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from typing import Optional, Type, TypeVar, Union, overload
from hamcrest.core.base_matcher import BaseMatcher
from hamcrest.core.description import Description
from hamcrest.core.helpers.wrap_matcher import is_matchable_type, wrap_matcher
from hamcrest.core.matcher import Matcher
from .isinstanceof import instance_of
__author__ = "Jon Reid"
__copyright__ = "Copyright 2011 hamcrest.org"
__license__ = "BSD, see License.txt"
T = TypeVar("T")
class Is(BaseMatcher[T]):
def __init__(self, matcher: Matcher[T]) -> None:
self.matcher = matcher
def matches(self, item: T, mismatch_description: Optional[Description] = None) -> bool:
return self.matcher.matches(item, mismatch_description)
def describe_mismatch(self, item: T, mismatch_description: Description) -> None:
return self.matcher.describe_mismatch(item, mismatch_description)
def describe_to(self, description: Description):
description.append_description_of(self.matcher)
@overload
def _wrap_value_or_type(x: Type) -> Matcher[object]:
...
@overload
def _wrap_value_or_type(x: T) -> Matcher[T]:
...
def _wrap_value_or_type(x):
if is_matchable_type(x):
return instance_of(x)
else:
return wrap_matcher(x)
@overload
def is_(x: Type) -> Matcher[object]:
...
@overload
def is_(x: Union[Matcher[T], T]) -> Matcher[T]:
...
def is_(x):
"""Decorates another matcher, or provides shortcuts to the frequently used
``is(equal_to(x))`` and ``is(instance_of(x))``.
:param x: The matcher to satisfy, or a type for
:py:func:`~hamcrest.core.core.isinstanceof.instance_of` matching, or an
expected value for :py:func:`~hamcrest.core.core.isequal.equal_to`
matching.
This matcher compares the evaluated object to the given matcher.
.. note::
PyHamcrest's ``is_`` matcher is unrelated to Python's ``is`` operator.
The matcher for object identity is
:py:func:`~hamcrest.core.core.issame.same_instance`.
If the ``x`` argument is a matcher, its behavior is retained, but the test
may be more expressive. For example::
assert_that(value, less_than(5))
assert_that(value, is_(less_than(5)))
If the ``x`` argument is a type, it is wrapped in an
:py:func:`~hamcrest.core.core.isinstanceof.instance_of` matcher. This makes
the following statements equivalent::
assert_that(cheese, instance_of(Cheddar))
assert_that(cheese, is_(instance_of(Cheddar)))
assert_that(cheese, is_(Cheddar))
Otherwise, if the ``x`` argument is not a matcher, it is wrapped in an
:py:func:`~hamcrest.core.core.isequal.equal_to` matcher. This makes the
following statements equivalent::
assert_that(cheese, equal_to(smelly))
assert_that(cheese, is_(equal_to(smelly)))
assert_that(cheese, is_(smelly))
Choose the style that makes your expression most readable. This will vary
depending on context.
"""
return Is(_wrap_value_or_type(x))
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