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[etc/vim.git] / tests / util.py
1 import os
2 import sys
3 import unittest
4 from contextlib import contextmanager
5 from dataclasses import replace
6 from functools import partial
7 from pathlib import Path
8 from typing import Any, Iterator, List, Optional, Tuple
9
10 import black
11 from black.debug import DebugVisitor
12 from black.mode import TargetVersion
13 from black.output import diff, err, out
14
15 PYTHON_SUFFIX = ".py"
16 ALLOWED_SUFFIXES = (PYTHON_SUFFIX, ".pyi", ".out", ".diff", ".ipynb")
17
18 THIS_DIR = Path(__file__).parent
19 DATA_DIR = THIS_DIR / "data"
20 PROJECT_ROOT = THIS_DIR.parent
21 EMPTY_LINE = "# EMPTY LINE WITH WHITESPACE" + " (this comment will be removed)"
22 DETERMINISTIC_HEADER = "[Deterministic header]"
23
24 PY36_VERSIONS = {
25     TargetVersion.PY36,
26     TargetVersion.PY37,
27     TargetVersion.PY38,
28     TargetVersion.PY39,
29 }
30
31 DEFAULT_MODE = black.Mode()
32 ff = partial(black.format_file_in_place, mode=DEFAULT_MODE, fast=True)
33 fs = partial(black.format_str, mode=DEFAULT_MODE)
34
35
36 def _assert_format_equal(expected: str, actual: str) -> None:
37     if actual != expected and not os.environ.get("SKIP_AST_PRINT"):
38         bdv: DebugVisitor[Any]
39         out("Expected tree:", fg="green")
40         try:
41             exp_node = black.lib2to3_parse(expected)
42             bdv = DebugVisitor()
43             list(bdv.visit(exp_node))
44         except Exception as ve:
45             err(str(ve))
46         out("Actual tree:", fg="red")
47         try:
48             exp_node = black.lib2to3_parse(actual)
49             bdv = DebugVisitor()
50             list(bdv.visit(exp_node))
51         except Exception as ve:
52             err(str(ve))
53
54     if actual != expected:
55         out(diff(expected, actual, "expected", "actual"))
56
57     assert actual == expected
58
59
60 class FormatFailure(Exception):
61     """Used to wrap failures when assert_format() runs in an extra mode."""
62
63
64 def assert_format(
65     source: str,
66     expected: str,
67     mode: black.Mode = DEFAULT_MODE,
68     *,
69     fast: bool = False,
70     minimum_version: Optional[Tuple[int, int]] = None,
71 ) -> None:
72     """Convenience function to check that Black formats as expected.
73
74     You can pass @minimum_version if you're passing code with newer syntax to guard
75     safety guards so they don't just crash with a SyntaxError. Please note this is
76     separate from TargetVerson Mode configuration.
77     """
78     _assert_format_inner(
79         source, expected, mode, fast=fast, minimum_version=minimum_version
80     )
81
82     # For both preview and non-preview tests, ensure that Black doesn't crash on
83     # this code, but don't pass "expected" because the precise output may differ.
84     try:
85         _assert_format_inner(
86             source,
87             None,
88             replace(mode, preview=not mode.preview),
89             fast=fast,
90             minimum_version=minimum_version,
91         )
92     except Exception as e:
93         text = "non-preview" if mode.preview else "preview"
94         raise FormatFailure(
95             f"Black crashed formatting this case in {text} mode."
96         ) from e
97     # Similarly, setting line length to 1 is a good way to catch
98     # stability bugs. But only in non-preview mode because preview mode
99     # currently has a lot of line length 1 bugs.
100     try:
101         _assert_format_inner(
102             source,
103             None,
104             replace(mode, preview=False, line_length=1),
105             fast=fast,
106             minimum_version=minimum_version,
107         )
108     except Exception as e:
109         raise FormatFailure(
110             "Black crashed formatting this case with line-length set to 1."
111         ) from e
112
113
114 def _assert_format_inner(
115     source: str,
116     expected: Optional[str] = None,
117     mode: black.Mode = DEFAULT_MODE,
118     *,
119     fast: bool = False,
120     minimum_version: Optional[Tuple[int, int]] = None,
121 ) -> None:
122     actual = black.format_str(source, mode=mode)
123     if expected is not None:
124         _assert_format_equal(expected, actual)
125     # It's not useful to run safety checks if we're expecting no changes anyway. The
126     # assertion right above will raise if reality does actually make changes. This just
127     # avoids wasted CPU cycles.
128     if not fast and source != actual:
129         # Unfortunately the AST equivalence check relies on the built-in ast module
130         # being able to parse the code being formatted. This doesn't always work out
131         # when checking modern code on older versions.
132         if minimum_version is None or sys.version_info >= minimum_version:
133             black.assert_equivalent(source, actual)
134         black.assert_stable(source, actual, mode=mode)
135
136
137 def dump_to_stderr(*output: str) -> str:
138     return "\n" + "\n".join(output) + "\n"
139
140
141 class BlackBaseTestCase(unittest.TestCase):
142     def assertFormatEqual(self, expected: str, actual: str) -> None:
143         _assert_format_equal(expected, actual)
144
145
146 def get_base_dir(data: bool) -> Path:
147     return DATA_DIR if data else PROJECT_ROOT
148
149
150 def all_data_cases(subdir_name: str, data: bool = True) -> List[str]:
151     cases_dir = get_base_dir(data) / subdir_name
152     assert cases_dir.is_dir()
153     return [case_path.stem for case_path in cases_dir.iterdir()]
154
155
156 def get_case_path(
157     subdir_name: str, name: str, data: bool = True, suffix: str = PYTHON_SUFFIX
158 ) -> Path:
159     """Get case path from name"""
160     case_path = get_base_dir(data) / subdir_name / name
161     if not name.endswith(ALLOWED_SUFFIXES):
162         case_path = case_path.with_suffix(suffix)
163     assert case_path.is_file(), f"{case_path} is not a file."
164     return case_path
165
166
167 def read_data(subdir_name: str, name: str, data: bool = True) -> Tuple[str, str]:
168     """read_data('test_name') -> 'input', 'output'"""
169     return read_data_from_file(get_case_path(subdir_name, name, data))
170
171
172 def read_data_from_file(file_name: Path) -> Tuple[str, str]:
173     with open(file_name, "r", encoding="utf8") as test:
174         lines = test.readlines()
175     _input: List[str] = []
176     _output: List[str] = []
177     result = _input
178     for line in lines:
179         line = line.replace(EMPTY_LINE, "")
180         if line.rstrip() == "# output":
181             result = _output
182             continue
183
184         result.append(line)
185     if _input and not _output:
186         # If there's no output marker, treat the entire file as already pre-formatted.
187         _output = _input[:]
188     return "".join(_input).strip() + "\n", "".join(_output).strip() + "\n"
189
190
191 def read_jupyter_notebook(subdir_name: str, name: str, data: bool = True) -> str:
192     return read_jupyter_notebook_from_file(
193         get_case_path(subdir_name, name, data, suffix=".ipynb")
194     )
195
196
197 def read_jupyter_notebook_from_file(file_name: Path) -> str:
198     with open(file_name, mode="rb") as fd:
199         content_bytes = fd.read()
200     return content_bytes.decode()
201
202
203 @contextmanager
204 def change_directory(path: Path) -> Iterator[None]:
205     """Context manager to temporarily chdir to a different directory."""
206     previous_dir = os.getcwd()
207     try:
208         os.chdir(path)
209         yield
210     finally:
211         os.chdir(previous_dir)