Function callback

test/openlayers/overlay/GraphicSpec.js:621–624

(a, b)

          //1、当鼠标点击在三叶草叶子内时,得到要素,调用高亮函数
          var innerCoors = [25.576171875, -27.158203125];
          var callback = function (a, b) {
            expect(b).toNotBe(null);
            expect(a.coordinate).toBe([25.576171875, -27.158203125]);
          };
          graphicLayer.getSource()._forEachFeatureAtCoordinate(innerCoors, resolution, callback, evtPixel);
          spyOn(graphicLayer, '_highLight');
          expect(graphicLayer.getSource()._highLight).toHaveBeenCalled();