raise an error when two classes have the same ambiguous attribute

Closes linkml/linkml#2403

Signed-off-by: Vincent Kelleher <vincent.kelleher@gaia-x.eu>

Author: Vincent Kelleher

linkml_runtime/utils/schemaview.py

@@ -631,8 +631,8 @@ def get_slot(self, slot_name: SLOT_NAME, imports=True, attributes=True, strict=F
             for c in self.all_classes(imports=imports).values():
                 if slot_name in c.attributes:
                     if slot is not None:
-                        # slot name is ambiguous: return a stub slot
-                        return SlotDefinition(slot_name)
+                        raise ValueError(f'Attribute "{slot_name}" is already defined in another class, please use a '
+                                         f'slot in that case')
                     slot = copy(c.attributes[slot_name])
                     slot.from_schema = c.from_schema
                     slot.owner = c.name

tests/test_utils/input/get_slot_with_ambiguous_attributes.yaml

@@ -0,0 +1,27 @@
+id: https://examples.org/get-slot-with-attribute#
+name: get-slot-with-attribute
+
+prefixes:
+  test: https://examples.org/get-slot-with-attribute#
+
+default_prefix: test
+default_range: string
+
+classes:
+  ClassWithAttributes:
+    attributes:
+      randomAttribute:
+        description: "A random attribute for testing purposes"
+        range: integer
+        minimum_value: 0
+        maximum_value: 999
+
+  ImportantSecondClass:
+    description: "Important class to reproduce the error I got as the class loop needs to have at least a 
+              second iteration"
+    attributes:
+      randomAttribute:
+        description: "Now you see the ambiguity intensifying ?"
+        range: integer
+        minimum_value: 0
+        maximum_value: 111

tests/test_utils/test_schemaview.py

@@ -744,9 +744,6 @@ def test_ambiguous_attributes():
     a2x = SlotDefinition('a2', range='BarEnum')
     view.add_class(ClassDefinition('C2', attributes={a1x.name: a1x, a2x.name: a2x}))
 
-    assert view.get_slot(a1.name).range is None
-    assert view.get_slot(a2.name).range is None
-    assert view.get_slot(a3.name).range is not None
     assert len(view.all_slots(attributes=True)) == 3
     assert len(view.all_slots(attributes=False)) == 0
     assert len(view.all_slots()) == 3
@@ -757,6 +754,14 @@ def test_ambiguous_attributes():
     assert view.induced_slot(a2x.name, 'C2').range == a2x.range
 
 
+def test_ambiguous_attribute_through_get_slot():
+    schema_path = os.path.join(INPUT_DIR, "get_slot_with_ambiguous_attributes.yaml")
+    sv = SchemaView(schema_path)
+    with pytest.raises(ValueError) as exception:
+        sv.get_slot("randomAttribute")
+    assert exception.value == ('Attribute "randomAttribute" is already defined in another class, please use a slot in '
+                               'that case')
+
 def test_metamodel_in_schemaview():
     view = package_schemaview('linkml_runtime.linkml_model.meta')
     assert 'meta' in view.imports_closure()