test that df.loc[:,0] returns a view

Author: margaret

pandas/tests/indexing/test_loc.py

@@ -641,10 +641,15 @@ def test_identity_slice_returns_new_object(self):
         original_df['a'] = [4, 4, 4]
         assert (sliced_df['a'] == 4).all()
 
+        # These should not return copies
+        assert original_df is original_df.loc[:, :]
+        df = DataFrame(np.random.randn(10, 4))
+        assert df[0] is df.loc[:,0]
+
+        # Same tests for Series
         original_series = Series([1, 2, 3, 4, 5, 6])
         sliced_series = original_series.loc[:]
         assert sliced_series is not original_series
 
-        # should also be a shallow copy
         original_series[:3] = [7, 8, 9]
         assert all(sliced_series[:3] == [7, 8, 9])