Supporting Multiple TestProperty with the same key value.

src/Microsoft.TestPlatform.ObjectModel/TestProperty/CustomKeyValueConverter.cs

@@ -43,14 +43,25 @@ public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo c
             {
                 using (var stream = new MemoryStream(Encoding.Unicode.GetBytes(data)))
                 {
-                    var serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(typeof(Dictionary<string, string>));
-                    var dict = serializer.ReadObject(stream) as Dictionary<string, string>;
+                    // Converting Json data to array of KeyValuePairs with duplicate keys.
+                    var serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(typeof(TraitObject[]));
+                    var listOfTraitObjects = serializer.ReadObject(stream) as TraitObject[];                                        
 
-                    return dict?.ToArray();
+                    return listOfTraitObjects.Select(i => new KeyValuePair<string, string>(i.Key, i.Value)).ToArray();;
                 }
             }
 
             return base.ConvertFrom(context, culture, value);
         }
+
+        [System.Runtime.Serialization.DataContract]
+        private class TraitObject
+        {
+            [System.Runtime.Serialization.DataMember(Name = "Key")]
+            public string Key { get; set; }
+
+            [System.Runtime.Serialization.DataMember(Name = "Value")]
+            public string Value { get; set; }
+        }
     }
 }

test/Microsoft.TestPlatform.ObjectModel.UnitTests/CustomKeyValueConverterTests.cs

@@ -60,25 +60,30 @@ public void CustomKeyValueConverterShouldDeserializeEmptyArray()
         }
 
         [TestMethod]
-        public void CustomKeyValueConverterShouldThrowOnDeserializeNullKeyOrValue()
+        public void CustomKeyValueConverterShouldDeserializeEmptyKeyOrValue()
         {
-            var json = "[{ \"Key\": null, \"Value\": \"\" }]";
+            var json = "[{ \"Key\": \"\", \"Value\": \"\" }]";
 
-            var action = new Action(() => this.customKeyValueConverter.ConvertFrom(null, CultureInfo.InvariantCulture, json));
+            var data = this.customKeyValueConverter.ConvertFrom(null, CultureInfo.InvariantCulture, json) as KeyValuePair<string, string>[];
 
-            Assert.ThrowsException<ArgumentNullException>(action);
+            Assert.AreEqual(1, data.Length);
+            Assert.AreEqual(string.Empty, data[0].Key);
+            Assert.AreEqual(string.Empty, data[0].Value);
         }
 
         [TestMethod]
-        public void CustomKeyValueConverterShouldDeserializeEmptyKeyOrValue()
+        public void CustomKeyValueConverterShouldDeserializeDuplicateKeysKvps()
         {
-            var json = "[{ \"Key\": \"\", \"Value\": \"\" }]";
+            var json = "[{ \"Key\": \"key1\", \"Value\": \"val1\" }, { \"Key\": \"key1\", \"Value\": \"val2\" }]";
 
             var data = this.customKeyValueConverter.ConvertFrom(null, CultureInfo.InvariantCulture, json) as KeyValuePair<string, string>[];
 
-            Assert.AreEqual(1, data.Length);
-            Assert.AreEqual(string.Empty, data[0].Key);
-            Assert.AreEqual(string.Empty, data[0].Value);
+            Assert.IsNotNull(data);
+            Assert.AreEqual(2, data.Length);
+            Assert.AreEqual("key1", data[0].Key);
+            Assert.AreEqual("val1", data[0].Value);
+            Assert.AreEqual("key1", data[1].Key);
+            Assert.AreEqual("val2", data[1].Value);
         }
     }
 }