[Branches/1.0] bugfix: LayerGroup.Envelope supports inner layers with null envelope. Workitem: #35091

becio · becio · commit 592ecd163c14 · 2014-03-31T16:24:35.000Z
git-tfs-id: [https://tfs.codeplex.com/tfs/TFS01]$/SharpMap/Branches/1.0;C105578
diff --git a/SharpMap/Layers/LayerGroup.cs b/SharpMap/Layers/LayerGroup.cs
@@ -75,11 +75,19 @@ public override Envelope Envelope
         {
             get
             {
-                if (Layers.Count == 0)
-                    return null;
-                var bbox = new Envelope(Layers[0].Envelope);
-                for (int i = 1; i < Layers.Count; i++)
-                    bbox.ExpandToInclude(Layers[i].Envelope);
+                Envelope bbox = null;
+                for (int i = 0; i < Layers.Count; i++)
+                {
+                    var layerEnvelope = Layers[i].Envelope;
+                    if (layerEnvelope != null)
+                    {
+                        if(bbox == null)
+                            bbox = new Envelope(layerEnvelope);
+                        else
+                            bbox.ExpandToInclude(layerEnvelope);
+                    }
+                }
+                    
                 return bbox;
             }
         }
diff --git a/UnitTests/Layers/LayerGroupTest.cs b/UnitTests/Layers/LayerGroupTest.cs
@@ -13,7 +13,17 @@ private class DummyLayer : Layer
         {
             public override Envelope Envelope
             {
-                get { throw new NotImplementedException(); }
+                get { return null; }
+            }
+        } 
+        #endregion
+
+        #region FooLayer class
+        private class FooLayer : Layer
+        {
+            public override Envelope Envelope
+            {
+                get { return new Envelope(5, 10, 5, 10); }
             }
         } 
         #endregion
@@ -91,5 +101,32 @@ public void ReverseCoordinateTransformation_SettingValueWhenSkipIsOn_DoesNotProp
                 "LayerGroup.ReverseCoordinateTransformation should NOT propagate to inner layers because SkipTransformationPropagation was true");
         }
 #endif
+
+        [Test(Description = "Envelope returns null when the inner layer Envelope is null")]
+        public void Envelope_WhenInnerLayerEnvelopeIsNull_ReturnsNull()
+        {
+            var group = new LayerGroup("group");
+            group.Layers.Add(new DummyLayer());
+
+            Assert.That(group.Envelope, Is.Null,
+                "LayerGroup envelope should be null since we added a layer with a null envelope");
+        }
+
+        [Test(Description = "Envelope returns null when there are no layers")]
+        public void Envelope_NoInnerLayers_ReturnsNull()
+        {
+            var group = new LayerGroup("group");
+            Assert.IsNull(group.Envelope);
+        }
+
+        [Test(Description = "Envelope skips inner layers which return null envelope")]
+        public void Envelope_SomeInnerLayerWithNullEnvelope_SkipNulls()
+        {
+            var group = new LayerGroup("group");
+            group.Layers.Add(new DummyLayer());
+            group.Layers.Add(new FooLayer());
+
+            Assert.That(group.Envelope, Is.EqualTo(new Envelope(5, 10, 5, 10)));
+        }
     }
 }
