fix(StaticView): demonstrate duplication of relationships

Author: yt-ms

src/structurizr/view/static_view.py

@@ -72,7 +72,7 @@ def hydrate_arguments(cls, static_view_io: StaticViewIO) -> Dict:
     @abstractmethod
     def add_all_elements(self) -> None:
         """Add all permitted elements from a model to this view."""
-        pass
+        pass  # pragma: no cover
 
     def add(
         self,

tests/unit/view/test_static_view.py

@@ -0,0 +1,76 @@
+# Copyright (c) 2020
+#
+# Licensed 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
+#
+#     https://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.
+
+
+"""Ensure the expected behaviour of StaticView."""
+
+
+import pytest
+
+from structurizr.model import Model, Person, SoftwareSystem
+from structurizr.view.static_view import StaticView
+
+
+class DerivedView(StaticView):
+    """Mock class for testing."""
+
+    def add_all_elements(self) -> None:
+        """Stub method because base is abstract."""
+        pass
+
+
+def test_add_nearest_neighbours():
+    """Test basic behaviour of add_nearest_neighbours."""
+    model = Model()
+    sys1 = model.add_software_system(name="System 1")
+    sys2 = model.add_software_system(name="System 2")
+    person = model.add_person(name="Person 1")
+    sys1.uses(sys2)
+    person.uses(sys1)
+
+    # Check neighbours from outbound relationships
+    view = DerivedView(software_system=sys1, description="")
+    view.add_nearest_neighbours(sys1, SoftwareSystem)
+    assert any((elt_view.element is sys1 for elt_view in view.element_views))
+    assert any((elt_view.element is sys2 for elt_view in view.element_views))
+    assert not any((elt_view.element is person for elt_view in view.element_views))
+    assert len(view.relationship_views) == 1
+
+    # Check neighbours from inbound relationships
+    view = DerivedView(software_system=sys1, description="")
+    view.add_nearest_neighbours(sys2, SoftwareSystem)
+    assert any((elt_view.element is sys1 for elt_view in view.element_views))
+    assert any((elt_view.element is sys2 for elt_view in view.element_views))
+    assert not any((elt_view.element is person for elt_view in view.element_views))
+    assert len(view.relationship_views) == 1
+
+
+@pytest.mark.xfail(strict=True)
+def test_add_nearest_neighbours_doesnt_dupe_relationships():
+    """Test relationships aren't duplicated if neighbours added more than once.
+
+    See https://github.com/Midnighter/structurizr-python/issues/63.
+    """
+
+    model = Model()
+    sys1 = model.add_software_system(name="System 1")
+    sys2 = model.add_software_system(name="System 2")
+    sys1.uses(sys2)
+    view = DerivedView(software_system=sys1, description="")
+    view.add_nearest_neighbours(sys1, SoftwareSystem)
+    assert len(view.relationship_views) == 1
+
+    # The next line will currently dupe the relationship
+    view.add_nearest_neighbours(sys1, Person)
+    assert len(view.relationship_views) == 1  # This fails as it's 2