fix(rules): allow TextAnnotation <-> Data(Store|Object) connection

Closes #687

lib/features/rules/BpmnRules.js

@@ -190,22 +190,6 @@ function isTextAnnotation(element) {
   return is(element, 'bpmn:TextAnnotation');
 }
 
-function isArtifact(element) {
-  return isAny(element, [
-    'bpmn:DataObjectReference',
-    'bpmn:DataStoreReference',
-    'bpmn:Group',
-    'bpmn:TextAnnotation'
-  ]);
-}
-
-function isDataObject(element) {
-  return isAny(element, [
-    'bpmn:DataObjectReference',
-    'bpmn:DataStoreReference'
-  ]);
-}
-
 function isCompensationBoundary(element) {
   return is(element, 'bpmn:BoundaryEvent') &&
          hasEventDefinition(element, 'bpmn:CompensateEventDefinition');
@@ -714,6 +698,22 @@ function canResize(shape, newBounds) {
   return false;
 }
 
+/**
+ * Check, whether one side of the relationship
+ * is a text annotation.
+ */
+function isOneTextAnnotation(source, target) {
+
+  var sourceTextAnnotation = isTextAnnotation(source),
+      targetTextAnnotation = isTextAnnotation(target);
+
+  return (
+    (sourceTextAnnotation || targetTextAnnotation) &&
+    (sourceTextAnnotation !== targetTextAnnotation)
+  );
+}
+
+
 function canConnectAssociation(source, target) {
 
   // do not connect connections
@@ -726,12 +726,13 @@ function canConnectAssociation(source, target) {
     return true;
   }
 
-  // only connect artifacts with other BPMN (graphical) elements
-  // connect if different parent
-  return ((isArtifact(source) && !isDataObject(source) && !isArtifact(target)) ||
-          (!isArtifact(source) && isArtifact(target) && !isDataObject(target))) &&
-         !isParent(target, source) &&
-         !isParent(source, target);
+  // don't connect parent <-> child
+  if (isParent(target, source) || isParent(source, target)) {
+    return false;
+  }
+
+  // allow connection of associations between <!TextAnnotation> and <TextAnnotation>
+  return isOneTextAnnotation(source, target);
 }
 
 function canConnectMessageFlow(source, target) {

test/spec/features/rules/BpmnRulesSpec.js

@@ -207,6 +207,50 @@ describe('features/modeling/rules - BpmnRules', function() {
     }));
 
 
+    it('connect DataObjectReference -> TextAnnotation', inject(function() {
+
+      expectCanConnect('DataObjectReference', 'TextAnnotation', {
+        sequenceFlow: false,
+        messageFlow: false,
+        association: true,
+        dataAssociation: false
+      });
+    }));
+
+
+    it('connect TextAnnotation -> DataObjectReference', inject(function() {
+
+      expectCanConnect('TextAnnotation', 'DataObjectReference', {
+        sequenceFlow: false,
+        messageFlow: false,
+        association: true,
+        dataAssociation: false
+      });
+    }));
+
+
+    it('connect DataStoreReference -> TextAnnotation', inject(function() {
+
+      expectCanConnect('DataStoreReference', 'TextAnnotation', {
+        sequenceFlow: false,
+        messageFlow: false,
+        association: true,
+        dataAssociation: false
+      });
+    }));
+
+
+    it('connect TextAnnotation -> DataStoreReference', inject(function() {
+
+      expectCanConnect('TextAnnotation', 'DataStoreReference', {
+        sequenceFlow: false,
+        messageFlow: false,
+        association: true,
+        dataAssociation: false
+      });
+    }));
+
+
     it('connect StartEvent_None -> DataStoreReference', inject(function() {
 
       expectCanConnect('StartEvent_None', 'DataStoreReference', {