Add interface again.

testtools/tests/matchers/helpers.py

@@ -0,0 +1,42 @@
+# Copyright (c) 2008-2012 testtools developers. See LICENSE for details.
+
+from testtools.tests.helpers import FullStackRunTest
+
+
+class TestMatchersInterface(object):
+
+    run_tests_with = FullStackRunTest
+
+    def test_matches_match(self):
+        matcher = self.matches_matcher
+        matches = self.matches_matches
+        mismatches = self.matches_mismatches
+        for candidate in matches:
+            self.assertEqual(None, matcher.match(candidate))
+        for candidate in mismatches:
+            mismatch = matcher.match(candidate)
+            self.assertNotEqual(None, mismatch)
+            self.assertNotEqual(None, getattr(mismatch, 'describe', None))
+
+    def test__str__(self):
+        # [(expected, object to __str__)].
+        from testtools.matchers._doctest import DocTestMatches
+        examples = self.str_examples
+        for expected, matcher in examples:
+            self.assertThat(matcher, DocTestMatches(expected))
+
+    def test_describe_difference(self):
+        # [(expected, matchee, matcher), ...]
+        examples = self.describe_examples
+        for difference, matchee, matcher in examples:
+            mismatch = matcher.match(matchee)
+            self.assertEqual(difference, mismatch.describe())
+
+    def test_mismatch_details(self):
+        # The mismatch object must provide get_details, which must return a
+        # dictionary mapping names to Content objects.
+        examples = self.describe_examples
+        for difference, matchee, matcher in examples:
+            mismatch = matcher.match(matchee)
+            details = mismatch.get_details()
+            self.assertEqual(dict(details), details)