refactor: postprocessing move to unit test (#18779)

tests/unit_tests/pandas_postprocessing/test_diff.py

@@ -0,0 +1,50 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+import pytest
+
+from superset.exceptions import QueryObjectValidationError
+from superset.utils.pandas_postprocessing import diff
+from tests.unit_tests.fixtures.dataframes import timeseries_df, timeseries_df2
+from tests.unit_tests.pandas_postprocessing.utils import series_to_list
+
+
+def test_diff():
+    # overwrite column
+    post_df = diff(df=timeseries_df, columns={"y": "y"})
+    assert post_df.columns.tolist() == ["label", "y"]
+    assert series_to_list(post_df["y"]) == [None, 1.0, 1.0, 1.0]
+
+    # add column
+    post_df = diff(df=timeseries_df, columns={"y": "y1"})
+    assert post_df.columns.tolist() == ["label", "y", "y1"]
+    assert series_to_list(post_df["y"]) == [1.0, 2.0, 3.0, 4.0]
+    assert series_to_list(post_df["y1"]) == [None, 1.0, 1.0, 1.0]
+
+    # look ahead
+    post_df = diff(df=timeseries_df, columns={"y": "y1"}, periods=-1)
+    assert series_to_list(post_df["y1"]) == [-1.0, -1.0, -1.0, None]
+
+    # invalid column reference
+    with pytest.raises(QueryObjectValidationError):
+        diff(
+            df=timeseries_df, columns={"abc": "abc"},
+        )
+
+    # diff by columns
+    post_df = diff(df=timeseries_df2, columns={"y": "y", "z": "z"}, axis=1)
+    assert post_df.columns.tolist() == ["label", "y", "z"]
+    assert series_to_list(post_df["z"]) == [0.0, 2.0, 8.0, 6.0]