done

lib/python3.11/site-packages/pandas/tests/frame/methods/test_swaplevel.py

@@ -0,0 +1,36 @@
+import pytest
+
+from pandas import DataFrame
+import pandas._testing as tm
+
+
+class TestSwaplevel:
+    def test_swaplevel(self, multiindex_dataframe_random_data):
+        frame = multiindex_dataframe_random_data
+
+        swapped = frame["A"].swaplevel()
+        swapped2 = frame["A"].swaplevel(0)
+        swapped3 = frame["A"].swaplevel(0, 1)
+        swapped4 = frame["A"].swaplevel("first", "second")
+        assert not swapped.index.equals(frame.index)
+        tm.assert_series_equal(swapped, swapped2)
+        tm.assert_series_equal(swapped, swapped3)
+        tm.assert_series_equal(swapped, swapped4)
+
+        back = swapped.swaplevel()
+        back2 = swapped.swaplevel(0)
+        back3 = swapped.swaplevel(0, 1)
+        back4 = swapped.swaplevel("second", "first")
+        assert back.index.equals(frame.index)
+        tm.assert_series_equal(back, back2)
+        tm.assert_series_equal(back, back3)
+        tm.assert_series_equal(back, back4)
+
+        ft = frame.T
+        swapped = ft.swaplevel("first", "second", axis=1)
+        exp = frame.swaplevel("first", "second").T
+        tm.assert_frame_equal(swapped, exp)
+
+        msg = "Can only swap levels on a hierarchical axis."
+        with pytest.raises(TypeError, match=msg):
+            DataFrame(range(3)).swaplevel()