]> 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:

pre-commit: use exclusion instead of ever-growing regex (#382)
[etc/vim.git] / tests / test_black.py
index 1c22e54db7a03f5addb06bf98b13dad527401893..cc53aa61221e346fc144b2106a2a3077aca9f193 100644 (file)
@@ -1,41 +1,49 @@
 #!/usr/bin/env python3
+import asyncio
+from concurrent.futures import ThreadPoolExecutor
+from contextlib import contextmanager
 from functools import partial
-from io import StringIO
+from io import BytesIO, TextIOWrapper
 import os
 from pathlib import Path
+import re
 import sys
-from typing import Any, List, Tuple
+from tempfile import TemporaryDirectory
+from typing import Any, BinaryIO, Generator, List, Tuple, Iterator
 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)
 THIS_FILE = Path(__file__)
 THIS_DIR = THIS_FILE.parent
-EMPTY_LINE = '# EMPTY LINE WITH WHITESPACE' + ' (this comment will be removed)'
+EMPTY_LINE = "# EMPTY LINE WITH WHITESPACE" + " (this comment will be removed)"
 
 
 def dump_to_stderr(*output: str) -> str:
-    return '\n' + '\n'.join(output) + '\n'
+    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')):
-        name += '.py'
+    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:
-        line = line.replace(EMPTY_LINE, '')
-        if line.rstrip() == '# output':
+        line = line.replace(EMPTY_LINE, "")
+        if line.rstrip() == "# output":
             result = _output
             continue
 
@@ -43,23 +51,68 @@ def read_data(name: str) -> Tuple[str, str]:
     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'
+    return "".join(_input).strip() + "\n", "".join(_output).strip() + "\n"
+
+
+@contextmanager
+def cache_dir(exists: bool = True) -> Iterator[Path]:
+    with TemporaryDirectory() as workspace:
+        cache_dir = Path(workspace)
+        if not exists:
+            cache_dir = cache_dir / "new"
+        with patch("black.CACHE_DIR", cache_dir):
+            yield cache_dir
+
+
+@contextmanager
+def event_loop(close: bool) -> Iterator[None]:
+    policy = asyncio.get_event_loop_policy()
+    old_loop = policy.get_event_loop()
+    loop = policy.new_event_loop()
+    asyncio.set_event_loop(loop)
+    try:
+        yield
+
+    finally:
+        policy.set_event_loop(old_loop)
+        if close:
+            loop.close()
+
+
+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, stderrbuf: BinaryIO) -> None:
+        self.stderrbuf = stderrbuf
+        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:
+                sys.stderr = hold_stderr
 
 
 class BlackTestCase(unittest.TestCase):
     maxDiff = None
 
     def assertFormatEqual(self, expected: str, actual: str) -> None:
-        if actual != expected and not os.environ.get('SKIP_AST_PRINT'):
+        if actual != expected and not os.environ.get("SKIP_AST_PRINT"):
             bdv: black.DebugVisitor[Any]
-            black.out('Expected tree:', fg='green')
+            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')
+            black.out("Actual tree:", fg="red")
             try:
                 exp_node = black.lib2to3_parse(actual)
                 bdv = black.DebugVisitor()
@@ -68,9 +121,28 @@ class BlackTestCase(unittest.TestCase):
                 black.err(str(ve))
         self.assertEqual(expected, actual)
 
+    @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, line_length=ll)
+
+    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)
@@ -79,40 +151,60 @@ class BlackTestCase(unittest.TestCase):
 
