add new unit tests for errors and warnings in stitchee.py

Author: danielfromearth

concatenator/stitchee.py

@@ -164,7 +164,7 @@ def _load_and_sort_datatrees(
         if sorting_variable:
             try:
                 sort_value = datatree[sorting_variable].values.flatten()[0]
-            except Exception as err:
+            except KeyError as err:
                 logger.error(
                     f"Cannot extract sorting value from '{sorting_variable}' in {filepath}: {err}"
                 )

tests/unit/test_stitchee_validations.py

@@ -0,0 +1,56 @@
+"""Tests for concatenation errors."""
+
+# pylint: disable=C0116
+
+import os
+
+import pytest
+
+from concatenator.stitchee import stitchee
+
+
+def test_no_files_to_concatenate(temp_output_dir):
+    with pytest.raises(ValueError, match="files_to_concat cannot be empty"):
+        stitchee([], output_file=os.path.join(temp_output_dir, "blank.nc"))
+
+
+def test_invalid_concat_method(temp_output_dir, toy_null_dataset):
+    with pytest.raises(ValueError, match="Unexpected concatenation method"):
+        stitchee(
+            [toy_null_dataset],
+            output_file=os.path.join(temp_output_dir, "blank.nc"),
+            concat_method="unknown-concat",
+        )
+
+
+def test_concat_dim_error_not_supplied_when_required(temp_output_dir, toy_null_dataset):
+    with pytest.raises(
+        ValueError, match="concat_dim is required when using 'xarray-concat' method"
+    ):
+        stitchee(
+            [toy_null_dataset],
+            output_file=os.path.join(temp_output_dir, "blank.nc"),
+            concat_method="xarray-concat",
+        )
+
+
+def test_concat_dim_warning_when_supplied_but_not_used(temp_output_dir, toy_null_dataset):
+    with pytest.warns(UserWarning, match="'concat_dim' was specified but will not be used"):
+        stitchee(
+            [toy_null_dataset],
+            output_file=os.path.join(temp_output_dir, "blank.nc"),
+            concat_method="xarray-combine",
+            concat_dim="some_dim",
+        )
+
+
+def test_concat_sorting_variable_not_present_in_data(
+    temp_output_dir, ds_3dims_3vars_3coords_1group_part1, ds_3dims_3vars_3coords_1group_part2
+):
+    with pytest.raises(KeyError):
+        stitchee(
+            [ds_3dims_3vars_3coords_1group_part1, ds_3dims_3vars_3coords_1group_part2],
+            output_file=os.path.join(temp_output_dir, "blank.nc"),
+            concat_dim="step",
+            sorting_variable="unknown_variable",
+        )