add a unit test

funniest/tests/test_joke.py

@@ -0,0 +1,8 @@
+from unittest import TestCase
+
+import funniest
+
+class TestJoke(TestCase):
+    def test_is_string(self):
+        s = funniest.joke()
+        self.assertTrue(isinstance(s, str))

setup.py

@@ -8,4 +8,7 @@ setup(name = "funniest",
       author_email = "flyingcircus@example.com",
       license = "MIT",
       packages = ["funniest"],
-      zip_safe = False)
+      zip_safe = False,
+      test_suite = "nose.collector",
+      tests_require = ["nose"],
+      )