     @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)
-        self.assertFalse(ff(THIS_DIR / '..' / 'black.py'))
+        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=True)
-            sys.stdout.seek(0)
-            actual = sys.stdout.read()
-        finally:
-            sys.stdin, sys.stdout = hold_stdin, hold_stdout
+        source, expected = read_data("../black", data=False)
+        stderrbuf = BytesIO()
+        result = BlackRunner(stderrbuf).invoke(
+            black.main, ["-", "--fast", f"--line-length={ll}"], input=source
+        )
+        self.assertEqual(result.exit_code, 0)
+        self.assertFormatEqual(expected, result.output)
+        black.assert_equivalent(source, result.output)
+        black.assert_stable(source, result.output, line_length=ll)
+
+    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")
+        config = THIS_DIR / "data" / "empty_pyproject.toml"
+        stderrbuf = BytesIO()
+        args = ["-", "--fast", f"--line-length={ll}", "--diff", f"--config={config}"]
+        result = BlackRunner(stderrbuf).invoke(black.main, args, input=source)
+        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", data=False)
+        actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, line_length=ll)
+        self.assertFalse(ff(THIS_DIR / ".." / "setup.py"))
 
     @patch("black.dump_to_file", dump_to_stderr)
-    def test_setup(self) -> None:
-        source, expected = read_data('../setup')
+    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, line_length=ll)
-        self.assertFalse(ff(THIS_DIR / '..' / 'setup.py'))
 
     @patch("black.dump_to_file", dump_to_stderr)
-    def test_function(self) -> None:
-        source, expected = read_data('function')
+    def test_function2(self) -> None:
+        source, expected = read_data("function2")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
@@ -120,15 +212,78 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_expression(self) -> None:
-        source, expected = read_data('expression')
+        source, expected = read_data("expression")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, line_length=ll)
 
+    def test_expression_ff(self) -> None:
+        source, expected = read_data("expression")
+        tmp_file = Path(black.dump_to_file(source))
+        try:
+            self.assertTrue(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)
+        with patch("black.dump_to_file", dump_to_stderr):
+            black.assert_equivalent(source, actual)
+            black.assert_stable(source, actual, line_length=ll)
+
+    def test_expression_diff(self) -> None:
+        source, _ = read_data("expression.py")
+        expected, _ = read_data("expression.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 "
+            rf"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
+        )
+        stderrbuf = BytesIO()
+        try:
+            result = BlackRunner(stderrbuf).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)
+        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}"
+            )
+            self.assertEqual(expected, actual, msg)
+
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fstring(self) -> None:
-        source, expected = read_data('fstring')
+        source, expected = read_data("fstring")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, line_length=ll)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_string_quotes(self) -> None:
+        source, expected = read_data("string_quotes")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, line_length=ll)
+        mode = black.FileMode.NO_STRING_NORMALIZATION
+        not_normalized = fs(source, mode=mode)
+        self.assertFormatEqual(source, not_normalized)
+        black.assert_equivalent(source, not_normalized)
+        black.assert_stable(source, not_normalized, line_length=ll, 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)
@@ -136,7 +291,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments(self) -> None:
-        source, expected = read_data('comments')
+        source, expected = read_data("comments")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
@@ -144,7 +299,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments2(self) -> None:
-        source, expected = read_data('comments2')
+        source, expected = read_data("comments2")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
@@ -152,7 +307,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments3(self) -> None:
-        source, expected = read_data('comments3')
+        source, expected = read_data("comments3")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
@@ -160,7 +315,15 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments4(self) -> None:
-        source, expected = read_data('comments4')
+        source, expected = read_data("comments4")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, line_length=ll)
+
+    @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)
@@ -168,7 +331,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_cantfit(self) -> None:
-        source, expected = read_data('cantfit')
+        source, expected = read_data("cantfit")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
@@ -176,7 +339,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_import_spacing(self) -> None:
-        source, expected = read_data('import_spacing')
+        source, expected = read_data("import_spacing")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
@@ -184,7 +347,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_composition(self) -> None:
-        source, expected = read_data('composition')
+        source, expected = read_data("composition")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
@@ -192,7 +355,15 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_empty_lines(self) -> None:
-        source, expected = read_data('empty_lines')
+        source, expected = read_data("empty_lines")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_equivalent(source, actual)
+        black.assert_stable(source, actual, line_length=ll)
+
+    @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)
@@ -200,22 +371,61 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2(self) -> None:
-        source, expected = read_data('python2')
+        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)
 
