TST: Add test for nested JSON normalization (pandas-dev#29225)

Author: gfyoung

pandas/tests/io/json/test_normalize.py

@@ -457,6 +457,14 @@ def test_max_level_with_records_path(self, max_level, expected):
         expected_df = DataFrame(data=expected, columns=result.columns.values)
         tm.assert_equal(expected_df, result)
 
+    def test_nested_flattening_consistent(self):
+        # see gh-21537
+        df1 = json_normalize([{"A": {"B": 1}}])
+        df2 = json_normalize({"dummy": [{"A": {"B": 1}}]}, "dummy")
+
+        # They should be the same.
+        tm.assert_frame_equal(df1, df2)
+
 
 class TestNestedToRecord:
     def test_flat_stays_flat(self):