Use the layergroup's extent if no extent provided

src/ol/layer/layergroup.js

@@ -214,9 +214,13 @@ ol.layer.Group.prototype.getLayerStatesArray = function(opt_states) {
         layerState.maxResolution, ownLayerState.maxResolution);
     layerState.minResolution = Math.max(
         layerState.minResolution, ownLayerState.minResolution);
-    if (goog.isDef(ownLayerState.extent) && goog.isDef(layerState.extent)) {
+    if (goog.isDef(ownLayerState.extent)) {
-      layerState.extent = ol.extent.getIntersection(
+      if (goog.isDef(layerState.extent)) {
-          layerState.extent, ownLayerState.extent);
+        layerState.extent = ol.extent.getIntersection(
+            layerState.extent, ownLayerState.extent);
+      } else {
+        layerState.extent = ownLayerState.extent;
+      }
     }
   }
 

test/spec/ol/layer/layergroup.test.js

@@ -382,6 +382,12 @@ describe('ol.layer.Group', function() {
       maxResolution: 500,
       minResolution: 0.25
     });
+    var layer3 = new ol.layer.Layer({
+      source: new ol.source.Source({
+        projection: 'EPSG:4326'
+      }),
+      extent: [-5, -2, 5, 2]
+    });
 
     it('does not transform layerStates by default', function() {
       var layerGroup = new ol.layer.Group({
@@ -405,6 +411,29 @@ describe('ol.layer.Group', function() {
       goog.dispose(layerGroup);
     });
 
+    it('uses the layer group extent if layer has no extent', function() {
+      var groupExtent = [-10, -5, 10, 5];
+      var layerGroup = new ol.layer.Group({
+        extent: groupExtent,
+        layers: [layer1]
+      });
+      var layerStatesArray = layerGroup.getLayerStatesArray();
+      expect(layerStatesArray[0].extent).to.eql(groupExtent);
+      goog.dispose(layerGroup);
+    });
+
+    it('uses the intersection of group and child extent', function() {
+      var groupExtent = [-10, -5, 10, 5];
+      var layerGroup = new ol.layer.Group({
+        extent: groupExtent,
+        layers: [layer3]
+      });
+      var layerStatesArray = layerGroup.getLayerStatesArray();
+      expect(layerStatesArray[0].extent).to.eql(
+          ol.extent.getIntersection(layer3.getExtent(), groupExtent));
+      goog.dispose(layerGroup);
+    });
+
     it('transforms layerStates correctly', function() {
       var layerGroup = new ol.layer.Group({
         layers: [layer1, layer2],
@@ -451,6 +480,7 @@ describe('ol.layer.Group', function() {
 
     goog.dispose(layer1);
     goog.dispose(layer2);
+    goog.dispose(layer3);
 
   });
 
@@ -460,6 +490,7 @@ goog.require('goog.dispose');
 goog.require('goog.events.EventType');
 goog.require('goog.object');
 goog.require('ol.ObjectEventType');
+goog.require('ol.extent');
 goog.require('ol.layer.Layer');
 goog.require('ol.layer.Group');
 goog.require('ol.source.Source');