Add more debug assertions around flakey test

Author: Mpdreamz

src/Tests/Tests/Search/MultiSearch/MultiSearchLowLevelPostDataTests.cs

@@ -76,7 +76,8 @@ private static void AssertResponse(DynamicResponse response)
 
 			var b = response.Body;
 			List<object> responses = b.responses;
-			responses.Count().Should().Be(4);
+			response.Should().NotBeNull("{0}", response.DebugInformation);
+			responses.Count().Should().Be(4, "{0}", response.DebugInformation);
 
 			object r = b.responses[0];
 			r.Should().NotBeNull();