refactor unit tests

test/DotNetCore.CAP.Test/ModelBinderFactoryTest.cs

 using System.Linq;
 using System.Reflection;
+using DotNetCore.CAP.Abstractions;
 using DotNetCore.CAP.Internal;
+using Moq;
 using Xunit;
 
 namespace DotNetCore.CAP.Test
@@ -11,7 +13,8 @@ namespace DotNetCore.CAP.Test
 
         public ModelBinderFactoryTest()
         {
-            _factory = new ModelBinderFactory();
+            var serializer = Mock.Of<IContentSerializer>();
+            _factory = new ModelBinderFactory(serializer);
         }
 
         [Theory]

test/DotNetCore.CAP.Test/QueueExecutorFactoryTest.cs

@@ -16,9 +16,6 @@ namespace DotNetCore.CAP.Test
             services.AddLogging();
             services.AddOptions();
             
-            var callbackSender = Mock.Of<ICallbackMessageSender>();
-
-            services.AddSingleton(callbackSender);
             services.AddCap(x => { });
             _provider = services.BuildServiceProvider();
         }