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Diffstat (limited to 'python/pytest/_pytest/recwarn.py')
| -rw-r--r-- | python/pytest/_pytest/recwarn.py | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/python/pytest/_pytest/recwarn.py b/python/pytest/_pytest/recwarn.py new file mode 100644 index 000000000..a89474c03 --- /dev/null +++ b/python/pytest/_pytest/recwarn.py @@ -0,0 +1,221 @@ +""" recording warnings during test function execution. """ + +import inspect + +import _pytest._code +import py +import sys +import warnings +import pytest + + +@pytest.yield_fixture +def recwarn(request): + """Return a WarningsRecorder instance that provides these methods: + + * ``pop(category=None)``: return last warning matching the category. + * ``clear()``: clear list of warnings + + See http://docs.python.org/library/warnings.html for information + on warning categories. + """ + wrec = WarningsRecorder() + with wrec: + warnings.simplefilter('default') + yield wrec + + +def pytest_namespace(): + return {'deprecated_call': deprecated_call, + 'warns': warns} + + +def deprecated_call(func=None, *args, **kwargs): + """ assert that calling ``func(*args, **kwargs)`` triggers a + ``DeprecationWarning`` or ``PendingDeprecationWarning``. + + This function can be used as a context manager:: + + >>> with deprecated_call(): + ... myobject.deprecated_method() + + Note: we cannot use WarningsRecorder here because it is still subject + to the mechanism that prevents warnings of the same type from being + triggered twice for the same module. See #1190. + """ + if not func: + return WarningsChecker(expected_warning=DeprecationWarning) + + categories = [] + + def warn_explicit(message, category, *args, **kwargs): + categories.append(category) + old_warn_explicit(message, category, *args, **kwargs) + + def warn(message, category=None, *args, **kwargs): + if isinstance(message, Warning): + categories.append(message.__class__) + else: + categories.append(category) + old_warn(message, category, *args, **kwargs) + + old_warn = warnings.warn + old_warn_explicit = warnings.warn_explicit + warnings.warn_explicit = warn_explicit + warnings.warn = warn + try: + ret = func(*args, **kwargs) + finally: + warnings.warn_explicit = old_warn_explicit + warnings.warn = old_warn + deprecation_categories = (DeprecationWarning, PendingDeprecationWarning) + if not any(issubclass(c, deprecation_categories) for c in categories): + __tracebackhide__ = True + raise AssertionError("%r did not produce DeprecationWarning" % (func,)) + return ret + + +def warns(expected_warning, *args, **kwargs): + """Assert that code raises a particular class of warning. + + Specifically, the input @expected_warning can be a warning class or + tuple of warning classes, and the code must return that warning + (if a single class) or one of those warnings (if a tuple). + + This helper produces a list of ``warnings.WarningMessage`` objects, + one for each warning raised. + + This function can be used as a context manager, or any of the other ways + ``pytest.raises`` can be used:: + + >>> with warns(RuntimeWarning): + ... warnings.warn("my warning", RuntimeWarning) + """ + wcheck = WarningsChecker(expected_warning) + if not args: + return wcheck + elif isinstance(args[0], str): + code, = args + assert isinstance(code, str) + frame = sys._getframe(1) + loc = frame.f_locals.copy() + loc.update(kwargs) + + with wcheck: + code = _pytest._code.Source(code).compile() + py.builtin.exec_(code, frame.f_globals, loc) + else: + func = args[0] + with wcheck: + return func(*args[1:], **kwargs) + + +class RecordedWarning(object): + def __init__(self, message, category, filename, lineno, file, line): + self.message = message + self.category = category + self.filename = filename + self.lineno = lineno + self.file = file + self.line = line + + +class WarningsRecorder(object): + """A context manager to record raised warnings. + + Adapted from `warnings.catch_warnings`. + """ + + def __init__(self, module=None): + self._module = sys.modules['warnings'] if module is None else module + self._entered = False + self._list = [] + + @property + def list(self): + """The list of recorded warnings.""" + return self._list + + def __getitem__(self, i): + """Get a recorded warning by index.""" + return self._list[i] + + def __iter__(self): + """Iterate through the recorded warnings.""" + return iter(self._list) + + def __len__(self): + """The number of recorded warnings.""" + return len(self._list) + + def pop(self, cls=Warning): + """Pop the first recorded warning, raise exception if not exists.""" + for i, w in enumerate(self._list): + if issubclass(w.category, cls): + return self._list.pop(i) + __tracebackhide__ = True + raise AssertionError("%r not found in warning list" % cls) + + def clear(self): + """Clear the list of recorded warnings.""" + self._list[:] = [] + + def __enter__(self): + if self._entered: + __tracebackhide__ = True + raise RuntimeError("Cannot enter %r twice" % self) + self._entered = True + self._filters = self._module.filters + self._module.filters = self._filters[:] + self._showwarning = self._module.showwarning + + def showwarning(message, category, filename, lineno, + file=None, line=None): + self._list.append(RecordedWarning( + message, category, filename, lineno, file, line)) + + # still perform old showwarning functionality + self._showwarning( + message, category, filename, lineno, file=file, line=line) + + self._module.showwarning = showwarning + + # allow the same warning to be raised more than once + + self._module.simplefilter('always') + return self + + def __exit__(self, *exc_info): + if not self._entered: + __tracebackhide__ = True + raise RuntimeError("Cannot exit %r without entering first" % self) + self._module.filters = self._filters + self._module.showwarning = self._showwarning + + +class WarningsChecker(WarningsRecorder): + def __init__(self, expected_warning=None, module=None): + super(WarningsChecker, self).__init__(module=module) + + msg = ("exceptions must be old-style classes or " + "derived from Warning, not %s") + if isinstance(expected_warning, tuple): + for exc in expected_warning: + if not inspect.isclass(exc): + raise TypeError(msg % type(exc)) + elif inspect.isclass(expected_warning): + expected_warning = (expected_warning,) + elif expected_warning is not None: + raise TypeError(msg % type(expected_warning)) + + self.expected_warning = expected_warning + + def __exit__(self, *exc_info): + super(WarningsChecker, self).__exit__(*exc_info) + + # only check if we're not currently handling an exception + if all(a is None for a in exc_info): + if self.expected_warning is not None: + if not any(r.category in self.expected_warning for r in self): + __tracebackhide__ = True + pytest.fail("DID NOT WARN") |