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.
1 """Property-based tests for Black.
3 By Zac Hatfield-Dodds, based on my Hypothesmith tool for source code
4 generation. You can run this file with `python`, `pytest`, or (soon)
5 a coverage-guided fuzzer I'm working on.
11 from hypothesis import HealthCheck, given, settings
12 from hypothesis import strategies as st
15 from blib2to3.pgen2.tokenize import TokenError
18 # This test uses the Hypothesis and Hypothesmith libraries to generate random
19 # syntatically-valid Python source code and run Black in odd modes.
21 max_examples=1000, # roughly 1k tests/minute, or half that under coverage
22 derandomize=True, # deterministic mode to avoid CI flakiness
23 deadline=None, # ignore Hypothesis' health checks; we already know that
24 suppress_health_check=HealthCheck.all(), # this is slow and filter-heavy.
27 # Note that while Hypothesmith might generate code unlike that written by
28 # humans, it's a general test that should pass for any *valid* source code.
29 # (so e.g. running it against code scraped of the internet might also help)
30 src_contents=hypothesmith.from_grammar() | hypothesmith.from_node(),
31 # Using randomly-varied modes helps us to exercise less common code paths.
34 line_length=st.just(88) | st.integers(0, 200),
35 string_normalization=st.booleans(),
36 preview=st.booleans(),
38 magic_trailing_comma=st.booleans(),
41 def test_idempotent_any_syntatically_valid_python(
42 src_contents: str, mode: black.FileMode
44 # Before starting, let's confirm that the input string is valid Python:
45 compile(src_contents, "<string>", "exec") # else the bug is in hypothesmith
47 # Then format the code...
49 dst_contents = black.format_str(src_contents, mode=mode)
50 except black.InvalidInput:
51 # This is a bug - if it's valid Python code, as above, Black should be
52 # able to cope with it. See issues #970, #1012
53 # TODO: remove this try-except block when issues are resolved.
55 except TokenError as e:
56 if ( # Special-case logic for backslashes followed by newlines or end-of-input
57 e.args[0] == "EOF in multi-line statement"
58 and re.search(r"\\($|\r?\n)", src_contents) is not None
60 # This is a bug - if it's valid Python code, as above, Black should be
61 # able to cope with it. See issue #1012.
62 # TODO: remove this block when the issue is resolved.
66 # And check that we got equivalent and stable output.
67 black.assert_equivalent(src_contents, dst_contents)
68 black.assert_stable(src_contents, dst_contents, mode=mode)
70 # Future test: check that pure-python and mypyc versions of black
71 # give identical output for identical input?
74 if __name__ == "__main__":
75 # Run tests, including shrinking and reporting any known failures.
76 test_idempotent_any_syntatically_valid_python()
78 # If Atheris is available, run coverage-guided fuzzing.
79 # (if you want only bounded fuzzing, just use `pytest fuzz.py`)
87 test = test_idempotent_any_syntatically_valid_python
90 test.hypothesis.fuzz_one_input, # type: ignore[attr-defined]