tests/test_black.py

   1 #!/usr/bin/env python3
   2 import asyncio
   3 from concurrent.futures import ThreadPoolExecutor
   4 from contextlib import contextmanager
   5 from functools import partial
   6 from io import StringIO
   7 import os
   8 from pathlib import Path
   9 import sys
  10 from tempfile import TemporaryDirectory
  11 from typing import Any, List, Tuple, Iterator
  12 import unittest
  13 from unittest.mock import patch
  14
  15 from click import unstyle
  16 from click.testing import CliRunner
  17
  18 import black
  19
  20 ll = 88
  21 ff = partial(black.format_file_in_place, line_length=ll, fast=True)
  22 fs = partial(black.format_str, line_length=ll)
  23 THIS_FILE = Path(__file__)
  24 THIS_DIR = THIS_FILE.parent
  25 EMPTY_LINE = "# EMPTY LINE WITH WHITESPACE" + " (this comment will be removed)"
  26
  27
  28 def dump_to_stderr(*output: str) -> str:
  29     return "\n" + "\n".join(output) + "\n"
  30
  31
  32 def read_data(name: str) -> Tuple[str, str]:
  33     """read_data('test_name') -> 'input', 'output'"""
  34     if not name.endswith((".py", ".out", ".diff")):
  35         name += ".py"
  36     _input: List[str] = []
  37     _output: List[str] = []
  38     with open(THIS_DIR / name, "r", encoding="utf8") as test:
  39         lines = test.readlines()
  40     result = _input
  41     for line in lines:
  42         line = line.replace(EMPTY_LINE, "")
  43         if line.rstrip() == "# output":
  44             result = _output
  45             continue
  46
  47         result.append(line)
  48     if _input and not _output:
  49         # If there's no output marker, treat the entire file as already pre-formatted.
  50         _output = _input[:]
  51     return "".join(_input).strip() + "\n", "".join(_output).strip() + "\n"
  52
  53
  54 @contextmanager
  55 def cache_dir(exists: bool = True) -> Iterator[Path]:
  56     with TemporaryDirectory() as workspace:
  57         cache_dir = Path(workspace)
  58         if not exists:
  59             cache_dir = cache_dir / "new"
  60         cache_file = cache_dir / "cache.pkl"
  61         with patch("black.CACHE_DIR", cache_dir), patch("black.CACHE_FILE", cache_file):
  62             yield cache_dir
  63
  64
  65 @contextmanager
  66 def event_loop(close: bool) -> Iterator[None]:
  67     policy = asyncio.get_event_loop_policy()
  68     old_loop = policy.get_event_loop()
  69     loop = policy.new_event_loop()
  70     asyncio.set_event_loop(loop)
  71     try:
  72         yield
  73
  74     finally:
  75         policy.set_event_loop(old_loop)
  76         if close:
  77             loop.close()
  78
  79
  80 class BlackTestCase(unittest.TestCase):
  81     maxDiff = None
  82
  83     def assertFormatEqual(self, expected: str, actual: str) -> None:
  84         if actual != expected and not os.environ.get("SKIP_AST_PRINT"):
  85             bdv: black.DebugVisitor[Any]
  86             black.out("Expected tree:", fg="green")
  87             try:
  88                 exp_node = black.lib2to3_parse(expected)
  89                 bdv = black.DebugVisitor()
  90                 list(bdv.visit(exp_node))
  91             except Exception as ve:
  92                 black.err(str(ve))
  93             black.out("Actual tree:", fg="red")
  94             try:
  95                 exp_node = black.lib2to3_parse(actual)
  96                 bdv = black.DebugVisitor()
  97                 list(bdv.visit(exp_node))
  98             except Exception as ve:
  99                 black.err(str(ve))
 100         self.assertEqual(expected, actual)
 101
 102     @patch("black.dump_to_file", dump_to_stderr)
 103     def test_self(self) -> None:
 104         source, expected = read_data("test_black")
 105         actual = fs(source)
 106         self.assertFormatEqual(expected, actual)
