Fixing issue 94, exception when checking for null

Author: matt-lethargic

src/GeoJSON.Net.Tests/Feature/FeatureTests.cs

@@ -196,7 +196,7 @@ public void Ctor_Creates_Properties_Collection_When_Passed_Null_Proper_Object()
             Assert.IsNotNull(feature.Properties);
             CollectionAssert.IsEmpty(feature.Properties);
         }
-        
+
         [Test]
         public void Feature_Equals_GetHashCode_Contract_Properties_Of_Objects()
         {
@@ -309,7 +309,54 @@ public void Serialized_And_Deserialized_Feature_Equals_And_Share_HashCode()
             Assert_Are_Equal(left, right); // assert id's + properties doesn't influence comparison and hashcode
         }
 
+        [Test]
+        public void Feature_Equals_Null_Issue94()
+        {
+            bool equal1 = true;
+            bool equal2 = true;
+
+            var feature = new Net.Feature.Feature(new Point(new Position(123, 12)));
+            Assert.DoesNotThrow(() =>
+            {
+                equal1 = feature.Equals(null);
+                equal2 = feature == null;
+            });
 
+            Assert.IsFalse(equal1);
+            Assert.IsFalse(equal2);
+        }
+
+        [Test]
+        public void Feature_Null_Instance_Equals_Null_Issue94()
+        {
+            var equal1 = true;
+
+            Net.Feature.Feature feature = null;
+            Assert.DoesNotThrow(() =>
+            {
+                equal1 = feature != null;
+            });
+
+            Assert.IsFalse(equal1);
+        }
+
+        [Test]
+        public void Feature_Equals_Itself_Issue94()
+        {
+            bool equal1 = false;
+            bool equal2 = false;
+
+            var feature = new Net.Feature.Feature(new Point(new Position(123, 12)));
+            Assert.DoesNotThrow(() =>
+            {
+                equal1 = feature == feature;
+                equal2 = feature.Equals(feature);
+            });
+
+            Assert.IsTrue(equal1);
+            Assert.IsTrue(equal2);
+        }
+        
         private IGeometryObject GetGeometry()
         {
             var coordinates = new List<LineString>

src/GeoJSON.Net.Tests/Feature/GenericFeatureTests.cs

@@ -1,4 +1,5 @@
-using System.Linq;
+using System.Collections.Generic;
+using System.Linq;
 using GeoJSON.Net.Feature;
 using GeoJSON.Net.Geometry;
 using Newtonsoft.Json;
@@ -56,6 +57,31 @@ public void Can_Deserialize_LineString_Feature()
             //Assert.AreEqual(456, feature.Geometry.Coordinates.Altitude);
         }
 
+        [Test]
+        public void Feature_Generic_Equals_Null_Issure94()
+        {
+            bool equal1 = true;
+            bool equal2 = true;
+
+            var point = new Point(new Position(123, 34));
+            var properties = new Dictionary<string, string>
+            {
+                {"test1", "test1val"},
+                {"test2", "test2val"}
+            };
+
+            var feature = new Feature<Point, Dictionary<string, string>>(point, properties, "testid");
+
+            Assert.DoesNotThrow(() =>
+            {
+                equal1 = feature == null;
+                equal2 = feature.Equals(null);
+            });
+
+            Assert.IsFalse(equal1);
+            Assert.IsFalse(equal2);
+        }
+
         private class TypedFeatureProps
         {
             [JsonProperty("name")]

src/GeoJSON.Net/Feature/Feature.cs

@@ -172,6 +172,9 @@ private static Dictionary<string, object> GetDictionaryOfPublicProperties(object
 
         public bool Equals(Feature<TGeometry> other)
         {
+            if (ReferenceEquals(null, other)) return false;
+            if (ReferenceEquals(this, other)) return true;
+
             return Geometry.Equals(other.Geometry);
         }