test: replicate API change for Model to mocks.

Author: yt-ms

src/structurizr/model/software_system.py

@@ -100,10 +100,12 @@ def __iadd__(self, container: Container) -> "SoftwareSystem":
             container.parent = self
         elif container.parent is not self:
             raise ValueError(
-                f"Container with name {container.name} already has parent {container.parent}. Cannot add to {self}."
+                f"Container with name {container.name} already has parent "
+                f"{container.parent}. Cannot add to {self}."
             )
         self.containers.add(container)
-        self.get_model().add_container(container)
+        model = self.get_model()
+        model += container
         return self
 
     def get_container_with_name(self, name: str) -> Container:

tests/unit/model/test_software_system.py

@@ -30,12 +30,12 @@ def __init__(self):
         self.empty_system = SoftwareSystem(name="Sys")
         self.empty_system.set_model(self)
 
-    def add_container(self, container):
+    def __iadd__(self, container):
         """Simulate the model assigning IDs to new elements."""
         if not container.id:
             container.id = "id"
         container.set_model(self)
-        pass
+        return self
 
 
 @pytest.fixture(scope="function")