Add '.vim/bundle/black/' from commit '2f3fa1f6d0cbc2a3f31c7440c422da173b068e7b'

[etc/vim.git] / .vim / bundle / black / fuzz.py

diff --git a/.vim/bundle/black/fuzz.py b/.vim/bundle/black/fuzz.py
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+"""Property-based tests for Black.
+
+By Zac Hatfield-Dodds, based on my Hypothesmith tool for source code
+generation.  You can run this file with `python`, `pytest`, or (soon)
+a coverage-guided fuzzer I'm working on.
+"""
+
+import re
+
+import hypothesmith
+from hypothesis import HealthCheck, given, settings, strategies as st
+
+import black
+from blib2to3.pgen2.tokenize import TokenError
+
+
+# This test uses the Hypothesis and Hypothesmith libraries to generate random
+# syntatically-valid Python source code and run Black in odd modes.
+@settings(
+    max_examples=1000,  # roughly 1k tests/minute, or half that under coverage
+    derandomize=True,  # deterministic mode to avoid CI flakiness
+    deadline=None,  # ignore Hypothesis' health checks; we already know that
+    suppress_health_check=HealthCheck.all(),  # this is slow and filter-heavy.
+)
+@given(
+    # Note that while Hypothesmith might generate code unlike that written by
+    # humans, it's a general test that should pass for any *valid* source code.
+    # (so e.g. running it against code scraped of the internet might also help)
+    src_contents=hypothesmith.from_grammar() | hypothesmith.from_node(),
+    # Using randomly-varied modes helps us to exercise less common code paths.
+    mode=st.builds(
+        black.FileMode,
+        line_length=st.just(88) | st.integers(0, 200),
+        string_normalization=st.booleans(),
+        is_pyi=st.booleans(),
+    ),
+)
+def test_idempotent_any_syntatically_valid_python(
+    src_contents: str, mode: black.FileMode
+) -> None:
+    # Before starting, let's confirm that the input string is valid Python:
+    compile(src_contents, "<string>", "exec")  # else the bug is in hypothesmith
+
+    # Then format the code...
+    try:
+        dst_contents = black.format_str(src_contents, mode=mode)
+    except black.InvalidInput:
+        # This is a bug - if it's valid Python code, as above, Black should be
+        # able to cope with it.  See issues #970, #1012, #1358, and #1557.
+        # TODO: remove this try-except block when issues are resolved.
+        return
+    except TokenError as e:
+        if (  # Special-case logic for backslashes followed by newlines or end-of-input
+            e.args[0] == "EOF in multi-line statement"
+            and re.search(r"\\($|\r?\n)", src_contents) is not None
+        ):
+            # This is a bug - if it's valid Python code, as above, Black should be
+            # able to cope with it.  See issue #1012.
+            # TODO: remove this block when the issue is resolved.
+            return
+        raise
+
+    # And check that we got equivalent and stable output.
+    black.assert_equivalent(src_contents, dst_contents)
+    black.assert_stable(src_contents, dst_contents, mode=mode)
+
+    # Future test: check that pure-python and mypyc versions of black
+    # give identical output for identical input?
+
+
+if __name__ == "__main__":
+    # Run tests, including shrinking and reporting any known failures.
+    test_idempotent_any_syntatically_valid_python()
+
+    # If Atheris is available, run coverage-guided fuzzing.
+    # (if you want only bounded fuzzing, just use `pytest fuzz.py`)
+    try:
+        import sys
+        import atheris
+    except ImportError:
+        pass
+    else:
+        test = test_idempotent_any_syntatically_valid_python
+        atheris.Setup(sys.argv, test.hypothesis.fuzz_one_input)
+        atheris.Fuzz()