Store pickles for 3.8.0a0

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

diff --git a/tests/test_black.py b/tests/test_black.py
index 1c22e54db7a03f5addb06bf98b13dad527401893..fc310690ccec649a339bad18b53e6d44ccd335c7 100644 (file)
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -1,14 +1,18 @@
 #!/usr/bin/env python3
 #!/usr/bin/env python3

+import asyncio
+from contextlib import contextmanager

 from functools import partial
 from io import StringIO
 import os
 from pathlib import Path
 import sys
 from functools import partial
 from io import StringIO
 import os
 from pathlib import Path
 import sys

-from typing import Any, List, Tuple
+from tempfile import TemporaryDirectory
+from typing import Any, List, Tuple, Iterator

 import unittest
 from unittest.mock import patch
 
 from click import unstyle
 import unittest
 from unittest.mock import patch
 
 from click import unstyle

+from click.testing import CliRunner

 
 import black
 
 
 import black
 


@@ -17,25 +21,25 @@ 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
 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:
 
 
 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]:
     """read_data('test_name') -> 'input', 'output'"""
 
 
 def read_data(name: str) -> Tuple[str, str]:
     """read_data('test_name') -> 'input', 'output'"""

-    if not name.endswith(('.py', '.out')):
-        name += '.py'
+    if not name.endswith((".py", ".out", ".diff")):
+        name += ".py"

     _input: List[str] = []
     _output: List[str] = []
     _input: List[str] = []
     _output: List[str] = []

-    with open(THIS_DIR / name, 'r', encoding='utf8') as test:
+    with open(THIS_DIR / name, "r", encoding="utf8") as test:

         lines = test.readlines()
     result = _input
     for line in lines:
         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
 
             result = _output
             continue
 


@@ -43,23 +47,49 @@ 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[:]
     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"
+        cache_file = cache_dir / "cache.pkl"
+        with patch("black.CACHE_DIR", cache_dir), patch("black.CACHE_FILE", cache_file):
+            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 BlackTestCase(unittest.TestCase):
     maxDiff = None
 
     def assertFormatEqual(self, expected: str, actual: str) -> None:
 
 
 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]
             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))
             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()
             try:
                 exp_node = black.lib2to3_parse(actual)
                 bdv = black.DebugVisitor()


@@ -70,7 +100,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_self(self) -> None:
 
     @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")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -79,20 +109,22 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_black(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_black(self) -> None:

-        source, expected = read_data('../black')
+        source, expected = read_data("../black")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, line_length=ll)
         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:
 
     def test_piping(self) -> None:

-        source, expected = read_data('../black')
+        source, expected = read_data("../black")

         hold_stdin, hold_stdout = sys.stdin, sys.stdout
         try:
             sys.stdin, sys.stdout = StringIO(source), StringIO()
         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.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.stdout.seek(0)
             actual = sys.stdout.read()
         finally:


@@ -101,18 +133,35 @@ class BlackTestCase(unittest.TestCase):
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, line_length=ll)
 
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, line_length=ll)
 

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

-        source, expected = read_data('../setup')
+        source, expected = read_data("../setup")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, line_length=ll)
         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'))
+        self.assertFalse(ff(THIS_DIR / ".." / "setup.py"))

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

-        source, expected = read_data('function')
+        source, expected = read_data("function")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -120,15 +169,61 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_expression(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_expression(self) -> None:

-        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)
 
         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))
+        hold_stdout = sys.stdout
+        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>")
+        finally:
+            sys.stdout = hold_stdout
+            os.unlink(tmp_file)
+        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:
     @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)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -136,7 +231,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments(self) -> None:

-        source, expected = read_data('comments')
+        source, expected = read_data("comments")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -144,7 +239,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments2(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments2(self) -> None:

-        source, expected = read_data('comments2')
+        source, expected = read_data("comments2")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -152,7 +247,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments3(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments3(self) -> None:

-        source, expected = read_data('comments3')
+        source, expected = read_data("comments3")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -160,7 +255,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments4(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_comments4(self) -> None:

-        source, expected = read_data('comments4')
+        source, expected = read_data("comments4")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -168,7 +263,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_cantfit(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_cantfit(self) -> None:

-        source, expected = read_data('cantfit')
+        source, expected = read_data("cantfit")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -176,7 +271,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_import_spacing(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_import_spacing(self) -> None:

-        source, expected = read_data('import_spacing')
+        source, expected = read_data("import_spacing")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -184,7 +279,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_composition(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_composition(self) -> None:

-        source, expected = read_data('composition')
+        source, expected = read_data("composition")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -192,7 +287,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_empty_lines(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_empty_lines(self) -> None:

-        source, expected = read_data('empty_lines')
+        source, expected = read_data("empty_lines")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -200,7 +295,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2(self) -> None:
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2(self) -> None:

