fix(rules): disallow creating DataStoreReference if process is missing

Closes #1456

lib/features/rules/BpmnRules.js

@@ -494,6 +494,13 @@ function canDrop(element, target, position) {
     return isAny(target, [ 'bpmn:Participant', 'bpmn:Lane' ]);
   }
 
+  // disallow dropping data store reference if there is no process to append to
+  if (is(element, 'bpmn:DataStoreReference') && is(target, 'bpmn:Collaboration')) {
+    return some(getBusinessObject(target).get('participants'), function(participant) {
+      return !!participant.get('processRef');
+    });
+  }
+
   // account for the fact that data associations are always
   // rendered and moved to top (Process or Collaboration level)
   //

test/spec/features/rules/BpmnRules.collaboration-empty.bpmn

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<bpmn2:definitions xmlns:bpmn2="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" id="_biH3sOTeEeS2YerRfpjPrw" targetNamespace="http://camunda.org/schema/1.0/bpmn" exporter="Camunda Modeler" exporterVersion="1.14.0" xsi:schemaLocation="http://www.omg.org/spec/BPMN/20100524/MODEL BPMN20.xsd">
+  <bpmn2:collaboration id="Collaboration">
+    <bpmn2:participant id="Participant" name="Pool"/>
+  </bpmn2:collaboration>
+  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
+    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Collaboration">
+      <bpmndi:BPMNShape id="_BPMNShape_Participant_3" bpmnElement="Participant" isHorizontal="true">
+        <dc:Bounds x="72" y="48" width="706" height="266" />
+      </bpmndi:BPMNShape>
+    </bpmndi:BPMNPlane>
+  </bpmndi:BPMNDiagram>
+</bpmn2:definitions>

test/spec/features/rules/BpmnRulesSpec.js

@@ -123,6 +123,26 @@ describe('features/modeling/rules - BpmnRules', function() {
       expectCanCreate([task1, task2], 'SequenceFlow', false);
     }));
 
+
+    describe('empty pool', function() {
+
+      var testXML = require('./BpmnRules.collaboration-empty.bpmn');
+
+      beforeEach(bootstrapModeler(testXML, { modules: testModules }));
+
+
+      it('should not allow to drop DataStoreReference when there is no process to append to',
+        inject(function(elementFactory) {
+
+          // given
+          var dataStoreReference = elementFactory.createShape({ type: 'bpmn:DataStoreReference' });
+
+          // then
+          expectCanCreate(dataStoreReference, 'Collaboration', false);
+        })
+      );
+    });
+
   });