Microsoft Fakes Framework - Shim

I was writing the unit test cases using the Microsoft Fakes framework so thought to share my knowledge with you all. I majorly used Shim to write my test cases, so this post mostly focuses on Shim. I will write another post on Stub in coming days.

As most of you know that this is not the only one framework in market to write fake unit test cases the advantage of using this framework on the other is that you have full control on the test case. It will allow you to test your test case if some part of the application is not ready.

Why to use Shim?

The basic question will come in your mind that why to use Shim not the Stub. For me both are same and depend on the design of your application. If you are using any design pattern in your application except singleton then it will be advisable to use the Stub because it work very well with “Interfaces” and it is clearly mentioned in the Microsoft site as well.

Shim basically reduces the burden from the compiler by not making the run time call to the specific methods, it run the Shim code. So, the thumb rule is to use the stubs for the project within the visual studio IDE and use the shim for external libraries where you do not have any control.

If you are on this line then I am hoping that now you have some basic understand and use of Microsoft Fake framework. So let’s get started

Step 1. Create a new project in visual studio. For this post I used the ASP.NET MVC

Step 2. Create a new method

Step 3. Build the project

Step 4. Add Test project

Step 5. Add Microsoft Quality Tools using below nuget command

Install-Package Fakes.Contrib -Version 0.8.18200.2

Step 6. Add project library to test project and right click on the library to add fake assembly.

Step 7.  By doing the step 6, it will add fake assembly to the project

Step 8. Finally, we are ready to write the test case. Add a new class to test project and name it whatever you want and don’t forgot the add namespaces (using Microsoft.QualityTools.Testing.Fakes;

using Microsoft.VisualStudio.TestTools.UnitTesting;) and decorate the class with attribute ([TestClass]).

using Microsoft.QualityTools.Testing.Fakes;

using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace UnitTestProject1

{

    [TestClass]

    public class TestClass

    {

        [TestMethod]

        public void StudentExist()

        {

            bool flgStatus = false;

            WebApplication4.Controllers.Fakes.ShimHomeController.AllInstances.StudentExistStringString = (a, b, c) =>

            {

                flgStatus = true;

                return flgStatus;

            };

            WebApplication4.Controllers.HomeController objHome = new WebApplication4.Controllers.HomeController();

            Assert.AreEqual(objHome.StudentExist("First", "Last"), flgStatus);

        }

    }

}

Step 9. Build the solution

Step 10. The last piece of work is to run the test case. Right click on the test case and select the run test case. If build successful then in test explorer to you see your test successfully executed.