 107         black.assert_equivalent(source, actual)
 108         black.assert_stable(source, actual, line_length=ll)
 109         self.assertFalse(ff(THIS_FILE))
 110
 111     @patch("black.dump_to_file", dump_to_stderr)
 112     def test_black(self) -> None:
 113         source, expected = read_data("../black")
 114         actual = fs(source)
 115         self.assertFormatEqual(expected, actual)
 116         black.assert_equivalent(source, actual)
 117         black.assert_stable(source, actual, line_length=ll)
 118         self.assertFalse(ff(THIS_DIR / ".." / "black.py"))
 119
 120     def test_piping(self) -> None:
 121         source, expected = read_data("../black")
 122         hold_stdin, hold_stdout = sys.stdin, sys.stdout
 123         try:
 124             sys.stdin, sys.stdout = StringIO(source), StringIO()
 125             sys.stdin.name = "<stdin>"
 126             black.format_stdin_to_stdout(
 127                 line_length=ll, fast=True, write_back=black.WriteBack.YES
 128             )
 129             sys.stdout.seek(0)
 130             actual = sys.stdout.read()
 131         finally:
 132             sys.stdin, sys.stdout = hold_stdin, hold_stdout
 133         self.assertFormatEqual(expected, actual)
 134         black.assert_equivalent(source, actual)
 135         black.assert_stable(source, actual, line_length=ll)
 136
 137     def test_piping_diff(self) -> None:
 138         source, _ = read_data("expression.py")
 139         expected, _ = read_data("expression.diff")
 140         hold_stdin, hold_stdout = sys.stdin, sys.stdout
 141         try:
 142             sys.stdin, sys.stdout = StringIO(source), StringIO()
 143             sys.stdin.name = "<stdin>"
 144             black.format_stdin_to_stdout(
 145                 line_length=ll, fast=True, write_back=black.WriteBack.DIFF
 146             )
 147             sys.stdout.seek(0)
 148             actual = sys.stdout.read()
 149         finally:
 150             sys.stdin, sys.stdout = hold_stdin, hold_stdout
 151         actual = actual.rstrip() + "\n"  # the diff output has a trailing space
 152         self.assertEqual(expected, actual)
 153
 154     @patch("black.dump_to_file", dump_to_stderr)
 155     def test_setup(self) -> None:
 156         source, expected = read_data("../setup")
 157         actual = fs(source)
 158         self.assertFormatEqual(expected, actual)
 159         black.assert_equivalent(source, actual)
 160         black.assert_stable(source, actual, line_length=ll)
 161         self.assertFalse(ff(THIS_DIR / ".." / "setup.py"))
 162
 163     @patch("black.dump_to_file", dump_to_stderr)
 164     def test_function(self) -> None:
 165         source, expected = read_data("function")
 166         actual = fs(source)
 167         self.assertFormatEqual(expected, actual)
 168         black.assert_equivalent(source, actual)
 169         black.assert_stable(source, actual, line_length=ll)
 170
 171     @patch("black.dump_to_file", dump_to_stderr)
 172     def test_expression(self) -> None:
 173         source, expected = read_data("expression")
 174         actual = fs(source)
 175         self.assertFormatEqual(expected, actual)
 176         black.assert_equivalent(source, actual)
 177         black.assert_stable(source, actual, line_length=ll)
 178
 179     def test_expression_ff(self) -> None:
 180         source, expected = read_data("expression")
 181         tmp_file = Path(black.dump_to_file(source))
 182         try:
 183             self.assertTrue(ff(tmp_file, write_back=black.WriteBack.YES))
 184             with open(tmp_file, encoding="utf8") as f:
 185                 actual = f.read()
 186         finally:
 187             os.unlink(tmp_file)
 188         self.assertFormatEqual(expected, actual)
