add callback message sende tests.

test/DotNetCore.CAP.Test/CallbackMessageSenderTest.cs

+using System;
+using System.Threading.Tasks;
+using DotNetCore.CAP.Abstractions;
+using DotNetCore.CAP.Internal;
+using DotNetCore.CAP.Models;
+using Microsoft.Extensions.DependencyInjection;
+using Moq;
+using Xunit;
+
+namespace DotNetCore.CAP.Test
+{
+    public class CallbackMessageSenderTest
+    {
+        private IServiceProvider _provider;
+        private Mock<ICallbackPublisher> _mockCallbackPublisher;
+        private Mock<IContentSerializer> _mockContentSerializer;
+        private Mock<IMessagePacker> _mockMessagePack;
+
+        public CallbackMessageSenderTest()
+        {
+            _mockCallbackPublisher = new Mock<ICallbackPublisher>();
+            _mockContentSerializer = new Mock<IContentSerializer>();
+            _mockMessagePack = new Mock<IMessagePacker>();
+
+            var services = new ServiceCollection();
+            services.AddTransient<CallbackMessageSender>();
+            services.AddLogging();
+            services.AddSingleton(_mockCallbackPublisher.Object);
+            services.AddSingleton(_mockContentSerializer.Object);
+            services.AddSingleton(_mockMessagePack.Object);
+            _provider = services.BuildServiceProvider();
+        }
+
+        [Fact]
+        public async void SendAsync_CanSend()
+        {
+            // Arrange
+            _mockCallbackPublisher
+                .Setup(x => x.PublishAsync(It.IsAny<CapPublishedMessage>()))
+                .Returns(Task.CompletedTask).Verifiable();
+
+            _mockContentSerializer
+                .Setup(x => x.Serialize(It.IsAny<object>()))
+                .Returns("").Verifiable();
+
+            _mockMessagePack
+                .Setup(x => x.Pack(It.IsAny<CapMessage>()))
+                .Returns("").Verifiable();
+
+            var fixture = Create();
+
+            // Act
+            await fixture.SendAsync(null, null, Mock.Of<object>());
+
+            // Assert
+            _mockCallbackPublisher.VerifyAll();
+            _mockContentSerializer.Verify();
+            _mockMessagePack.Verify();
+        }
+
+        private CallbackMessageSender Create()
+            => _provider.GetService<CallbackMessageSender>();
+    }
+}
+
+namespace Samples
+{
+
+    public interface IFoo
+    {
+        int Age { get; set; }
+        string Name { get; set; }
+    }
+
+    public class FooTest
+    {
+        [Fact]
+        public void CanSetProperty()
+        {
+            var mockFoo = new Mock<IFoo>();
+            mockFoo.Setup(x => x.Name).Returns("NameProerties");
+
+            Assert.Equal("NameProerties", mockFoo.Object.Name);
+        }
+    }
+
+}