AR-6 bugfix: ensure there is only one aggregate root after merging (#81)

Author: stefan-ka

org.contextmapper.dsl.tests/integ-test-files/refactorings/merge-aggregates-test-6-input.cml

@@ -0,0 +1,13 @@
+BoundedContext AnotherContext {
+	Aggregate agg1 {
+		Entity MyEntity {
+			aggregateRoot
+		}
+	}
+	
+	Aggregate agg2 {
+		Entity MyOtherEntity {
+			aggregateRoot
+		}
+	}
+}

org.contextmapper.dsl.tests/src/org/contextmapper/dsl/tests/refactoring/MergeAggregatesTest.java

@@ -18,6 +18,7 @@
 import org.contextmapper.dsl.contextMappingDSL.UpstreamDownstreamRelationship;
 import org.contextmapper.dsl.refactoring.MergeAggregatesRefactoring;
 import org.contextmapper.dsl.refactoring.exception.RefactoringInputException;
+import org.contextmapper.tactic.dsl.tacticdsl.DomainObject;
 import org.eclipse.emf.ecore.resource.Resource;
 import org.eclipse.xtext.xbase.lib.IteratorExtensions;
 import org.junit.jupiter.api.Assertions;
@@ -214,7 +215,7 @@ void canTakeAttributesFromFirstAggregateByDefault() throws IOException {
 		assertEquals("agg1", aggregate.getName());
 		assertEquals("TeamA", aggregate.getOwner().getName());
 	}
-	
+
 	@Test
 	void canTakeAttributesFromSecondAggregate() throws IOException {
 		// given
@@ -238,4 +239,26 @@ void canTakeAttributesFromSecondAggregate() throws IOException {
 		assertEquals("TeamB", aggregate.getOwner().getName());
 	}
 
+	@Test
+	void canHandleAggregateRoots() throws IOException {
+		// given
+		String inputModelName = "merge-aggregates-test-6-input.cml";
+		Resource input = getResourceCopyOfTestCML(inputModelName);
+		MergeAggregatesRefactoring refactoring = new MergeAggregatesRefactoring("agg1", "agg2", true);
+
+		// when
+		refactoring.doRefactor(input);
+
+		// then
+		List<ContextMappingModel> contextMappingModels = IteratorExtensions
+				.<ContextMappingModel>toList(Iterators.<ContextMappingModel>filter(reloadResource(input).getAllContents(), ContextMappingModel.class));
+		assertEquals(1, contextMappingModels.get(0).getBoundedContexts().size());
+		BoundedContext bc = contextMappingModels.get(0).getBoundedContexts().get(0);
+		assertEquals(1, bc.getAggregates().size());
+		Aggregate aggregate = bc.getAggregates().get(0);
+		List<DomainObject> aggregateRoots = aggregate.getDomainObjects().stream().filter(o -> o instanceof DomainObject).map(o -> (DomainObject) o).filter(o -> o.isAggregateRoot())
+				.collect(Collectors.toList());
+		assertEquals(1, aggregateRoots.size());
+	}
+
 }

org.contextmapper.dsl/src/org/contextmapper/dsl/refactoring/MergeAggregatesRefactoring.java

@@ -28,6 +28,7 @@
 import org.contextmapper.dsl.contextMappingDSL.UpstreamDownstreamRelationship;
 import org.contextmapper.dsl.refactoring.exception.RefactoringInputException;
 import org.contextmapper.dsl.refactoring.henshin.Refactoring;
+import org.contextmapper.tactic.dsl.tacticdsl.DomainObject;
 import org.eclipse.xtext.EcoreUtil2;
 
 import com.google.common.collect.Lists;
@@ -70,8 +71,13 @@ protected void doRefactor() {
 			agg2 = agg1Opt.get();
 		}
 
+		// precondition check, may throw exception
 		checkForPossibleDomainObjectNameClashes(agg1, agg2);
 
+		// ensure there is only one aggregate root
+		if (containsAggregateRoot(agg1))
+			changeAggregateRootsToNormalObjects(agg2);
+
 		// move content from agg2 to agg1
 		agg1.getConsumers().addAll(agg2.getConsumers());
 		agg1.getDomainObjects().addAll(agg2.getDomainObjects());
@@ -105,6 +111,22 @@ private void checkForPossibleDomainObjectNameClashes(Aggregate aggregate1, Aggre
 					+ String.join(", ", commonDomainObjectNames));
 	}
 
+	/**
+	 * Sets aggregateRoot flag to false for all objects in given aggregate
+	 */
+	private void changeAggregateRootsToNormalObjects(Aggregate aggregate) {
+		getAggregateRoots(aggregate).forEach(o -> o.setAggregateRoot(false));
+	}
+
+	private boolean containsAggregateRoot(Aggregate aggregate) {
+		return !getAggregateRoots(aggregate).isEmpty();
+	}
+
+	private List<DomainObject> getAggregateRoots(Aggregate aggregate) {
+		return aggregate.getDomainObjects().stream().filter(o -> o instanceof DomainObject).map(o -> (DomainObject) o).filter(o -> o.isAggregateRoot())
+				.collect(Collectors.toList());
+	}
+
 	private List<Aggregate> getAllAggregates() {
 		return EcoreUtil2.<Aggregate>getAllContentsOfType(model, Aggregate.class);
 	}