add some tests for our matchers

src/_secureaccesstokenauthorizer/tests/test_matchers.py

+# Copyright 2019 PrivateStorage.io, LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Tests for ``_secureaccesstokenauthorizer.tests.matchers``.
+"""
+
+from zope.interface import (
+    Interface,
+    implementer,
+)
+
+from testtools import (
+    TestCase,
+)
+from testtools.matchers import (
+    Not,
+    Is,
+)
+
+from .matchers import (
+    Provides,
+    returns,
+)
+
+
+class IX(Interface):
+    pass
+
+
+class IY(Interface):
+    pass
+
+
+@implementer(IX)
+class X(object):
+    pass
+
+
+class Z(object):
+    pass
+
+
+class ProvidesTests(TestCase):
+    """
+    Tests for ``Provides``.
+    """
+    def test_match(self):
+        """
+        ``Provides.match`` returns ``None`` when the given object provides any of
+        the configured interfaces.
+        """
+        self.assertThat(
+            Provides([IX, IY]).match(X()),
+            Is(None),
+        )
+
+    def test_mismatch(self):
+        """
+        ``Provides.match`` does not return ``None`` when the given object provides
+        none of the configured interfaces.
+        """
+        self.assertThat(
+            Provides([IX, IY]).match(Z()),
+            Not(Is(None)),
+        )
+
+
+class ReturnsTests(TestCase):
+    """
+    Tests for ``returns``.
+    """
+    def test_match(self):
+        """
+        ``returns(m)`` returns a matcher that matches when the given object
+        returns a value matched by ``m``.
+        """
+        result = object()
+        self.assertThat(
+            returns(Is(result)).match(lambda: result),
+            Is(None),
+        )
+
+    def test_mismatch(self):
+        """
+        ``returns(m)`` returns a matcher that does not match when the given object
+        returns a value not matched by ``m``.
+        """
+        result = object()
+        other = object()
+        self.assertThat(
+            returns(Is(result)).match(lambda: other),
+            Not(Is(None)),
+        )