adds test for dataframe handling

Author: spjuhel

climada/util/test/test_dataframe_handling.py

@@ -0,0 +1,66 @@
+"""
+This file is part of CLIMADA.
+
+Copyright (C) 2017 ETH Zurich, CLIMADA contributors listed in AUTHORS.
+
+CLIMADA is free software: you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free
+Software Foundation, version 3.
+
+CLIMADA is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with CLIMADA. If not, see <https://www.gnu.org/licenses/>.
+
+---
+
+Test coordinates module.
+"""
+
+import pandas as pd
+
+from climada.util.dataframe_handling import reorder_dataframe_columns
+
+
+def test_reorder_dataframe_columns():
+    # Setup: Create a sample DataFrame
+    df = pd.DataFrame(
+        {"A": [1, 2], "B": [3, 4], "C": [5, 6], "D": [7, 8], "E": [9, 10]}
+    )
+
+    # Test Case 1: Standard reordering with keep_remaining=True
+    # Priority: C, A (should move C and A to front, keep B, D, E in original order)
+    priority = ["C", "A", "Z"]  # 'Z' is not in df, should be ignored
+    result = reorder_dataframe_columns(df, priority, keep_remaining=True)
+
+    expected_cols = ["C", "A", "B", "D", "E"]
+    assert (
+        list(result.columns) == expected_cols
+    ), f"Expected {expected_cols}, got {list(result.columns)}"
+
+    # Test Case 2: Dropping remaining columns (keep_remaining=False)
+    # Priority: B, D (should only keep B and D)
+    priority = ["B", "D"]
+    result = reorder_dataframe_columns(df, priority, keep_remaining=False)
+
+    expected_cols = ["B", "D"]
+    assert (
+        list(result.columns) == expected_cols
+    ), f"Expected {expected_cols}, got {list(result.columns)}"
+
+    # Test Case 3: All priority columns missing
+    priority = ["X", "Y"]
+    result = reorder_dataframe_columns(df, priority, keep_remaining=True)
+
+    # Should return original order since no priority matches
+    expected_cols = ["A", "B", "C", "D", "E"]
+    assert list(result.columns) == expected_cols
+
+    # Test Case 4: Empty priority list
+    priority = []
+    result = reorder_dataframe_columns(df, priority, keep_remaining=True)
+
+    expected_cols = ["A", "B", "C", "D", "E"]
+    assert list(result.columns) == expected_cols