diff --git a/test/spec/ol/array.test.js b/test/spec/ol/array.test.js
index d9a457565d..ae0e70f514 100644
--- a/test/spec/ol/array.test.js
+++ b/test/spec/ol/array.test.js
@@ -353,6 +353,54 @@ describe('ol.array', function() {
       expect(ol.array.equals([{}], [{}])).to.be(false);
     });
   });
+  describe('extend', function() {
+    it('extends an array in place with an array', function() {
+      var a = [0, 1];
+      ol.array.extend(a, [2, 3]);
+      expect(a).to.eql([0, 1, 2, 3]);
+    });
+    it('extends an array in place with a number', function() {
+      var a = [0, 1];
+      ol.array.extend(a, 2);
+      expect(a).to.eql([0, 1, 2]);
+    });
+    it('extends an array in place with an arraylike object', function() {
+      var a = [0, 1];
+      var arrayLikeObject = {0: 2, 1: 3, length: 2};
+      ol.array.extend(a, arrayLikeObject);
+      expect(a).to.eql([0, 1, 2, 3]);
+    });
+    it('extends an array in place with an empty arraylike object', function() {
+      var a = [0, 1];
+      var arrayLikeObject = {length: 0};
+      ol.array.extend(a, arrayLikeObject);
+      expect(a).to.eql([0, 1]);
+    });
+    it('extends an array in place with a big array', function() {
+      var a = [];
+      var i = 500000; // original test has 1.000.000, but that was to slow
+      var bigArray = Array(i);
+      while (i--) {
+        bigArray[i] = i;
+      }
+      ol.array.extend(a, bigArray);
+      expect(a).to.eql(bigArray);
+    });
+    it('extends an array in place with arguments', function() {
+      var f = function() {
+        return arguments;
+      };
+      var a = [0];
+      ol.array.extend(a, f(1, 2, 3));
+      expect(a).to.eql([0, 1, 2, 3]);
+    });
+    it('extends an array with a NodeList (from querySelectorAll)', function() {
+      var a = [];
+      ol.array.extend(a, document.querySelectorAll('head'));
+      expect(a.length).to.be(1);
+      expect(a[0]).to.be(document.head);
+    });
+  });
 
   describe('linearFindNearest', function() {
     it('returns expected value', function() {