From 890e4661619e960769af5bed8ff30aeee0418ac8 Mon Sep 17 00:00:00 2001
From: Maciej Barelkowski <maciej.barelkowski@camunda.com>
Date: Mon, 24 Jun 2019 13:16:11 +0200
Subject: [PATCH] fix(bpmn-rules): allow to drop Boundary Events only on
 containers

Closes https://github.com/bpmn-io/bpmn-js/issues/1095
---
 lib/features/rules/BpmnRules.js           | 13 +++++++++----
 test/spec/features/rules/BpmnRulesSpec.js |  4 ++++
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/lib/features/rules/BpmnRules.js b/lib/features/rules/BpmnRules.js
index d2e14bb0..34f4d891 100644
--- a/lib/features/rules/BpmnRules.js
+++ b/lib/features/rules/BpmnRules.js
@@ -479,10 +479,9 @@ function canDrop(element, target, position) {
     return is(target, 'bpmn:Participant') || is(target, 'bpmn:Lane');
   }
 
-  if (is(element, 'bpmn:BoundaryEvent')) {
-    return getBusinessObject(element).cancelActivity && (
-      hasNoEventDefinition(element) || hasCommonBoundaryIntermediateEventDefinition(element)
-    );
+  // disallow dropping boundary events which cannot replace with intermediate event
+  if (is(element, 'bpmn:BoundaryEvent') && !isDroppableBoundaryEvent(element)) {
+    return false;
   }
 
   // drop flow elements onto flow element containers
@@ -517,6 +516,12 @@ function canDrop(element, target, position) {
   return false;
 }
 
+function isDroppableBoundaryEvent(event) {
+  return getBusinessObject(event).cancelActivity && (
+    hasNoEventDefinition(event) || hasCommonBoundaryIntermediateEventDefinition(event)
+  );
+}
+
 function canPaste(tree, target) {
   var topLevel = tree[0],
       participants;
diff --git a/test/spec/features/rules/BpmnRulesSpec.js b/test/spec/features/rules/BpmnRulesSpec.js
index 03a3e9e5..d3ce9ab1 100644
--- a/test/spec/features/rules/BpmnRulesSpec.js
+++ b/test/spec/features/rules/BpmnRulesSpec.js
@@ -470,6 +470,10 @@ describe('features/modeling/rules - BpmnRules', function() {
       });
     }));
 
+
+    it('drop BoundaryEvent -> Task', function() {
+      expectCanDrop('BoundaryEvent_on_SubProcess', 'Task_in_OtherProcess', false);
+    });
   });