Assigning aggregations now protects against various invalid aggregation combinations

src/blenderbim/test/bim/feature/aggregate.feature

@@ -0,0 +1,28 @@
+@aggregate
+Feature: Aggregate
+    Covers element and spatial aggregation
+
+Scenario: Enable editing aggregate
+    Given an empty IFC project
+    And the object "IfcSite/My Site" is selected
+    When I press "bim.enable_editing_aggregate"
+    Then nothing happens
+
+Scenario: Disable editing aggregate
+    Given an empty IFC project
+    And the object "IfcSite/My Site" is selected
+    And I press "bim.enable_editing_aggregate"
+    When I press "bim.disable_editing_aggregate"
+    Then nothing happens
+
+Scenario: Assign object
+    Given an empty IFC project
+    And the object "IfcSite/My Site" is selected
+    And I press "bim.enable_editing_aggregate"
+    And the variable "relating_object" is "tool.Ifc.get().by_type('IfcSite')[0].id()"
+    And the variable "related_object" is "tool.Ifc.get().by_type('IfcBuildingStorey')[0].id()"
+    When I press "bim.assign_object(relating_object={relating_object}, related_object={related_object})"
+    Then the object "IfcSite/My Site" is in the collection "IfcSite/My Site"
+    Then the object "IfcBuildingStorey/My Storey" is in the collection "IfcBuildingStorey/My Storey"
+    Then the collection "IfcBuildingStorey/My Storey" is in the collection "IfcSite/My Site"
+

src/blenderbim/test/bim/test_feature.py

@@ -262,3 +262,8 @@ def prop_is_value(prop, value):
 @then(parsers.parse('the object "{name}" is in the collection "{collection}"'))
 def the_object_name_is_in_the_collection_collection(name, collection):
     assert collection in [c.name for c in the_object_name_exists(name).users_collection]
+
+
+@then(parsers.parse('the collection "{name1}" is in the collection "{name2}"'))
+def the_collection_name1_is_in_the_collection_name2(name1, name2):
+    assert bpy.data.collections.get(name2).children.get(name1)