251 lines
9.1 KiB
Python
251 lines
9.1 KiB
Python
""" recording warnings during test function execution. """
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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import inspect
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import re
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import sys
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import warnings
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import six
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import _pytest._code
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from _pytest.deprecated import PYTEST_WARNS_UNKNOWN_KWARGS
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from _pytest.deprecated import WARNS_EXEC
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from _pytest.fixtures import yield_fixture
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from _pytest.outcomes import fail
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@yield_fixture
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def recwarn():
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"""Return a :class:`WarningsRecorder` instance that records all warnings emitted by test functions.
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See http://docs.python.org/library/warnings.html for information
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on warning categories.
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"""
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wrec = WarningsRecorder()
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with wrec:
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warnings.simplefilter("default")
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yield wrec
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def deprecated_call(func=None, *args, **kwargs):
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"""context manager that can be used to ensure a block of code triggers a
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``DeprecationWarning`` or ``PendingDeprecationWarning``::
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>>> import warnings
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>>> def api_call_v2():
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... warnings.warn('use v3 of this api', DeprecationWarning)
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... return 200
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>>> with deprecated_call():
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... assert api_call_v2() == 200
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``deprecated_call`` can also be used by passing a function and ``*args`` and ``*kwargs``,
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in which case it will ensure calling ``func(*args, **kwargs)`` produces one of the warnings
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types above.
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"""
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__tracebackhide__ = True
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if func is not None:
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args = (func,) + args
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return warns((DeprecationWarning, PendingDeprecationWarning), *args, **kwargs)
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def warns(expected_warning, *args, **kwargs):
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r"""Assert that code raises a particular class of warning.
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Specifically, the parameter ``expected_warning`` can be a warning class or
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sequence of warning classes, and the inside the ``with`` block must issue a warning of that class or
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classes.
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This helper produces a list of :class:`warnings.WarningMessage` objects,
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one for each warning raised.
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This function can be used as a context manager, or any of the other ways
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``pytest.raises`` can be used::
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>>> with warns(RuntimeWarning):
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... warnings.warn("my warning", RuntimeWarning)
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In the context manager form you may use the keyword argument ``match`` to assert
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that the exception matches a text or regex::
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>>> with warns(UserWarning, match='must be 0 or None'):
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... warnings.warn("value must be 0 or None", UserWarning)
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>>> with warns(UserWarning, match=r'must be \d+$'):
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... warnings.warn("value must be 42", UserWarning)
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>>> with warns(UserWarning, match=r'must be \d+$'):
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... warnings.warn("this is not here", UserWarning)
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Traceback (most recent call last):
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...
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Failed: DID NOT WARN. No warnings of type ...UserWarning... was emitted...
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"""
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__tracebackhide__ = True
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if not args:
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match_expr = kwargs.pop("match", None)
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if kwargs:
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warnings.warn(
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PYTEST_WARNS_UNKNOWN_KWARGS.format(args=sorted(kwargs)), stacklevel=2
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)
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return WarningsChecker(expected_warning, match_expr=match_expr)
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elif isinstance(args[0], str):
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warnings.warn(WARNS_EXEC, stacklevel=2)
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code, = args
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assert isinstance(code, str)
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frame = sys._getframe(1)
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loc = frame.f_locals.copy()
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loc.update(kwargs)
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with WarningsChecker(expected_warning):
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code = _pytest._code.Source(code).compile()
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six.exec_(code, frame.f_globals, loc)
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else:
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func = args[0]
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with WarningsChecker(expected_warning):
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return func(*args[1:], **kwargs)
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class WarningsRecorder(warnings.catch_warnings):
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"""A context manager to record raised warnings.
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Adapted from `warnings.catch_warnings`.
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"""
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def __init__(self):
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super(WarningsRecorder, self).__init__(record=True)
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self._entered = False
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self._list = []
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@property
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def list(self):
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"""The list of recorded warnings."""
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return self._list
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def __getitem__(self, i):
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"""Get a recorded warning by index."""
