unit testing a method that uses Assembly

Question

I need to xUnit test a method that uses Assembly, specifically called with parameter Assembly.GetEntryAssembly().

But unfortunately in unit test project, the entry assembly appears to be testhost not my test project. That way I'll not be able to search my test project. Does that mean I won't be able to test this method? or is the another way to go?

Answer 1

Not all code should be tested. Extract the code where you use Assembly.GetEntryAssembly() into a separate component, something like this:

public interface IAssemblyProvider
{
      Assembly GetEntryAssembly();
}

public class AssemlbyProvider : IAssemblyProvider
{
      public Assembly GetEntryAssembly()
      {
           return Assembly.GetEntryAssembly();
      }
}

And use this abstraction in your code. No need to test this single method - we know it works, this is part of .Net framework. Then the code that you'd like to test should consume IAssemblyProvider, so you can substitute this with a stub:

// should only be visible in test project
internal class StubAssemlbyProvider : IAssemblyProvider
{
      public Assembly GetEntryAssembly()
      {
           return typeof(MyClassInEntryAssembly).Assembly;
      }
}

This way your code is tested, but you are not testing .Net framework code.