Add some trivial interfaces tests.

CHANGES.rst

@@ -5,4 +5,6 @@
 0.0.1a1 (unreleased)
 ====================
 
-- Nothing yet.
+- Preliminary PyPI release. While this package is functional, it is
+  not yet documented sufficiently to be of general use. It is also not
+  expected to be fully stable.

src/nti/nikola_chameleon/interfaces.py

@@ -125,7 +125,7 @@ class IPostPage(IPost, IPageKind):
 def _build(iface, result):
     kinds = iface.getTaggedValue('__pagekinds__')
     kinds = frozenset(kinds)
-    if kinds in result and kinds:
+    if kinds in result and kinds: # pragma: no cover
         raise ValueError("Duplicate pagkeinds", kinds, iface)
 
     if kinds not in result:

src/nti/nikola_chameleon/tests/test_interfaces.py

@@ -0,0 +1,38 @@
+# -*- coding: utf-8 -*-
+"""
+Tests for interfaces.py
+
+"""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+# stdlib imports
+import unittest
+
+from nti.testing.matchers import implements
+
+from hamcrest import assert_that
+from hamcrest import has_entry
+
+# disable: accessing protected members, too many methods
+# pylint: disable=W0212,R0904
+
+
+
+class TestInterfaces(unittest.TestCase):
+
+    @property
+    def _FUT(self):
+        from nti.nikola_chameleon import interfaces
+        return interfaces
+
+    def test_post_implements(self):
+        from nikola.post import Post
+        assert_that(Post, implements(self._FUT.IPost))
+
+    def test_story_page_kind(self):
+        interfaces = self._FUT
+        assert_that(interfaces.PAGEKINDS,
+                    has_entry(frozenset(('page_page', 'story_page')),
+                              interfaces.IStoryPageKind))