+    @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_stable(source, actual, line_length=ll)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_stub(self) -> None:
+        mode = black.FileMode.PYI
+        source, expected = read_data("stub.pyi")
+        actual = fs(source, mode=mode)
+        self.assertFormatEqual(expected, actual)
+        black.assert_stable(source, actual, line_length=ll, mode=mode)
+
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff(self) -> None:
-        source, expected = read_data('fmtonoff')
+        source, expected = read_data("fmtonoff")
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, line_length=ll)
 
-    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, line_length=ll)
+
+    @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, line_length=ll)
+
+    @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, line_length=ll)
+
+    def test_report_verbose(self) -> None:
+        report = black.Report(verbose=True)
         out_lines = []
         err_lines = []
 
@@ -226,68 +436,264 @@ class BlackTestCase(unittest.TestCase):
             err_lines.append(msg)
 
         with patch("black.out", out), patch("black.err", err):
-            report.done(Path('f1'), changed=False)
+            report.done(Path("f1"), black.Changed.NO)
             self.assertEqual(len(out_lines), 1)
             self.assertEqual(len(err_lines), 0)
-            self.assertEqual(out_lines[-1], 'f1 already well formatted, good job.')
-            self.assertEqual(unstyle(str(report)), '1 file left unchanged.')
+            self.assertEqual(out_lines[-1], "f1 already well formatted, good job.")
+            self.assertEqual(unstyle(str(report)), "1 file left unchanged.")
             self.assertEqual(report.return_code, 0)
-            report.done(Path('f2'), changed=True)
+            report.done(Path("f2"), black.Changed.YES)
             self.assertEqual(len(out_lines), 2)
             self.assertEqual(len(err_lines), 0)
-            self.assertEqual(out_lines[-1], 'reformatted f2')
+            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), 3)
+            self.assertEqual(len(err_lines), 0)
             self.assertEqual(
-                unstyle(str(report)), '1 file reformatted, 1 file left unchanged.'
+                out_lines[-1], "f3 wasn't modified on disk since last run."
+            )
+            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), 2)
+            report.failed(Path("e1"), "boom")
+            self.assertEqual(len(out_lines), 3)
             self.assertEqual(len(err_lines), 1)
-            self.assertEqual(err_lines[-1], 'error: cannot format e1: boom')
+            self.assertEqual(err_lines[-1], "error: cannot format e1: boom")
             self.assertEqual(
                 unstyle(str(report)),
-                '1 file reformatted, 1 file left unchanged, '
-                '1 file failed to reformat.',
+                "1 file reformatted, 2 files left unchanged, "
+                "1 file failed to reformat.",
             )
             self.assertEqual(report.return_code, 123)
-            report.done(Path('f3'), changed=True)
-            self.assertEqual(len(out_lines), 3)
+            report.done(Path("f3"), black.Changed.YES)
+            self.assertEqual(len(out_lines), 4)
             self.assertEqual(len(err_lines), 1)
-            self.assertEqual(out_lines[-1], 'reformatted f3')
+            self.assertEqual(out_lines[-1], "reformatted f3")
             self.assertEqual(
                 unstyle(str(report)),
-                '2 files reformatted, 1 file left unchanged, '
-                '1 file failed to reformat.',
+                "2 files reformatted, 2 files left unchanged, "
+                "1 file failed to reformat.",
             )
             self.assertEqual(report.return_code, 123)
-            report.failed(Path('e2'), 'boom')
-            self.assertEqual(len(out_lines), 3)
+            report.failed(Path("e2"), "boom")
+            self.assertEqual(len(out_lines), 4)
             self.assertEqual(len(err_lines), 2)
-            self.assertEqual(err_lines[-1], 'error: cannot format e2: boom')
+            self.assertEqual(err_lines[-1], "error: cannot format e2: boom")
             self.assertEqual(
                 unstyle(str(report)),
-                '2 files reformatted, 1 file left unchanged, '
-                '2 files failed to reformat.',
+                "2 files reformatted, 2 files left unchanged, "
+                "2 files failed to reformat.",
             )
             self.assertEqual(report.return_code, 123)
-            report.done(Path('f4'), changed=False)
-            self.assertEqual(len(out_lines), 4)
+            report.path_ignored(Path("wat"), "no match")
+            self.assertEqual(len(out_lines), 5)
             self.assertEqual(len(err_lines), 2)
-            self.assertEqual(out_lines[-1], 'f4 already well formatted, good job.')
+            self.assertEqual(out_lines[-1], "wat ignored: no match")
             self.assertEqual(
                 unstyle(str(report)),
-                '2 files reformatted, 2 files left unchanged, '
-                '2 files failed to reformat.',
+                "2 files reformatted, 2 files left unchanged, "
+                "2 files failed to reformat.",
+            )
+            self.assertEqual(report.return_code, 123)
+            report.done(Path("f4"), black.Changed.NO)
+            self.assertEqual(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)),
+                "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, 2 files would be left unchanged, '
-                '2 files would fail to reformat.',
+                "2 files would be reformatted, 3 files would be left unchanged, "
+                "2 files would fail to reformat.",
+            )
+
+    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_is_python36(self) -> None:
@@ -297,20 +703,50 @@ class BlackTestCase(unittest.TestCase):
         self.assertTrue(black.is_python36(node))
         node = black.lib2to3_parse("def f(*, arg): f'string'\n")
         self.assertTrue(black.is_python36(node))
-        source, expected = read_data('function')
+        source, expected = read_data("function")
         node = black.lib2to3_parse(source)
         self.assertTrue(black.is_python36(node))
         node = black.lib2to3_parse(expected)
         self.assertTrue(black.is_python36(node))
-        source, expected = read_data('expression')
+        source, expected = read_data("expression")
         node = black.lib2to3_parse(source)
         self.assertFalse(black.is_python36(node))
         node = black.lib2to3_parse(expected)
         self.assertFalse(black.is_python36(node))
 
