TST: extend existing iteritems test

Author: tacaswell

pandas/tests/frame/test_api.py

@@ -160,9 +160,12 @@ def test_nonzero(self):
         assert not df.empty
 
     def test_iteritems(self):
-        df = DataFrame([[1, 2, 3], [4, 5, 6]], columns=['a', 'a', 'b'])
-        for k, v in compat.iteritems(df):
+        cols = ['a', 'a', 'b']
+        df = DataFrame([[1, 2, 3], [4, 5, 6]], columns=cols)
+        for c, (k, v) in zip(cols, compat.iteritems(df)):
+            assert c == k
             assert type(v) == Series
+            assert df[k] == v
 
     def test_items(self):
         # issue #17213