fix(viewer): add priority and context arguments to events

Closes #393

lib/Viewer.js

@@ -19,7 +19,7 @@ function initListeners(diagram, listeners) {
   var events = diagram.get('eventBus');
 
   listeners.forEach(function(l) {
-    events.on(l.event, l.handler);
+    events.on(l.event, l.priority, l.handler, l.that);
   });
 }
 
@@ -331,14 +331,14 @@ Viewer.prototype.destroy = function() {
  * @param {String} event
  * @param {Function} handler
  */
-Viewer.prototype.on = function(event, handler) {
+Viewer.prototype.on = function(event, priority, handler, that) {
   var diagram = this.diagram,
       listeners = this.__listeners = this.__listeners || [];
 
-  listeners.push({ event: event, handler: handler });
+  listeners.push({ event: event, priority: priority, handler: handler, that: that });
 
   if (diagram) {
-    diagram.get('eventBus').on(event, handler);
+    diagram.get('eventBus').on(event, priority, handler, that);
   }
 };
 

test/spec/ViewerSpec.js

@@ -119,6 +119,36 @@ describe('Viewer', function() {
   });
 
 
+  describe('#on', function() {
+
+    it('should fire with given three', function(done) {
+
+      // given
+      var viewer = new Viewer({ container: container });
+
+      var xml = require('../fixtures/bpmn/empty-definitions.bpmn');
+
+      // when
+      viewer.on('foo', 1000, function() {
+        return 'bar';
+      }, viewer);
+
+      // then
+      viewer.importXML(xml, function(err) {
+        var eventBus = viewer.get('eventBus');
+
+        var result = eventBus.fire('foo');
+
+        expect(result).to.equal('bar');
+
+        done();
+      });
+
+    });
+
+  });
+
+
   describe('overlay support', function() {
 
     it('should allow to add overlays', function(done) {