+    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')
-        expected, _ = read_data('debug_visitor.out')
+        source, _ = read_data("debug_visitor.py")
+        expected, _ = read_data("debug_visitor.out")
         out_lines = []
         err_lines = []
 
@@ -322,8 +758,8 @@ class BlackTestCase(unittest.TestCase):
 
         with patch("black.out", out), patch("black.err", err):
             black.DebugVisitor.show(source)
-        actual = '\n'.join(out_lines) + '\n'
-        log_name = ''
+        actual = "\n".join(out_lines) + "\n"
+        log_name = ""
         if expected != actual:
             log_name = black.dump_to_file(*out_lines)
         self.assertEqual(
@@ -332,6 +768,467 @@ class BlackTestCase(unittest.TestCase):
             f"AST print out is different. Actual version dumped to {log_name}",
         )
 
+    def test_format_file_contents(self) -> None:
+        empty = ""
+        with self.assertRaises(black.NothingChanged):
+            black.format_file_contents(empty, line_length=ll, fast=False)
+        just_nl = "\n"
+        with self.assertRaises(black.NothingChanged):
+            black.format_file_contents(just_nl, line_length=ll, fast=False)
+        same = "l = [1, 2, 3]\n"
+        with self.assertRaises(black.NothingChanged):
+            black.format_file_contents(same, line_length=ll, fast=False)
+        different = "l = [1,2,3]"
+        expected = same
+        actual = black.format_file_contents(different, line_length=ll, 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)
+        self.assertEqual(str(e.exception), "Cannot parse: 1:7: return if you can")
+
+    def test_endmarker(self) -> None:
+        n = black.lib2to3_parse("\n")
+        self.assertEqual(n.type, black.syms.file_input)
+        self.assertEqual(len(n.children), 1)
+        self.assertEqual(n.children[0].type, black.token.ENDMARKER)
+
+    @unittest.skipIf(os.environ.get("SKIP_AST_PRINT"), "user set SKIP_AST_PRINT")
+    def test_assertFormatEqual(self) -> None:
+        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):
+            with self.assertRaises(AssertionError):
+                self.assertFormatEqual("l = [1, 2, 3]", "l = [1, 2, 3,]")
+
+        out_str = "".join(out_lines)
+        self.assertTrue("Expected tree:" in out_str)
+        self.assertTrue("Actual tree:" in out_str)
+        self.assertEqual("".join(err_lines), "")
+
+    def test_cache_broken_file(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        with cache_dir() as workspace:
+            cache_file = black.get_cache_file(black.DEFAULT_LINE_LENGTH, mode)
+            with cache_file.open("w") as fobj:
+                fobj.write("this is not a pickle")
+            self.assertEqual(black.read_cache(black.DEFAULT_LINE_LENGTH, 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(black.DEFAULT_LINE_LENGTH, mode)
+            self.assertIn(src, cache)
+
+    def test_cache_single_file_already_cached(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        with cache_dir() as workspace:
+            src = (workspace / "test.py").resolve()
+            with src.open("w") as fobj:
+                fobj.write("print('hello')")
+            black.write_cache({}, [src], black.DEFAULT_LINE_LENGTH, mode)
+            result = CliRunner().invoke(black.main, [str(src)])
+            self.assertEqual(result.exit_code, 0)
+            with src.open("r") as fobj:
+                self.assertEqual(fobj.read(), "print('hello')")
+
+    @event_loop(close=False)
+    def test_cache_multiple_files(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        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], black.DEFAULT_LINE_LENGTH, mode)
+            result = CliRunner().invoke(black.main, [str(workspace)])
+            self.assertEqual(result.exit_code, 0)
