen_python_files_in_dir(
+                path, this_abs, re.compile(black.DEFAULT_INCLUDES), empty, report
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    def test_invalid_include_exclude(self) -> None:
+        for option in ["--include", "--exclude"]:
+            self.invokeBlack(["-", option, "**()(!!*)"], exit_code=2)
+
+    def test_preserves_line_endings(self) -> None:
+        with TemporaryDirectory() as workspace:
+            test_file = Path(workspace) / "test.py"
+            for nl in ["\n", "\r\n"]:
+                contents = nl.join(["def f(  ):", "    pass"])
+                test_file.write_bytes(contents.encode())
+                ff(test_file, write_back=black.WriteBack.YES)
+                updated_contents: bytes = test_file.read_bytes()
+                self.assertIn(nl.encode(), updated_contents)
+                if nl == "\n":
+                    self.assertNotIn(b"\r\n", updated_contents)
+
+    def test_preserves_line_endings_via_stdin(self) -> None:
+        for nl in ["\n", "\r\n"]:
+            contents = nl.join(["def f(  ):", "    pass"])
+            runner = BlackRunner()
+            result = runner.invoke(
+                black.main, ["-", "--fast"], input=BytesIO(contents.encode("utf8"))
+            )
+            self.assertEqual(result.exit_code, 0)
+            output = runner.stdout_bytes
+            self.assertIn(nl.encode("utf8"), output)
+            if nl == "\n":
+                self.assertNotIn(b"\r\n", output)
+
+    def test_assert_equivalent_different_asts(self) -> None:
+        with self.assertRaises(AssertionError):
+            black.assert_equivalent("{}", "None")
+
+    def test_symlink_out_of_root_directory(self) -> None:
+        path = MagicMock()
+        root = THIS_DIR
+        child = MagicMock()
+        include = re.compile(black.DEFAULT_INCLUDES)
+        exclude = re.compile(black.DEFAULT_EXCLUDES)
+        report = black.Report()
+        # `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.is_symlink.return_value = True
+        try:
+            list(black.gen_python_files_in_dir(path, root, include, exclude, report))
+        except ValueError as ve:
+            self.fail(f"`get_python_files_in_dir()` failed: {ve}")
+        path.iterdir.assert_called_once()
+        child.resolve.assert_called_once()
+        child.is_symlink.assert_called_once()
+        # `child` should behave like a strange file which resolved path is clearly
+        # outside of the `root` directory.
+        child.is_symlink.return_value = False
+        with self.assertRaises(ValueError):
+            list(black.gen_python_files_in_dir(path, root, include, exclude, report))
+        path.iterdir.assert_called()
+        self.assertEqual(path.iterdir.call_count, 2)
+        child.resolve.assert_called()
+        self.assertEqual(child.resolve.call_count, 2)
+        child.is_symlink.assert_called()
+        self.assertEqual(child.is_symlink.call_count, 2)
+
+    def test_shhh_click(self) -> None:
+        try:
+            from click import _unicodefun  # type: ignore
+        except ModuleNotFoundError:
+            self.skipTest("Incompatible Click version")
+        if not hasattr(_unicodefun, "_verify_python3_env"):
+            self.skipTest("Incompatible Click version")
+        # First, let's see if Click is crashing with a preferred ASCII charset.
+        with patch("locale.getpreferredencoding") as gpe:
+            gpe.return_value = "ASCII"
+            with self.assertRaises(RuntimeError):
+                _unicodefun._verify_python3_env()
+        # Now, let's silence Click...
+        black.patch_click()
+        # ...and confirm it's silent.
+        with patch("locale.getpreferredencoding") as gpe:
+            gpe.return_value = "ASCII"
+            try:
+                _unicodefun._verify_python3_env()
+            except RuntimeError as re:
+                self.fail(f"`patch_click()` failed, exception still raised: {re}")
+
+    def test_root_logger_not_used_directly(self) -> None:
+        def fail(*args: Any, **kwargs: Any) -> None:
+            self.fail("Record created with root logger")
+
+        with patch.multiple(
+            logging.root,
+            debug=fail,
+            info=fail,
+            warning=fail,
+            error=fail,
+            critical=fail,
+            log=fail,
+        ):
+            ff(THIS_FILE)
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_request_needs_formatting(self) -> None:
+        app = blackd.make_app()
+        async with TestClient(TestServer(app)) as client:
+            response = await 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')
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_request_no_change(self) -> None:
+        app = blackd.make_app()
+        async with TestClient(TestServer(app)) as client:
+            response = await client.post("/", data=b'print("hello world")\n')
+            self.assertEqual(response.status, 204)
+            self.assertEqual(await response.read(), b"")
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_request_syntax_error(self) -> None:
+        app = blackd.make_app()
+        async with TestClient(TestServer(app)) as client:
+            response = await 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)}",
+            )
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_unsupported_version(self) -> None:
+        app = blackd.make_app()
+        async with TestClient(TestServer(app)) as client:
+            response = await client.post(
+                "/", data=b"what", headers={blackd.VERSION_HEADER: "2"}
+            )
+            self.assertEqual(response.status, 501)
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_supported_version(self) -> None:
+        app = blackd.make_app()
+        async with TestClient(TestServer(app)) as client:
+            response = await client.post(
+                "/", data=b"what", headers={blackd.VERSION_HEADER: "1"}
+            )
+            self.assertEqual(response.status, 200)
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_invalid_python_variant(self) -> None:
+        app = blackd.make_app()
+        async with TestClient(TestServer(app)) as client:
+
+            async def check(header_value: str, expected_status: int = 400) -> None:
+                response = await 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")
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_pyi(self) -> None:
+        app = blackd.make_app()
+        async with TestClient(TestServer(app)) as client:
+            source, expected = read_data("stub.pyi")
+            response = await client.post(
+                "/", data=source, headers={blackd.PYTHON_VARIANT_HEADER: "pyi"}
+            )
+            self.assertEqual(response.status, 200)
+            self.assertEqual(await response.text(), expected)
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_python_variant(self) -> None:
+        app = blackd.make_app()
+        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"
+        )
+        async with TestClient(TestServer(app)) as client:
+
+            async def check(header_value: str, expected_status: int) -> None:
+                response = await client.post(
+                    "/", data=code, headers={blackd.PYTHON_VARIANT_HEADER: header_value}
+                )
+                self.assertEqual(response.status, expected_status)
+
+            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("2", 204)
+            await check("2.7", 204)
+            await check("py2.7", 204)
+            await check("3.4", 204)
+            await check("py3.4", 204)
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_line_length(self) -> None:
+        app = blackd.make_app()
+        async with TestClient(TestServer(app)) as client:
+            response = await client.post(
+                "/", data=b'print("hello")\n', headers={blackd.LINE_LENGTH_HEADER: "7"}
+            )
+            self.assertEqual(response.status, 200)
+
+    @unittest.skipUnless(has_blackd_deps, "blackd's dependencies are not installed")
+    @async_test
+    async def test_blackd_invalid_line_length(self) -> None:
+        app = blackd.make_app()
+        async with TestClient(TestServer(app)) as client:
+            response = await client.post(
+                "/",
+                data=b'print("hello")\n',
+                headers={blackd.LINE_LENGTH_HEADER: "NaN"},
+            )
+            self.assertEqual(response.status, 400)
+
+    @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)
 
 
 if __name__ == "__main__":
-    unittest.main()
+    unittest.main(module="test_black")