Add ol.source.Vector#isEmpty

src/ol/source/vectorsource.js

@@ -166,6 +166,14 @@ ol.source.Vector.prototype.handleFeatureChange_ = function(event) {
 };
 
 
+/**
+ * @return {boolean} Is empty.
+ */
+ol.source.Vector.prototype.isEmpty = function() {
+  return this.rBush_.isEmpty();
+};
+
+
 /**
  * @param {ol.Feature} feature Feature.
  */

test/spec/ol/source/vectorsource.test.js

@@ -37,6 +37,14 @@ describe('ol.source.Vector', function() {
 
     });
 
+    describe('#isEmpty', function() {
+
+      it('returns true', function() {
+        expect(vectorSource.isEmpty()).to.be(true);
+      });
+
+    });
+
     describe('#addFeature', function() {
 
       it('can add a single point feature', function() {
@@ -103,6 +111,14 @@ describe('ol.source.Vector', function() {
 
     });
 
+    describe('#isEmpty', function() {
+
+      it('returns false', function() {
+        expect(vectorSource.isEmpty()).to.be(false);
+      });
+
+    });
+
     describe.skip('#removeFeature', function() {
 
       it('works as expected', function() {