added test for the constructor

Verifying that methods gets called is something that I've actively been removing because the tests becomes really brittle when it's used and i strongly believe that the tests becomes way to tightly coupled to the implementation.

1. If the implementation of the constructor would change to provide this information to the class in any another way this would break.
2. This tests that the methods gets called but it doesn't have a clue about what happens with the return values. It might just as well have been thrown away.
3. Due to the mocking above if anything with the Config implementation changes just slightly this will most likely be forgotten and mock an outdated implementation but the tests will still pass.