How to create Shim for System.AppDomain class?

Question

In my code I am using AppDomain.CurrentDomain.BaseDirectory call.

In my unit test I want to fake this call, so it will always return same value for BaseDirectory property.

However, after generating fake assembly for System I can't see ShimAppDomain in my unit test. Is it becasue AppDomain is sealed class?

How can I isolate my test from AppDomain.CurrentDomain.BaseDirectory call?

For mocking using Microsoft Fakes Framework and Visual Studio 2015 Enterprise.

Answer 1

Found this solution

I. Updated content of mscorlib.fakes to

<Fakes xmlns="http://schemas.microsoft.com/fakes/2011/" Diagnostic="true">
  <Assembly Name="mscorlib" Version="4.0.0.0"/>
  <StubGeneration>
    <Clear/>
  </StubGeneration>
  <ShimGeneration>
    <Clear/>
    <Add FullName="System.AppDomain"/>
  </ShimGeneration>
</Fakes>

II. Added using System.Fakes to my Unit Test file

III. Added following to my Unit Test

using (ShimsContext.Create())
{
    string baseDir = @"My\Base\Dir";

    ShimAppDomain fakeAppDomain = new ShimAppDomain()
    {
        BaseDirectoryGet = () => { return baseDir; }
    };

    ShimAppDomain.CurrentDomainGet = () => { return fakeAppDomain; };

    string defaultDir = MyConstants.DefaultAppFolder;

    // both baseDir and defaultDir are same "My\Base\Dir"
    Assert.AreEqual(baseDir, defaultDir);
}

Constants.DefaultAppFolder property is implemented as follows

internal static class MyConstants
{
    internal static string DefaultAppFolder
    {
        get
        {
            return AppDomain.CurrentDomain.BaseDirectory;
        }
    }
}

It is quite verbose, but works.