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vim: Parse skip_magic_trailing_comma from pyproject.toml (#2613)
[etc/vim.git] / tests / util.py
1 import os
2 import sys
3 import unittest
4 from contextlib import contextmanager
5 from functools import partial
6 from pathlib import Path
7 from typing import Any, Iterator, List, Optional, Tuple
8
9 import black
10 from black.debug import DebugVisitor
11 from black.mode import TargetVersion
12 from black.output import diff, err, out
13
14 THIS_DIR = Path(__file__).parent
15 DATA_DIR = THIS_DIR / "data"
16 PROJECT_ROOT = THIS_DIR.parent
17 EMPTY_LINE = "# EMPTY LINE WITH WHITESPACE" + " (this comment will be removed)"
18 DETERMINISTIC_HEADER = "[Deterministic header]"
19
20 PY36_VERSIONS = {
21     TargetVersion.PY36,
22     TargetVersion.PY37,
23     TargetVersion.PY38,
24     TargetVersion.PY39,
25 }
26
27 DEFAULT_MODE = black.Mode()
28 ff = partial(black.format_file_in_place, mode=DEFAULT_MODE, fast=True)
29 fs = partial(black.format_str, mode=DEFAULT_MODE)
30
31
32 def _assert_format_equal(expected: str, actual: str) -> None:
33     if actual != expected and not os.environ.get("SKIP_AST_PRINT"):
34         bdv: DebugVisitor[Any]
35         out("Expected tree:", fg="green")
36         try:
37             exp_node = black.lib2to3_parse(expected)
38             bdv = DebugVisitor()
39             list(bdv.visit(exp_node))
40         except Exception as ve:
41             err(str(ve))
42         out("Actual tree:", fg="red")
43         try:
44             exp_node = black.lib2to3_parse(actual)
45             bdv = DebugVisitor()
46             list(bdv.visit(exp_node))
47         except Exception as ve:
48             err(str(ve))
49
50     if actual != expected:
51         out(diff(expected, actual, "expected", "actual"))
52
53     assert actual == expected
54
55
56 def assert_format(
57     source: str,
58     expected: str,
59     mode: black.Mode = DEFAULT_MODE,
60     *,
61     fast: bool = False,
62     minimum_version: Optional[Tuple[int, int]] = None,
63 ) -> None:
64     """Convenience function to check that Black formats as expected.
65
66     You can pass @minimum_version if you're passing code with newer syntax to guard
67     safety guards so they don't just crash with a SyntaxError. Please note this is
68     separate from TargetVerson Mode configuration.
69     """
70     actual = black.format_str(source, mode=mode)
71     _assert_format_equal(expected, actual)
72     # It's not useful to run safety checks if we're expecting no changes anyway. The
73     # assertion right above will raise if reality does actually make changes. This just
74     # avoids wasted CPU cycles.
75     if not fast and source != expected:
76         # Unfortunately the AST equivalence check relies on the built-in ast module
77         # being able to parse the code being formatted. This doesn't always work out
78         # when checking modern code on older versions.
79         if minimum_version is None or sys.version_info >= minimum_version:
80             black.assert_equivalent(source, actual)
81         black.assert_stable(source, actual, mode=mode)
82
83
84 def dump_to_stderr(*output: str) -> str:
85     return "\n" + "\n".join(output) + "\n"
86
87
88 class BlackBaseTestCase(unittest.TestCase):
89     def assertFormatEqual(self, expected: str, actual: str) -> None:
90         _assert_format_equal(expected, actual)
91
92
93 def read_data(name: str, data: bool = True) -> Tuple[str, str]:
94     """read_data('test_name') -> 'input', 'output'"""
95     if not name.endswith((".py", ".pyi", ".out", ".diff")):
96         name += ".py"
97     base_dir = DATA_DIR if data else PROJECT_ROOT
98     return read_data_from_file(base_dir / name)
99
100
101 def read_data_from_file(file_name: Path) -> Tuple[str, str]:
102     with open(file_name, "r", encoding="utf8") as test:
103         lines = test.readlines()
104     _input: List[str] = []
105     _output: List[str] = []
106     result = _input
107     for line in lines:
108         line = line.replace(EMPTY_LINE, "")
109         if line.rstrip() == "# output":
110             result = _output
111             continue
112
113         result.append(line)
114     if _input and not _output:
115         # If there's no output marker, treat the entire file as already pre-formatted.
116         _output = _input[:]
117     return "".join(_input).strip() + "\n", "".join(_output).strip() + "\n"
118
119
120 @contextmanager
121 def change_directory(path: Path) -> Iterator[None]:
122     """Context manager to temporarily chdir to a different directory."""
123     previous_dir = os.getcwd()
124     try:
125         os.chdir(path)
126         yield
127     finally:
128         os.chdir(previous_dir)