writing docstrings to explain the behaviour of the test functions

tests/test_unit/test_validation.py

@@ -78,13 +78,17 @@ def test_validate_mesh_structure_pairs_no_obj(atlas):
     when there is at least one structure in the atlas that doesn't have
     a corresponding obj file.
 
-    True for: allen_mouse_100um (structure 545 doesn't have an obj file)
-    False for: admba_3d_e11_5_mouse_16um (it has all pairs)
+    Expected behaviour:
+    True for "allen_mouse_10um" (structure 545 doesn't have an obj file): fails
+    the validation function, raises an error --> no output from this test function
+
+    False for "admba_3d_e11_5_mouse_16um" (it has all pairs): no error is
+    raised by the validation function --> this test function catches it
 
     """
     with pytest.raises(
         AssertionError,
-        match="Structures with ID \[.*\] are in the atlas, but don't have a corresponding mesh file",
+        match=r"Structures with ID \[.*?\] are in the atlas, but don't have a corresponding mesh file;",
     ):
         validate_mesh_structure_pairs(atlas)
 
@@ -93,9 +97,13 @@ def test_validate_mesh_structure_pairs_not_in_atlas(atlas):
     """
     Tests if validate_mesh_structure_pairs function raises an error,
     when there is at least one orphan obj file (doesn't have a corresponding structure in the atlas)
+
+    Expected behaviour:
+    Currently no atlas fails the validation function this way so the [] is always empty
+    --> this test function should always raise an error
     """
     with pytest.raises(
         AssertionError,
-        match="Structures with IDs \[.*\] have a mesh file, but are not accessible through the atlas",
+        match=r"Structures with IDs \[.*?\] have a mesh file, but are not accessible through the atlas.",
     ):
         validate_mesh_structure_pairs(atlas)