Made sure commaAndify raises TypeError when it's given lists of non-strings.

src/utils.py

@@ -256,9 +256,10 @@ def commaAndify(seq, And='and'):
     if len(L) == 0:
         return ''
     elif len(L) == 1:
-        return L[0]
+        return ''.join(L) # We need this because it raises TypeError.
     elif len(L) == 2:
-        return '%s %s %s' % (L[0], And, L[1])
+        L.insert(1, And)
+        return ' '.join(L)
     else:
         L[-1] = '%s %s' % (And, L[-1])
         return ', '.join(L)

test/test_utils.py

@@ -180,6 +180,12 @@ class UtilsTest(unittest.TestCase):
         self.assertEqual(L, original)
         self.failUnless(utils.commaAndify(sets.Set(L)))
 
+    def testCommaAndifyRaisesTypeError(self):
+        L = [(2,)]
+        self.assertRaises(TypeError, utils.commaAndify, L)
+        L.append((3,))
+        self.assertRaises(TypeError, utils.commaAndify, L)
+
     def testUnCommaThe(self):
         self.assertEqual(utils.unCommaThe('foo bar'), 'foo bar')
         self.assertEqual(utils.unCommaThe('foo bar, the'), 'the foo bar')