 189         with patch("black.dump_to_file", dump_to_stderr):
 190             black.assert_equivalent(source, actual)
 191             black.assert_stable(source, actual, line_length=ll)
 192
 193     def test_expression_diff(self) -> None:
 194         source, _ = read_data("expression.py")
 195         expected, _ = read_data("expression.diff")
 196         tmp_file = Path(black.dump_to_file(source))
 197         hold_stdout = sys.stdout
 198         try:
 199             sys.stdout = StringIO()
 200             self.assertTrue(ff(tmp_file, write_back=black.WriteBack.DIFF))
 201             sys.stdout.seek(0)
 202             actual = sys.stdout.read()
 203             actual = actual.replace(str(tmp_file), "<stdin>")
 204         finally:
 205             sys.stdout = hold_stdout
 206             os.unlink(tmp_file)
 207         actual = actual.rstrip() + "\n"  # the diff output has a trailing space
 208         if expected != actual:
 209             dump = black.dump_to_file(actual)
 210             msg = (
 211                 f"Expected diff isn't equal to the actual. If you made changes "
 212                 f"to expression.py and this is an anticipated difference, "
 213                 f"overwrite tests/expression.diff with {dump}"
 214             )
 215             self.assertEqual(expected, actual, msg)
 216
 217     @patch("black.dump_to_file", dump_to_stderr)
 218     def test_fstring(self) -> None:
 219         source, expected = read_data("fstring")
 220         actual = fs(source)
 221         self.assertFormatEqual(expected, actual)
 222         black.assert_equivalent(source, actual)
 223         black.assert_stable(source, actual, line_length=ll)
 224
 225     @patch("black.dump_to_file", dump_to_stderr)
 226     def test_string_quotes(self) -> None:
 227         source, expected = read_data("string_quotes")
 228         actual = fs(source)
 229         self.assertFormatEqual(expected, actual)
 230         black.assert_equivalent(source, actual)
 231         black.assert_stable(source, actual, line_length=ll)
 232
 233     @patch("black.dump_to_file", dump_to_stderr)
 234     def test_comments(self) -> None:
 235         source, expected = read_data("comments")
 236         actual = fs(source)
 237         self.assertFormatEqual(expected, actual)
 238         black.assert_equivalent(source, actual)
 239         black.assert_stable(source, actual, line_length=ll)
 240
 241     @patch("black.dump_to_file", dump_to_stderr)
 242     def test_comments2(self) -> None:
 243         source, expected = read_data("comments2")
 244         actual = fs(source)
 245         self.assertFormatEqual(expected, actual)
 246         black.assert_equivalent(source, actual)
 247         black.assert_stable(source, actual, line_length=ll)
 248
 249     @patch("black.dump_to_file", dump_to_stderr)
 250     def test_comments3(self) -> None:
 251         source, expected = read_data("comments3")
 252         actual = fs(source)
 253         self.assertFormatEqual(expected, actual)
 254         black.assert_equivalent(source, actual)
 255         black.assert_stable(source, actual, line_length=ll)
 256
 257     @patch("black.dump_to_file", dump_to_stderr)
 258     def test_comments4(self) -> None:
 259         source, expected = read_data("comments4")
 260         actual = fs(source)
 261         self.assertFormatEqual(expected, actual)
 262         black.assert_equivalent(source, actual)
 263         black.assert_stable(source, actual, line_length=ll)
 264
 265     @patch("black.dump_to_file", dump_to_stderr)
 266     def test_comments5(self) -> None:
 267         source, expected = read_data("comments5")
 268         actual = fs(source)
 269         self.assertFormatEqual(expected, actual)
 270         black.assert_equivalent(source, actual)
