chore(group-behavior): move category creation to util

lib/features/modeling/behavior/GroupBehavior.js

@@ -12,6 +12,9 @@ import {
   is
 } from '../../../util/ModelUtil';
 
+import {
+  createCategoryValue
+} from './util/CategoryUtil';
 
 /**
  * BPMN specific Group behavior
@@ -146,17 +149,8 @@ export default function GroupBehavior(eventBus, bpmnFactory, canvas, elementRegi
 
     if (is(businessObject, 'bpmn:Group') && !businessObject.categoryValueRef) {
 
-      var definitions = getDefinitions();
-
-      var categoryValue = bpmnFactory.create('bpmn:CategoryValue'),
-          category = bpmnFactory.create('bpmn:Category', {
-            categoryValue: [ categoryValue ]
-          });
-
-      // add to correct place
-      collectionAdd(definitions.get('rootElements'), category);
-      getBusinessObject(category).$parent = definitions;
-      getBusinessObject(categoryValue).$parent = category;
+      var definitions = getDefinitions(),
+          categoryValue = createCategoryValue(definitions, bpmnFactory);
 
       // link the reference to the Group
       businessObject.categoryValueRef = categoryValue;

lib/features/modeling/behavior/util/CategoryUtil.js

@@ -0,0 +1,30 @@
+import {
+  add as collectionAdd
+} from 'diagram-js/lib/util/Collections';
+
+import {
+  getBusinessObject
+} from '../../../../util/ModelUtil';
+
+/**
+ * Creates a new bpmn:CategoryValue inside a new bpmn:Category
+ *
+ * @param {ModdleElement} definitions
+ * @param {BpmnFactory} bpmnFactory
+ *
+ * @return {ModdleElement} categoryValue.
+ */
+export function createCategoryValue(definitions, bpmnFactory) {
+  var categoryValue = bpmnFactory.create('bpmn:CategoryValue'),
+      category = bpmnFactory.create('bpmn:Category', {
+        categoryValue: [ categoryValue ]
+      });
+
+  // add to correct place
+  collectionAdd(definitions.get('rootElements'), category);
+  getBusinessObject(category).$parent = definitions;
+  getBusinessObject(categoryValue).$parent = category;
+
+  return categoryValue;
+
+}