-        source, expected = read_data('python2')
+        source, expected = read_data("python2")

         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         # black.assert_equivalent(source, actual)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         # black.assert_equivalent(source, actual)


@@ -208,7 +303,7 @@ class BlackTestCase(unittest.TestCase):
 
     @patch("black.dump_to_file", dump_to_stderr)
     def test_fmtonoff(self) -> None:
 
     @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)
         actual = fs(source)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)


@@ -226,68 +321,77 @@ class BlackTestCase(unittest.TestCase):
             err_lines.append(msg)
 
         with patch("black.out", out), patch("black.err", err):
             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(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)
             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(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(
+                out_lines[-1], "f3 wasn't modified on disk since last run."
+            )

             self.assertEqual(
             self.assertEqual(

-                unstyle(str(report)), '1 file reformatted, 1 file left unchanged.'
+                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
             )
             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(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)),
             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)
             )
             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(len(err_lines), 1)

-            self.assertEqual(out_lines[-1], 'reformatted f3')
+            self.assertEqual(out_lines[-1], "reformatted f3")

             self.assertEqual(
                 unstyle(str(report)),
             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)
             )
             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(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)),
             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)
             )
             self.assertEqual(report.return_code, 123)

-            report.done(Path('f4'), changed=False)
-            self.assertEqual(len(out_lines), 4)
+            report.done(Path("f4"), black.Changed.NO)
+            self.assertEqual(len(out_lines), 5)

             self.assertEqual(len(err_lines), 2)
             self.assertEqual(len(err_lines), 2)

-            self.assertEqual(out_lines[-1], 'f4 already well formatted, good job.')
+            self.assertEqual(out_lines[-1], "f4 already well formatted, good job.")

             self.assertEqual(
                 unstyle(str(report)),
             self.assertEqual(
                 unstyle(str(report)),

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

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

-                '2 files would be reformatted, 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_is_python36(self) -> None:
             )
 
     def test_is_python36(self) -> None:


@@ -297,20 +401,20 @@ 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))
         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))
         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_debug_visitor(self) -> None:
         node = black.lib2to3_parse(source)
         self.assertFalse(black.is_python36(node))
         node = black.lib2to3_parse(expected)
         self.assertFalse(black.is_python36(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 = []
 
         out_lines = []
         err_lines = []
 


@@ -322,8 +426,8 @@ class BlackTestCase(unittest.TestCase):
 
         with patch("black.out", out), patch("black.err", err):
             black.DebugVisitor.show(source)
 
         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(
         if expected != actual:
             log_name = black.dump_to_file(*out_lines)
         self.assertEqual(


@@ -332,6 +436,165 @@ class BlackTestCase(unittest.TestCase):
             f"AST print out is different. Actual version dumped to {log_name}",
         )
 
             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)

 
 

-if __name__ == '__main__':
+        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:
+        with cache_dir() as workspace:
+            with black.CACHE_FILE.open("w") as fobj:
+                fobj.write("this is not a pickle")
+            self.assertEqual(black.read_cache(), {})
+            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.assertIn(src, cache)
+
+    def test_cache_single_file_already_cached(self) -> None:
+        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)
+            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:
+            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)
+            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()
+            self.assertIn(one, cache)
+            self.assertIn(two, cache)
+
+    def test_no_cache_when_writeback_diff(self) -> None:
+        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())
+
+    def test_no_cache_when_stdin(self) -> None:
+        with cache_dir():
+            result = CliRunner().invoke(black.main, ["-"], input="print('hello')")
+            self.assertEqual(result.exit_code, 0)
+            self.assertFalse(black.CACHE_FILE.exists())
+
+    def test_read_cache_no_cachefile(self) -> None:
+        with cache_dir():
+            self.assertEqual(black.read_cache(), {})
+
+    def test_write_cache_read_cache(self) -> None:
+        with cache_dir() as workspace:
+            src = (workspace / "test.py").resolve()
+            src.touch()
+            black.write_cache({}, [src])
+            cache = black.read_cache()
+            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:
+        with cache_dir(exists=False) as workspace:
+            self.assertFalse(workspace.exists())
+            black.write_cache({}, [])
+            self.assertTrue(workspace.exists())
+
+    @event_loop(close=False)
+    def test_failed_formatting_does_not_get_cached(self) -> None:
+        with cache_dir() as workspace:
+            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.assertNotIn(failing, cache)
+            self.assertIn(clean, cache)
+
+    def test_write_cache_write_fail(self) -> None:
+        with cache_dir(), patch.object(Path, "open") as mock:
+            mock.side_effect = OSError
+            black.write_cache({}, [])
+
+
+if __name__ == "__main__":

     unittest.main()
     unittest.main()