fix: disallow creating message flow without participants

Author: philippfromme

lib/features/rules/BpmnRules.js

@@ -144,7 +144,7 @@ BpmnRules.prototype.init = function() {
 
     return every(elements, function(element) {
       if (isConnection(element)) {
-        return canConnect(element.source, element.target, element);
+        return (canConnect(element.source, element.target, element) || {}).type === element.type;
       }
 
       if (element.host) {
@@ -1068,11 +1068,11 @@ function canConnectMessageFlow(source, target) {
     return false;
   }
 
-  return (
-    isMessageFlowSource(source) &&
-    isMessageFlowTarget(target) &&
-    !isSameOrganization(source, target)
-  );
+  return isMessageFlowSource(source)
+    && (is(source, 'bpmn:Participant') || !!getParent(source, 'bpmn:Participant'))
+    && isMessageFlowTarget(target)
+    && (is(target, 'bpmn:Participant') || !!getParent(target, 'bpmn:Participant'))
+    && !isSameOrganization(source, target);
 }
 
 /**

test/spec/features/rules/BpmnRulesSpec.js

@@ -58,7 +58,8 @@ describe('features/modeling/rules - BpmnRules', function() {
           sequenceFlow = elementFactory.createConnection({
             type: 'bpmn:SequenceFlow',
             source: task1,
-            target: task2
+            target: task2,
+            waypoints: []
           });
 
       // then
@@ -74,7 +75,8 @@ describe('features/modeling/rules - BpmnRules', function() {
           sequenceFlow = elementFactory.createConnection({
             type: 'bpmn:MessageFlow',
             source: task1,
-            target: task2
+            target: task2,
+            waypoints: []
           });
 
       // then