 271         black.assert_stable(source, actual, line_length=ll)
 272
 273     @patch("black.dump_to_file", dump_to_stderr)
 274     def test_cantfit(self) -> None:
 275         source, expected = read_data("cantfit")
 276         actual = fs(source)
 277         self.assertFormatEqual(expected, actual)
 278         black.assert_equivalent(source, actual)
 279         black.assert_stable(source, actual, line_length=ll)
 280
 281     @patch("black.dump_to_file", dump_to_stderr)
 282     def test_import_spacing(self) -> None:
 283         source, expected = read_data("import_spacing")
 284         actual = fs(source)
 285         self.assertFormatEqual(expected, actual)
 286         black.assert_equivalent(source, actual)
 287         black.assert_stable(source, actual, line_length=ll)
 288
 289     @patch("black.dump_to_file", dump_to_stderr)
 290     def test_composition(self) -> None:
 291         source, expected = read_data("composition")
 292         actual = fs(source)
 293         self.assertFormatEqual(expected, actual)
 294         black.assert_equivalent(source, actual)
 295         black.assert_stable(source, actual, line_length=ll)
 296
 297     @patch("black.dump_to_file", dump_to_stderr)
 298     def test_empty_lines(self) -> None:
 299         source, expected = read_data("empty_lines")
 300         actual = fs(source)
 301         self.assertFormatEqual(expected, actual)
 302         black.assert_equivalent(source, actual)
 303         black.assert_stable(source, actual, line_length=ll)
 304
 305     @patch("black.dump_to_file", dump_to_stderr)
 306     def test_python2(self) -> None:
 307         source, expected = read_data("python2")
 308         actual = fs(source)
 309         self.assertFormatEqual(expected, actual)
 310         # black.assert_equivalent(source, actual)
 311         black.assert_stable(source, actual, line_length=ll)
 312
 313     @patch("black.dump_to_file", dump_to_stderr)
 314     def test_fmtonoff(self) -> None:
 315         source, expected = read_data("fmtonoff")
 316         actual = fs(source)
 317         self.assertFormatEqual(expected, actual)
 318         black.assert_equivalent(source, actual)
 319         black.assert_stable(source, actual, line_length=ll)
 320
 321     def test_report(self) -> None:
 322         report = black.Report()
 323         out_lines = []
 324         err_lines = []
 325
 326         def out(msg: str, **kwargs: Any) -> None:
 327             out_lines.append(msg)
 328
 329         def err(msg: str, **kwargs: Any) -> None:
 330             err_lines.append(msg)
 331
 332         with patch("black.out", out), patch("black.err", err):
 333             report.done(Path("f1"), black.Changed.NO)
 334             self.assertEqual(len(out_lines), 1)
 335             self.assertEqual(len(err_lines), 0)
 336             self.assertEqual(out_lines[-1], "f1 already well formatted, good job.")
 337             self.assertEqual(unstyle(str(report)), "1 file left unchanged.")
 338             self.assertEqual(report.return_code, 0)
 339             report.done(Path("f2"), black.Changed.YES)
 340             self.assertEqual(len(out_lines), 2)
 341             self.assertEqual(len(err_lines), 0)
 342             self.assertEqual(out_lines[-1], "reformatted f2")
 343             self.assertEqual(
 344                 unstyle(str(report)), "1 file reformatted, 1 file left unchanged."
 345             )
 346             report.done(Path("f3"), black.Changed.CACHED)
 347             self.assertEqual(len(out_lines), 3)
 348             self.assertEqual(len(err_lines), 0)
 349             self.assertEqual(
 350                 out_lines[-1], "f3 wasn't modified on disk since last run."
 351             )
 352             self.assertEqual(
 353                 unstyle(str(report)), "1 file reformatted, 2 files left unchanged."
