Moq: Return mock object with most implementation created

I want to mock my Repository object in such a way that it can still do actual DB retrieve operations. Only for Saving operations, I wanted to setup to return mock data since I don't want it to save into the DB.

How开发者_开发技巧 should I do it?

Thanks.

Maybe you should make your Save operation virtual and override it in a subclass which you use in your tests rather than using Moq?

First of all, your unit tests should never actually go out to the database (it is all right for integration tests, but that is a larger topic). What you want to do is pretty straightforward with Moq, though:

public class MyRepo
{
      public virtual string Save(MyClass foo)
      {
          // perform save...
      }
 }

 public class MyService
 {
       public MyRepo Repo { get; set; }

       public string VerifyAndSave(MyClass foo)
       {
            // verify foo...
            return new Repo.Save(foo);
       }
 }

 public class MyClass()
 {
      public string SomeData { get; set; }
 }

Notice the virtual modifiers on the methods--these are important for Moq to be able to stub them.

In your tests you could then do something like this:

 [TestClass]
 public class SomeTests
 { 
     private Mock<MyRepo> MockRepo { get; set; }
     private MyService Target { get; set; }

     [TestInitialize]
     public void Setup()
     {
         MockRepo = new Mock<MyRepo>();
         Target = new MyService();
         Target.Repo = MockRepo.Object;
     }

     [TestMethod]
     public void MyTest()
     {
           const string expectedOutput = "SAVED";
           MyClass exampleData = new MyClass();

           MockRepo.Setup(x => x.Save(It.IsAny<MyClass>())).Returns(expectedOutput);

           Target.VerifyAndSave(exampleData);

           MockRepo.Verify(x => x.Save(It.IsAny<MyClass>()));
     }
 }

The chained calls of Setup and Returns in this case would guarantee that the calling method (i.e. VerifyAndSave) would see the value that you specified--"SAVED" in this case.

For more examples, take a look at the Moq quickstart docs.