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third_party/pybind11/tests/conftest.py

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+"""pytest configuration
+
+Extends output capture as needed by pybind11: ignore constructors, optional unordered lines.
+Adds docstring and exceptions message sanitizers.
+"""
+
+import contextlib
+import difflib
+import gc
+import re
+import textwrap
+
+import pytest
+
+# Early diagnostic for failed imports
+import pybind11_tests  # noqa: F401
+
+_long_marker = re.compile(r"([0-9])L")
+_hexadecimal = re.compile(r"0x[0-9a-fA-F]+")
+
+# Avoid collecting Python3 only files
+collect_ignore = []
+
+
+def _strip_and_dedent(s):
+    """For triple-quote strings"""
+    return textwrap.dedent(s.lstrip("\n").rstrip())
+
+
+def _split_and_sort(s):
+    """For output which does not require specific line order"""
+    return sorted(_strip_and_dedent(s).splitlines())
+
+
+def _make_explanation(a, b):
+    """Explanation for a failed assert -- the a and b arguments are List[str]"""
+    return ["--- actual / +++ expected"] + [
+        line.strip("\n") for line in difflib.ndiff(a, b)
+    ]
+
+
+class Output:
+    """Basic output post-processing and comparison"""
+
+    def __init__(self, string):
+        self.string = string
+        self.explanation = []
+
+    def __str__(self):
+        return self.string
+
+    def __eq__(self, other):
+        # Ignore constructor/destructor output which is prefixed with "###"
+        a = [
+            line for line in self.string.strip().splitlines()
+            if not line.startswith("###")
+        ]
+        b = _strip_and_dedent(other).splitlines()
+        if a == b:
+            return True
+        else:
+            self.explanation = _make_explanation(a, b)
+            return False
+
+
+class Unordered(Output):
+    """Custom comparison for output without strict line ordering"""
+
+    def __eq__(self, other):
+        a = _split_and_sort(self.string)
+        b = _split_and_sort(other)
+        if a == b:
+            return True
+        else:
+            self.explanation = _make_explanation(a, b)
+            return False
+
+
+class Capture:
+    def __init__(self, capfd):
+        self.capfd = capfd
+        self.out = ""
+        self.err = ""
+
+    def __enter__(self):
+        self.capfd.readouterr()
+        return self
+
+    def __exit__(self, *args):
+        self.out, self.err = self.capfd.readouterr()
+
+    def __eq__(self, other):
+        a = Output(self.out)
+        b = other
+        if a == b:
+            return True
+        else:
+            self.explanation = a.explanation
+            return False
+
+    def __str__(self):
+        return self.out
+
+    def __contains__(self, item):
+        return item in self.out
+
+    @property
+    def unordered(self):
+        return Unordered(self.out)
+
+    @property
+    def stderr(self):
+        return Output(self.err)
+
+
+@pytest.fixture
+def capture(capsys):
+    """Extended `capsys` with context manager and custom equality operators"""
+    return Capture(capsys)
+
+
+class SanitizedString:
+    def __init__(self, sanitizer):
+        self.sanitizer = sanitizer
+        self.string = ""
+        self.explanation = []
+
+    def __call__(self, thing):
+        self.string = self.sanitizer(thing)
+        return self
+
+    def __eq__(self, other):
+        a = self.string
+        b = _strip_and_dedent(other)
+        if a == b:
+            return True
+        else:
+            self.explanation = _make_explanation(a.splitlines(),
+                                                 b.splitlines())
+            return False
+
+
+def _sanitize_general(s):
+    s = s.strip()
+    s = s.replace("pybind11_tests.", "m.")
+    s = _long_marker.sub(r"\1", s)
+    return s
+
+
+def _sanitize_docstring(thing):
+    s = thing.__doc__
+    s = _sanitize_general(s)
+    return s
+
+
+@pytest.fixture
+def doc():
+    """Sanitize docstrings and add custom failure explanation"""
+    return SanitizedString(_sanitize_docstring)
+
+
+def _sanitize_message(thing):
+    s = str(thing)
+    s = _sanitize_general(s)
+    s = _hexadecimal.sub("0", s)
+    return s
+
+
+@pytest.fixture
+def msg():
+    """Sanitize messages and add custom failure explanation"""
+    return SanitizedString(_sanitize_message)
+
+
+# noinspection PyUnusedLocal
+def pytest_assertrepr_compare(op, left, right):
+    """Hook to insert custom failure explanation"""
+    if hasattr(left, "explanation"):
+        return left.explanation
+
+
+@contextlib.contextmanager
+def suppress(exception):
+    """Suppress the desired exception"""
+    try:
+        yield
+    except exception:
+        pass
+
+
+def gc_collect():
+    """Run the garbage collector twice (needed when running
+    reference counting tests with PyPy)"""
+    gc.collect()
+    gc.collect()
+
+
+def pytest_configure():
+    pytest.suppress = suppress
+    pytest.gc_collect = gc_collect