Source code for _pytest.recwarn

""" recording warnings during test function execution. """
import re
import warnings
from types import TracebackType
from typing import Any
from typing import Callable
from typing import Iterator
from typing import List
from typing import Optional
from typing import Pattern
from typing import Tuple
from typing import Union

from _pytest.compat import overload
from _pytest.compat import TYPE_CHECKING
from _pytest.fixtures import yield_fixture
from _pytest.outcomes import fail

    from typing import Type

[docs]@yield_fixture def recwarn(): """Return a :class:`WarningsRecorder` instance that records all warnings emitted by test functions. See for information on warning categories. """ wrec = WarningsRecorder() with wrec: warnings.simplefilter("default") yield wrec
[docs]def deprecated_call(func=None, *args, **kwargs): """context manager that can be used to ensure a block of code triggers a ``DeprecationWarning`` or ``PendingDeprecationWarning``:: >>> import warnings >>> def api_call_v2(): ... warnings.warn('use v3 of this api', DeprecationWarning) ... return 200 >>> with deprecated_call(): ... assert api_call_v2() == 200 ``deprecated_call`` can also be used by passing a function and ``*args`` and ``*kwargs``, in which case it will ensure calling ``func(*args, **kwargs)`` produces one of the warnings types above. """ __tracebackhide__ = True if func is not None: args = (func,) + args return warns((DeprecationWarning, PendingDeprecationWarning), *args, **kwargs)
@overload def warns( expected_warning: Optional[Union["Type[Warning]", Tuple["Type[Warning]", ...]]], *, match: "Optional[Union[str, Pattern]]" = ... ) -> "WarningsChecker": raise NotImplementedError() @overload # noqa: F811 def warns( # noqa: F811 expected_warning: Optional[Union["Type[Warning]", Tuple["Type[Warning]", ...]]], func: Callable, *args: Any, match: Optional[Union[str, "Pattern"]] = ..., **kwargs: Any ) -> Union[Any]: raise NotImplementedError()
[docs]def warns( # noqa: F811 expected_warning: Optional[Union["Type[Warning]", Tuple["Type[Warning]", ...]]], *args: Any, match: Optional[Union[str, "Pattern"]] = None, **kwargs: Any ) -> Union["WarningsChecker", Any]: r"""Assert that code raises a particular class of warning. Specifically, the parameter ``expected_warning`` can be a warning class or sequence of warning classes, and the inside the ``with`` block must issue a warning of that class or classes. This helper produces a list of :class:`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) In the context manager form you may use the keyword argument ``match`` to assert that the exception matches a text or regex:: >>> with warns(UserWarning, match='must be 0 or None'): ... warnings.warn("value must be 0 or None", UserWarning) >>> with warns(UserWarning, match=r'must be \d+$'): ... warnings.warn("value must be 42", UserWarning) >>> with warns(UserWarning, match=r'must be \d+$'): ... warnings.warn("this is not here", UserWarning) Traceback (most recent call last): ... Failed: DID NOT WARN. No warnings of type ...UserWarning... was emitted... """ __tracebackhide__ = True if not args: if kwargs: msg = "Unexpected keyword arguments passed to pytest.warns: " msg += ", ".join(sorted(kwargs)) msg += "\nUse context-manager form instead?" raise TypeError(msg) return WarningsChecker(expected_warning, match_expr=match) else: func = args[0] if not callable(func): raise TypeError( "{!r} object (type: {}) must be callable".format(func, type(func)) ) with WarningsChecker(expected_warning): return func(*args[1:], **kwargs)
[docs]class WarningsRecorder(warnings.catch_warnings): """A context manager to record raised warnings. Adapted from `warnings.catch_warnings`. """ def __init__(self): super().__init__(record=True) self._entered = False self._list = [] # type: List[warnings._Record] @property def list(self) -> List["warnings._Record"]: """The list of recorded warnings.""" return self._list def __getitem__(self, i: int) -> "warnings._Record": """Get a recorded warning by index.""" return self._list[i] def __iter__(self) -> Iterator["warnings._Record"]: """Iterate through the recorded warnings.""" return iter(self._list) def __len__(self) -> int: """The number of recorded warnings.""" return len(self._list)
[docs] def pop(self, cls: "Type[Warning]" = Warning) -> "warnings._Record": """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)
[docs] def clear(self) -> None: """Clear the list of recorded warnings.""" self._list[:] = []
# Type ignored because it doesn't exactly warnings.catch_warnings.__enter__ # -- it returns a List but we only emulate one. def __enter__(self) -> "WarningsRecorder": # type: ignore if self._entered: __tracebackhide__ = True raise RuntimeError("Cannot enter %r twice" % self) _list = super().__enter__() # record=True means it's None. assert _list is not None self._list = _list warnings.simplefilter("always") return self def __exit__( self, exc_type: Optional["Type[BaseException]"], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType], ) -> None: if not self._entered: __tracebackhide__ = True raise RuntimeError("Cannot exit %r without entering first" % self) super().__exit__(exc_type, exc_val, exc_tb) # Built-in catch_warnings does not reset entered state so we do it # manually here for this context manager to become reusable. self._entered = False
class WarningsChecker(WarningsRecorder): def __init__( self, expected_warning: Optional[ Union["Type[Warning]", Tuple["Type[Warning]", ...]] ] = None, match_expr: Optional[Union[str, "Pattern"]] = None, ) -> None: super().__init__() msg = "exceptions must be derived from Warning, not %s" if expected_warning is None: expected_warning_tup = None elif isinstance(expected_warning, tuple): for exc in expected_warning: if not issubclass(exc, Warning): raise TypeError(msg % type(exc)) expected_warning_tup = expected_warning elif issubclass(expected_warning, Warning): expected_warning_tup = (expected_warning,) else: raise TypeError(msg % type(expected_warning)) self.expected_warning = expected_warning_tup self.match_expr = match_expr def __exit__( self, exc_type: Optional["Type[BaseException]"], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType], ) -> None: super().__exit__(exc_type, exc_val, exc_tb) __tracebackhide__ = True # only check if we're not currently handling an exception if exc_type is None and exc_val is None and exc_tb is None: if self.expected_warning is not None: if not any(issubclass(r.category, self.expected_warning) for r in self): __tracebackhide__ = True fail( "DID NOT WARN. No warnings of type {} was emitted. " "The list of emitted warnings is: {}.".format( self.expected_warning, [each.message for each in self] ) ) elif self.match_expr is not None: for r in self: if issubclass(r.category, self.expected_warning): if re.compile(self.match_expr).search(str(r.message)): break else: fail( "DID NOT WARN. No warnings of type {} matching" " ('{}') was emitted. The list of emitted warnings" " is: {}.".format( self.expected_warning, self.match_expr, [each.message for each in self], ) )