Setup a loaded image with src for TileLayer test

test/spec/ol/renderer/canvas/tilelayer.test.js

@@ -8,6 +8,18 @@ goog.require('ol.source.XYZ');
 
 
 describe('ol.renderer.canvas.TileLayer', function() {
+  var img = null;
+  beforeEach(function(done) {
+    img = new Image(1, 1);
+    img.onload = function() {
+      done();
+    };
+    img.src = 'data:image/gif;base64,' +
+      'R0lGODlhAQABAPAAAP8AAP///yH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==';
+  });
+  afterEach(function() {
+    img = null;
+  });
 
   describe('#composeFrame()', function() {
     it('uses correct draw scale when rotating (HiDPI)', function() {
@@ -45,7 +57,7 @@ describe('ol.renderer.canvas.TileLayer', function() {
           return [0, 0, 0];
         },
         getImage: function() {
-          return new Image();
+          return img;
         }
       }];
       renderer.composeFrame(frameState, layerState, context);