Getting a Browser.Navigation.Key for testing

[sporto]

When using Browser.application I will put the Key in my model for later use.

When testing I want to create a model, but I don't have a way to get a Key. So we cannot test functions that take Model.

Seems that a function to get a Key is necessary to test.

[evancz]

Do you mind opening this up on elm-explorations/test instead?

I don't think the API here can give dummy versions out, and I think the testing API needs to be absolutely certain that a real Key cannot escape the tests