Adding concat tests for axis 0, 1, and 'index'

pandas/tests/frame/test_combine_concat.py

@@ -356,11 +356,26 @@ def test_concat_axis_parameter(self):
         concatted_row = pd.concat([df1, df2], axis='rows')
         assert_frame_equal(concatted_row, expected_row)
 
+        expected_index = pd.DataFrame(
+            {'A': [0.1, 0.2, 0.3, 0.4]}, index=[0, 1, 0, 1])
+        concatted_index = pd.concat([df1, df2], axis='index')
+        assert_frame_equal(concatted_index, expected_index)
+
+        expected_0 = pd.DataFrame(
+            {'A': [0.1, 0.2, 0.3, 0.4]}, index=[0, 1, 0, 1])
+        concatted_0 = pd.concat([df1, df2], axis=0)
+        assert_frame_equal(concatted_0, expected_0)
+
         expected_columns = pd.DataFrame(
             [[0.1, 0.3], [0.2, 0.4]], index=[0, 1], columns=['A', 'A'])
         concatted_columns = pd.concat([df1, df2], axis='columns')
         assert_frame_equal(concatted_columns, expected_columns)
 
+        expected_1 = pd.DataFrame(
+            [[0.1, 0.3], [0.2, 0.4]], index=[0, 1], columns=['A', 'A'])
+        concatted_1 = pd.concat([df1, df2], axis=1)
+        assert_frame_equal(concatted_1, expected_1)
+
         series1 = pd.Series([0.1, 0.2])
         series2 = pd.Series([0.3, 0.4])