 354             )
 355             self.assertEqual(report.return_code, 0)
 356             report.check = True
 357             self.assertEqual(report.return_code, 1)
 358             report.check = False
 359             report.failed(Path("e1"), "boom")
 360             self.assertEqual(len(out_lines), 3)
 361             self.assertEqual(len(err_lines), 1)
 362             self.assertEqual(err_lines[-1], "error: cannot format e1: boom")
 363             self.assertEqual(
 364                 unstyle(str(report)),
 365                 "1 file reformatted, 2 files left unchanged, "
 366                 "1 file failed to reformat.",
 367             )
 368             self.assertEqual(report.return_code, 123)
 369             report.done(Path("f3"), black.Changed.YES)
 370             self.assertEqual(len(out_lines), 4)
 371             self.assertEqual(len(err_lines), 1)
 372             self.assertEqual(out_lines[-1], "reformatted f3")
 373             self.assertEqual(
 374                 unstyle(str(report)),
 375                 "2 files reformatted, 2 files left unchanged, "
 376                 "1 file failed to reformat.",
 377             )
 378             self.assertEqual(report.return_code, 123)
 379             report.failed(Path("e2"), "boom")
 380             self.assertEqual(len(out_lines), 4)
 381             self.assertEqual(len(err_lines), 2)
 382             self.assertEqual(err_lines[-1], "error: cannot format e2: boom")
 383             self.assertEqual(
 384                 unstyle(str(report)),
 385                 "2 files reformatted, 2 files left unchanged, "
 386                 "2 files failed to reformat.",
 387             )
 388             self.assertEqual(report.return_code, 123)
 389             report.done(Path("f4"), black.Changed.NO)
 390             self.assertEqual(len(out_lines), 5)
 391             self.assertEqual(len(err_lines), 2)
 392             self.assertEqual(out_lines[-1], "f4 already well formatted, good job.")
 393             self.assertEqual(
 394                 unstyle(str(report)),
 395                 "2 files reformatted, 3 files left unchanged, "
 396                 "2 files failed to reformat.",
 397             )
 398             self.assertEqual(report.return_code, 123)
 399             report.check = True
 400             self.assertEqual(
 401                 unstyle(str(report)),
 402                 "2 files would be reformatted, 3 files would be left unchanged, "
 403                 "2 files would fail to reformat.",
 404             )
 405
 406     def test_is_python36(self) -> None:
 407         node = black.lib2to3_parse("def f(*, arg): ...\n")
 408         self.assertFalse(black.is_python36(node))
 409         node = black.lib2to3_parse("def f(*, arg,): ...\n")
 410         self.assertTrue(black.is_python36(node))
 411         node = black.lib2to3_parse("def f(*, arg): f'string'\n")
 412         self.assertTrue(black.is_python36(node))
 413         source, expected = read_data("function")
 414         node = black.lib2to3_parse(source)
 415         self.assertTrue(black.is_python36(node))
 416         node = black.lib2to3_parse(expected)
 417         self.assertTrue(black.is_python36(node))
 418         source, expected = read_data("expression")
 419         node = black.lib2to3_parse(source)
 420         self.assertFalse(black.is_python36(node))
 421         node = black.lib2to3_parse(expected)
 422         self.assertFalse(black.is_python36(node))
 423
 424     def test_debug_visitor(self) -> None:
 425         source, _ = read_data("debug_visitor.py")
 426         expected, _ = read_data("debug_visitor.out")
 427         out_lines = []
 428         err_lines = []
 429
 430         def out(msg: str, **kwargs: Any) -> None:
 431             out_lines.append(msg)
 432
 433         def err(msg: str, **kwargs: Any) -> None:
 434             err_lines.append(msg)
 435
 436         with patch("black.out", out), patch("black.err", err):
 437             black.DebugVisitor.show(source)
 438         actual = "\n".join(out_lines) + "\n"
 439         log_name = ""
 440         if expected != actual:
 441             log_name = black.dump_to_file(*out_lines)
 442         self.assertEqual(
 443             expected,
 444             actual,
 445             f"AST print out is different. Actual version dumped to {log_name}",
 446         )
 447
 448     def test_format_file_contents(self) -> None:
 449         empty = ""
 450         with self.assertRaises(black.NothingChanged):