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return self._list[i]
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def __iter__(self):
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"""Iterate through the recorded warnings."""
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return iter(self._list)
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def __len__(self):
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"""The number of recorded warnings."""
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return len(self._list)
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def pop(self, cls=Warning):
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"""Pop the first recorded warning, raise exception if not exists."""
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for i, w in enumerate(self._list):
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if issubclass(w.category, cls):
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return self._list.pop(i)
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__tracebackhide__ = True
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raise AssertionError("%r not found in warning list" % cls)
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def clear(self):
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"""Clear the list of recorded warnings."""
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self._list[:] = []
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def __enter__(self):
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if self._entered:
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__tracebackhide__ = True
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raise RuntimeError("Cannot enter %r twice" % self)
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self._list = super(WarningsRecorder, self).__enter__()
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warnings.simplefilter("always")
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# python3 keeps track of a "filter version", when the filters are
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# updated previously seen warnings can be re-warned. python2 has no
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# concept of this so we must reset the warnings registry manually.
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# trivial patching of `warnings.warn` seems to be enough somehow?
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if six.PY2:
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def warn(message, category=None, stacklevel=1):
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# duplicate the stdlib logic due to
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# bad handing in the c version of warnings
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if isinstance(message, Warning):
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category = message.__class__
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# Check category argument
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if category is None:
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category = UserWarning
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assert issubclass(category, Warning)
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# emulate resetting the warn registry
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f_globals = sys._getframe(stacklevel).f_globals
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if "__warningregistry__" in f_globals:
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orig = f_globals["__warningregistry__"]
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f_globals["__warningregistry__"] = None
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try:
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return self._saved_warn(message, category, stacklevel + 1)
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finally:
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f_globals["__warningregistry__"] = orig
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else:
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return self._saved_warn(message, category, stacklevel + 1)
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warnings.warn, self._saved_warn = warn, warnings.warn
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return self
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def __exit__(self, *exc_info):
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if not self._entered:
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__tracebackhide__ = True
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raise RuntimeError("Cannot exit %r without entering first" % self)
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# see above where `self._saved_warn` is assigned
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if six.PY2:
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warnings.warn = self._saved_warn
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super(WarningsRecorder, self).__exit__(*exc_info)
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# Built-in catch_warnings does not reset entered state so we do it
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# manually here for this context manager to become reusable.
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self._entered = False
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class WarningsChecker(WarningsRecorder):
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def __init__(self, expected_warning=None, match_expr=None):
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super(WarningsChecker, self).__init__()
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msg = "exceptions must be old-style classes or derived from Warning, not %s"
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if isinstance(expected_warning, tuple):
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for exc in expected_warning:
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if not inspect.isclass(exc):
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raise TypeError(msg % type(exc))
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elif inspect.isclass(expected_warning):
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expected_warning = (expected_warning,)
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elif expected_warning is not None:
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raise TypeError(msg % type(expected_warning))
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self.expected_warning = expected_warning
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self.match_expr = match_expr
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def __exit__(self, *exc_info):
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super(WarningsChecker, self).__exit__(*exc_info)
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__tracebackhide__ = True
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# only check if we're not currently handling an exception
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if all(a is None for a in exc_info):
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if self.expected_warning is not None:
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if not any(issubclass(r.category, self.expected_warning) for r in self):
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__tracebackhide__ = True
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fail(
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"DID NOT WARN. No warnings of type {} was emitted. "
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"The list of emitted warnings is: {}.".format(
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self.expected_warning, [each.message for each in self]
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)
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)
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elif self.match_expr is not None:
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for r in self:
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if issubclass(r.category, self.expected_warning):
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if re.compile(self.match_expr).search(str(r.message)):
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break
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else:
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fail(
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"DID NOT WARN. No warnings of type {} matching"
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" ('{}') was emitted. The list of emitted warnings"
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" is: {}.".format(
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self.expected_warning,
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self.match_expr,
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[each.message for each in self],
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)
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)
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