Enforces Type Check on TextRun Type

source/dotnet/Library/AdaptiveCards/AdaptiveInlinesConverter.cs

@@ -35,6 +35,10 @@ public override object ReadJson(JsonReader reader, Type objectType, object exist
                 else
                 {
                     JObject jobj = (JObject)obj;
+                    if (jobj.Value<string>("type") != AdaptiveTextRun.TypeName)
+                    {
+                        throw new AdaptiveSerializationException($"Property 'type' must be '{AdaptiveTextRun.TypeName}'");
+                    }
                     arrayList.Add((IAdaptiveInline)jobj.ToObject(typeof(AdaptiveTextRun)));
                 }
             }

source/dotnet/Test/AdaptiveCards.Test/AdaptiveCardApiTests.cs

@@ -1197,5 +1197,40 @@ public void TestImplicitImageType()
 
             StringAssert.Contains(ex.Message, "The value \"AdaptiveCards.AdaptiveUnknownElement\" is not of type \"AdaptiveCards.AdaptiveImage\" and cannot be used in this generic collection.");
         }
+
+        [TestMethod]
+        public void TestParsingRichTextBlockWithInvalidInlineType()
+        {
+            // card with invalid inline type
+            var invalidCard =
+            @"{
+                  ""$schema"": ""http://adaptivecards.io/schemas/adaptive-card.json"",
+                            ""type"": ""AdaptiveCard"",
+                  ""version"": ""1.2"",
+                  ""body"": [
+                    {
+                      ""type"": ""RichTextBlock"",
+                      ""inlines"": [
+                        {
+                          ""type"": ""TextRun"",
+                          ""text"": ""You did exactly what you had to do. You considered all your options, you tried every alternative and then you made the hard choice. The Enterprise computer system is controlled by three primary main processor cores, cross-linked with a redundant melacortz ramistat, fourteen kiloquad interface modules. I think you've let your personal feelings cloud your judgement. Flair is what marks the difference between artistry and mere competence. They were just sucked into space. We have a saboteur aboard. When has justice ever been as simple as a rule book? Your shields were failing, sir. Travel time to the nearest starbase? Sorry, Data. I'm afraid I still don't understand, sir. How long can two people talk about nothing? Wait a minute - you've been declared dead. You can't give orders around here. You're going to be an interesting companion, Mr. Data. Our neural pathways have become accustomed to your sensory input patterns. Fear is the true enemy, the only enemy. The Federation's gone; the Borg is everywhere! Computer, lights up!""
+                        },
+                        {
+                          ""type"": ""who cares???"",
+                          ""text"": ""You did exactly what you had to do. You considered all your options, you tried every alternative and then you made the hard choice. The Enterprise computer system is controlled by three primary main processor cores, cross-linked with a redundant melacortz ramistat, fourteen kiloquad interface modules. I think you've let your personal feelings cloud your judgement. Flair is what marks the difference between artistry and mere competence. They were just sucked into space. We have a saboteur aboard. When has justice ever been as simple as a rule book? Your shields were failing, sir. Travel time to the nearest starbase? Sorry, Data. I'm afraid I still don't understand, sir. How long can two people talk about nothing? Wait a minute - you've been declared dead. You can't give orders around here. You're going to be an interesting companion, Mr. Data. Our neural pathways have become accustomed to your sensory input patterns. Fear is the true enemy, the only enemy. The Federation's gone; the Borg is everywhere! Computer, lights up!""
+                        }
+                      ]
+                    }
+                  ]
+            }";
+
+            var ex = Assert.ThrowsException<AdaptiveSerializationException>(() =>
+            {
+                AdaptiveCard.FromJson(invalidCard);
+            });
+
+
+            StringAssert.Contains(ex.Message, "Property 'type' must be 'TextRun'");
+        }
     }
 }