# Copyright (c) 2008-2017 testtools developers. See LICENSE for details.

"""Assertion helpers."""

from typing import TypeVar

from testtools.matchers import (

Annotate,

Matcher,

MismatchError,

)

T = TypeVar("T")

def assert_that(

matchee: T, matcher: Matcher[T], message: str = "", verbose: bool = False

) -> None:

"""Assert that matchee is matched by matcher.

This should only be used when you need to use a function based

matcher, assertThat in Testtools.Testcase is preferred and has more

features

:param matchee: An object to match with matcher.

:param matcher: An object meeting the testtools.Matcher protocol.

:raises MismatchError: When matcher does not match thing.

"""

matcher = Annotate.if_message(message, matcher)

mismatch = matcher.match(matchee)

if not mismatch:

return

raise MismatchError(matchee, matcher, mismatch, verbose)