Question

We are using AutoMapper extensively in our ASP.NET MVC web applications with the AutoMapViewResult approach set out in this question. So we have actions that look like this:

public ActionResult Edit(User item)
{
    return AutoMapView<UserEditModel>(View(item));
}

This creates hidden failure points in the application if the requested mapping has not been configured – in that this is not a compile time fail.

I’m looking at putting something in place to test these mappings. As this needs to test the actual AutoMapper configuration I presume this should be done as part of integration testing? Should these tests be structured per controller or per entity? What about the possibility of automatically parsing all calls to AutoMapView?

Note that we are already testing that the AutoMapper configuration is valid using AssertConfigurationIsValid, it is missing mappings that I want to deal with.

Answer 1

If your controller action looked like this:

public AutoMapView<UserEditModel> Edit(User item)
{
    return AutoMapView<UserEditModel>(View(item));
}

Then you can pretty easily, using reflection, look for all controller actions in your project. You then examine the action parameter types and the generic type parameter of your AutoMapView action result. Finally, you ask AutoMapper if it has a type map for those input/output models. AutoMapper doesn’t have a “CanMap” method, but you can use the IConfigurationProvider methods of FindTypeMapFor:

((IConfigurationProvider) Mapper.Configuration).FindTypeMapFor(null, typeof(User), typeof(UserEditModel);

Just make sure that’s not null.