+            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(black.DEFAULT_LINE_LENGTH, mode)
+            self.assertIn(one, cache)
+            self.assertIn(two, cache)
+
+    def test_no_cache_when_writeback_diff(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        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)
+            cache_file = black.get_cache_file(black.DEFAULT_LINE_LENGTH, mode)
+            self.assertFalse(cache_file.exists())
+
+    def test_no_cache_when_stdin(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        with cache_dir():
+            result = CliRunner().invoke(black.main, ["-"], input="print('hello')")
+            self.assertEqual(result.exit_code, 0)
+            cache_file = black.get_cache_file(black.DEFAULT_LINE_LENGTH, mode)
+            self.assertFalse(cache_file.exists())
+
+    def test_read_cache_no_cachefile(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        with cache_dir():
+            self.assertEqual(black.read_cache(black.DEFAULT_LINE_LENGTH, mode), {})
+
+    def test_write_cache_read_cache(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        with cache_dir() as workspace:
+            src = (workspace / "test.py").resolve()
+            src.touch()
+            black.write_cache({}, [src], black.DEFAULT_LINE_LENGTH, mode)
+            cache = black.read_cache(black.DEFAULT_LINE_LENGTH, mode)
+            self.assertIn(src, cache)
+            self.assertEqual(cache[src], black.get_cache_info(src))
+
+    def test_filter_cached(self) -> None:
+        with TemporaryDirectory() as workspace:
+            path = Path(workspace)
+            uncached = (path / "uncached").resolve()
+            cached = (path / "cached").resolve()
+            cached_but_changed = (path / "changed").resolve()
+            uncached.touch()
+            cached.touch()
+            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}
+            )
+            self.assertEqual(todo, {uncached, cached_but_changed})
+            self.assertEqual(done, {cached})
+
+    def test_write_cache_creates_directory_if_needed(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        with cache_dir(exists=False) as workspace:
+            self.assertFalse(workspace.exists())
+            black.write_cache({}, [], black.DEFAULT_LINE_LENGTH, mode)
+            self.assertTrue(workspace.exists())
+
+    @event_loop(close=False)
+    def test_failed_formatting_does_not_get_cached(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        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(black.DEFAULT_LINE_LENGTH, mode)
+            self.assertNotIn(failing, cache)
+            self.assertIn(clean, cache)
+
+    def test_write_cache_write_fail(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        with cache_dir(), patch.object(Path, "open") as mock:
+            mock.side_effect = OSError
+            black.write_cache({}, [], black.DEFAULT_LINE_LENGTH, 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()
+            result = CliRunner().invoke(black.main, [str(src1), "--diff", "--check"])
+            self.assertEqual(result.exit_code, 1, result.output)
+            # Files which will not be reformatted.
+            src2 = (THIS_DIR / "data" / "composition.py").resolve()
+            result = CliRunner().invoke(black.main, [str(src2), "--diff", "--check"])
+            self.assertEqual(result.exit_code, 0, result.output)
+            # Multi file command.
+            result = CliRunner().invoke(
+                black.main, [str(src1), str(src2), "--diff", "--check"]
+            )
+            self.assertEqual(result.exit_code, 1, result.output)
+
+    def test_no_files(self) -> None:
+        with cache_dir():
+            # Without an argument, black exits with error code 0.
+            result = CliRunner().invoke(black.main, [])
+            self.assertEqual(result.exit_code, 0)
