Merge pull request #760 from OpenGeoscience/missing-event-handler

Add a warning if an event handler is missing.

src/object.js

@@ -15,6 +15,8 @@ var object = function () {
     return new object();
   }
 
+  var util = require('./util');
+
   var m_this = this,
       m_eventHandlers = {},
       m_idleHandlers = [],
@@ -75,6 +77,10 @@ var object = function () {
       });
       return m_this;
     }
+    if (!util.isFunction(handler)) {
+      console.warn('Handler for ' + event + ' is not a function', handler, m_this);
+      return m_this;
+    }
     if (!m_eventHandlers.hasOwnProperty(event)) {
       m_eventHandlers[event] = [];
     }
@@ -107,7 +113,11 @@ var object = function () {
 
     if (m_eventHandlers.hasOwnProperty(event)) {
       m_eventHandlers[event].forEach(function (handler) {
-        handler.call(m_this, args);
+        try {
+          handler.call(m_this, args);
+        } catch (err) {
+          console.warn('Event handler for ' + event + ' threw an error', err);
+        }
       });
     }
 

tests/cases/object.js

@@ -199,6 +199,33 @@ describe('geo.object', function () {
       expect(foo.ncalls).toBe(3);
     });
 
+    it('Test a non-function handler', function () {
+      sinon.stub(console, 'warn', function () {});
+      var obj = new geo.object(),
+          evtData = {},
+          handler = new CallCounter(evtData);
+
+      obj.geoOn('event1', undefined);
+      expect(console.warn.calledOnce);
+      obj.geoOn('event1', handler.call);
+      obj.geoTrigger('event1', evtData);
+      expect(handler.ncalls).toBe(1);
+      console.warn.restore();
+    });
+
+    it('Test a handler that has an error', function () {
+      sinon.stub(console, 'warn', function () {});
+      var obj = new geo.object(),
+          evtData = {},
+          handler = new CallCounter(evtData);
+
+      obj.geoOn('event1', function () { throw new Error('fail'); });
+      obj.geoOn('event1', handler.call);
+      obj.geoTrigger('event1', evtData);
+      expect(handler.ncalls).toBe(1);
+      expect(console.warn.calledOnce);
+      console.warn.restore();
+    });
   });
 
 });