 451             black.format_file_contents(empty, line_length=ll, fast=False)
 452         just_nl = "\n"
 453         with self.assertRaises(black.NothingChanged):
 454             black.format_file_contents(just_nl, line_length=ll, fast=False)
 455         same = "l = [1, 2, 3]\n"
 456         with self.assertRaises(black.NothingChanged):
 457             black.format_file_contents(same, line_length=ll, fast=False)
 458         different = "l = [1,2,3]"
 459         expected = same
 460         actual = black.format_file_contents(different, line_length=ll, fast=False)
 461         self.assertEqual(expected, actual)
 462         invalid = "return if you can"
 463         with self.assertRaises(ValueError) as e:
 464             black.format_file_contents(invalid, line_length=ll, fast=False)
 465         self.assertEqual(str(e.exception), "Cannot parse: 1:7: return if you can")
 466
 467     def test_endmarker(self) -> None:
 468         n = black.lib2to3_parse("\n")
 469         self.assertEqual(n.type, black.syms.file_input)
 470         self.assertEqual(len(n.children), 1)
 471         self.assertEqual(n.children[0].type, black.token.ENDMARKER)
 472
 473     @unittest.skipIf(os.environ.get("SKIP_AST_PRINT"), "user set SKIP_AST_PRINT")
 474     def test_assertFormatEqual(self) -> None:
 475         out_lines = []
 476         err_lines = []
 477
 478         def out(msg: str, **kwargs: Any) -> None:
 479             out_lines.append(msg)
 480
 481         def err(msg: str, **kwargs: Any) -> None:
 482             err_lines.append(msg)
 483
 484         with patch("black.out", out), patch("black.err", err):
 485             with self.assertRaises(AssertionError):
 486                 self.assertFormatEqual("l = [1, 2, 3]", "l = [1, 2, 3,]")
 487
 488         out_str = "".join(out_lines)
 489         self.assertTrue("Expected tree:" in out_str)
 490         self.assertTrue("Actual tree:" in out_str)
 491         self.assertEqual("".join(err_lines), "")
 492
 493     def test_cache_broken_file(self) -> None:
 494         with cache_dir() as workspace:
 495             with black.CACHE_FILE.open("w") as fobj:
 496                 fobj.write("this is not a pickle")
 497             self.assertEqual(black.read_cache(), {})
 498             src = (workspace / "test.py").resolve()
 499             with src.open("w") as fobj:
 500                 fobj.write("print('hello')")
 501             result = CliRunner().invoke(black.main, [str(src)])
 502             self.assertEqual(result.exit_code, 0)
 503             cache = black.read_cache()
 504             self.assertIn(src, cache)
 505
 506     def test_cache_single_file_already_cached(self) -> None:
 507         with cache_dir() as workspace:
 508             src = (workspace / "test.py").resolve()
 509             with src.open("w") as fobj:
 510                 fobj.write("print('hello')")
 511             black.write_cache({}, [src])
 512             result = CliRunner().invoke(black.main, [str(src)])
 513             self.assertEqual(result.exit_code, 0)
 514             with src.open("r") as fobj:
 515                 self.assertEqual(fobj.read(), "print('hello')")
 516
 517     @event_loop(close=False)
 518     def test_cache_multiple_files(self) -> None:
 519         with cache_dir() as workspace, patch(
 520             "black.ProcessPoolExecutor", new=ThreadPoolExecutor
 521         ):
 522             one = (workspace / "one.py").resolve()
 523             with one.open("w") as fobj:
 524                 fobj.write("print('hello')")
 525             two = (workspace / "two.py").resolve()
 526             with two.open("w") as fobj:
 527                 fobj.write("print('hello')")
 528             black.write_cache({}, [one])
 529             result = CliRunner().invoke(black.main, [str(workspace)])
 530             self.assertEqual(result.exit_code, 0)
 531             with one.open("r") as fobj:
 532                 self.assertEqual(fobj.read(), "print('hello')")
 533             with two.open("r") as fobj:
 534                 self.assertEqual(fobj.read(), 'print("hello")\n')
 535             cache = black.read_cache()
 536             self.assertIn(one, cache)
 537             self.assertIn(two, cache)
 538
 539     def test_no_cache_when_writeback_diff(self) -> None:
 540         with cache_dir() as workspace:
 541             src = (workspace / "test.py").resolve()
 542             with src.open("w") as fobj:
 543                 fobj.write("print('hello')")
 544             result = CliRunner().invoke(black.main, [str(src), "--diff"])
 545             self.assertEqual(result.exit_code, 0)
 546             self.assertFalse(black.CACHE_FILE.exists())
 547
 548     def test_no_cache_when_stdin(self) -> None:
 549         with cache_dir():
 550             result = CliRunner().invoke(black.main, ["-"], input="print('hello')")
 551             self.assertEqual(result.exit_code, 0)
 552             self.assertFalse(black.CACHE_FILE.exists())
 553
 554     def test_read_cache_no_cachefile(self) -> None:
 555         with cache_dir():
 556             self.assertEqual(black.read_cache(), {})
 557
 558     def test_write_cache_read_cache(self) -> None:
 559         with cache_dir() as workspace:
 560             src = (workspace / "test.py").resolve()
 561             src.touch()
 562             black.write_cache({}, [src])
 563             cache = black.read_cache()
 564             self.assertIn(src, cache)
 565             self.assertEqual(cache[src], black.get_cache_info(src))
 566
 567     def test_filter_cached(self) -> None:
 568         with TemporaryDirectory() as workspace:
 569             path = Path(workspace)
 570             uncached = (path / "uncached").resolve()
 571             cached = (path / "cached").resolve()
 572             cached_but_changed = (path / "changed").resolve()
 573             uncached.touch()
 574             cached.touch()
 575             cached_but_changed.touch()
 576             cache = {cached: black.get_cache_info(cached), cached_but_changed: (0.0, 0)}
 577             todo, done = black.filter_cached(
 578                 cache, [uncached, cached, cached_but_changed]
 579             )
 580             self.assertEqual(todo, [uncached, cached_but_changed])
 581             self.assertEqual(done, [cached])
 582
 583     def test_write_cache_creates_directory_if_needed(self) -> None:
 584         with cache_dir(exists=False) as workspace:
 585             self.assertFalse(workspace.exists())
 586             black.write_cache({}, [])
 587             self.assertTrue(workspace.exists())
 588
 589     @event_loop(close=False)
 590     def test_failed_formatting_does_not_get_cached(self) -> None:
 591         with cache_dir() as workspace, patch(
 592             "black.ProcessPoolExecutor", new=ThreadPoolExecutor
 593         ):
 594             failing = (workspace / "failing.py").resolve()
 595             with failing.open("w") as fobj:
 596                 fobj.write("not actually python")
 597             clean = (workspace / "clean.py").resolve()
 598             with clean.open("w") as fobj:
 599                 fobj.write('print("hello")\n')
 600             result = CliRunner().invoke(black.main, [str(workspace)])
 601             self.assertEqual(result.exit_code, 123)
 602             cache = black.read_cache()
 603             self.assertNotIn(failing, cache)
 604             self.assertIn(clean, cache)
 605
 606     def test_write_cache_write_fail(self) -> None:
 607         with cache_dir(), patch.object(Path, "open") as mock:
 608             mock.side_effect = OSError
 609             black.write_cache({}, [])
 610
 611     def test_check_diff_use_together(self) -> None:
 612         with cache_dir():
 613             # Files which will be reformatted.
 614             src1 = (THIS_DIR / "string_quotes.py").resolve()
 615             result = CliRunner().invoke(black.main, [str(src1), "--diff", "--check"])
 616             self.assertEqual(result.exit_code, 1)
 617
 618             # Files which will not be reformatted.
 619             src2 = (THIS_DIR / "composition.py").resolve()
 620             result = CliRunner().invoke(black.main, [str(src2), "--diff", "--check"])
 621             self.assertEqual(result.exit_code, 0)
 622
 623             # Multi file command.
 624             result = CliRunner().invoke(
 625                 black.main, [str(src1), str(src2), "--diff", "--check"]
 626             )
 627             self.assertEqual(result.exit_code, 1)
 628
 629     @patch("black.dump_to_file", dump_to_stderr)
 630     def test_comment_in_decorator(self) -> None:
 631         source, expected = read_data("comments6")
 632         actual = fs(source)
 633         self.assertFormatEqual(expected, actual)
 634         black.assert_equivalent(source, actual)
 635         black.assert_stable(source, actual, line_length=ll)
 636
 637
 638 if __name__ == "__main__":
 639     unittest.main()