+
+    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}")
+            result = CliRunner().invoke(black.main, [str(workspace.resolve())])
+            self.assertEqual(result.exit_code, 0)
+
+    def test_read_cache_line_lengths(self) -> None:
+        mode = black.FileMode.AUTO_DETECT
+        with cache_dir() as workspace:
+            path = (workspace / "file.py").resolve()
+            path.touch()
+            black.write_cache({}, [path], 1, mode)
+            one = black.read_cache(1, mode)
+            self.assertIn(path, one)
+            two = black.read_cache(2, mode)
+            self.assertNotIn(path, two)
+
+    def test_single_file_force_pyi(self) -> None:
+        reg_mode = black.FileMode.AUTO_DETECT
+        pyi_mode = black.FileMode.PYI
+        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)
+            result = CliRunner().invoke(black.main, [str(path), "--pyi"])
+            self.assertEqual(result.exit_code, 0)
+            with open(path, "r") as fh:
+                actual = fh.read()
+            # verify cache with --pyi is separate
+            pyi_cache = black.read_cache(black.DEFAULT_LINE_LENGTH, pyi_mode)
+            self.assertIn(path, pyi_cache)
+            normal_cache = black.read_cache(black.DEFAULT_LINE_LENGTH, 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.AUTO_DETECT
+        pyi_mode = black.FileMode.PYI
+        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)
+            result = CliRunner().invoke(black.main, [str(p) for p in paths] + ["--pyi"])
+            self.assertEqual(result.exit_code, 0)
+            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(black.DEFAULT_LINE_LENGTH, pyi_mode)
+            normal_cache = black.read_cache(black.DEFAULT_LINE_LENGTH, 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=source)
+        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.AUTO_DETECT
+        py36_mode = black.FileMode.PYTHON36
+        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)
+            result = CliRunner().invoke(black.main, [str(path), "--py36"])
+            self.assertEqual(result.exit_code, 0)
+            with open(path, "r") as fh:
+                actual = fh.read()
+            # verify cache with --py36 is separate
+            py36_cache = black.read_cache(black.DEFAULT_LINE_LENGTH, py36_mode)
+            self.assertIn(path, py36_cache)
+            normal_cache = black.read_cache(black.DEFAULT_LINE_LENGTH, 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.AUTO_DETECT
+        py36_mode = black.FileMode.PYTHON36
+        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)
+            result = CliRunner().invoke(
+                black.main, [str(p) for p in paths] + ["--py36"]
+            )
+            self.assertEqual(result.exit_code, 0)
+            for path in paths:
+                with open(path, "r") as fh:
+                    actual = fh.read()
+                self.assertEqual(actual, expected)
+            # verify cache with --py36 is separate
+            pyi_cache = black.read_cache(black.DEFAULT_LINE_LENGTH, py36_mode)
+            normal_cache = black.read_cache(black.DEFAULT_LINE_LENGTH, 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", "--py36"], input=source)
+        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"]:
+            result = CliRunner().invoke(black.main, ["-", option, "**()(!!*)"])
+            self.assertEqual(result.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)  # type: ignore
+                if nl == "\n":
+                    self.assertNotIn(b"\r\n", updated_contents)  # type: ignore
+
+    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("`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}")
+
 
-if __name__ == '__main__':
-    unittest.main()
+if __name__ == "__main__":
+    unittest.main(module="test_black")