Add test unit for null|undefined params in ol.uri

test/spec/ol/uri.test.js

@@ -62,4 +62,13 @@ describe('ol.uri.appendParams()', function() {
     expect(url).to.equal('http://example.com/foo?bar=bam&baz=bat&bop=&k=v');
   });
 
+  it('should not append null or undefined parameters to the url', function() {
+    var url = ol.uri.appendParams('http://example.com/foo', {
+      a: '1',
+      b: null,
+      c: undefined
+    });
+    expect(url).to.equal('http://example.com/foo?a=1');
+  });
+
 });