Test throwing exceptions

[carloslancha]

In our components there're some params that are required. In those cases if the param is not passed the component throws an exception.

If we test that like in https://github.com/metal/metal-clay-components/blob/master/packages/clay-alert/src/__tests__/ClayAlert.js#L207 tests passes but in console appears the expected error.

Should we test those cases? If yes, we have to update all our tests with this and find out a way to hide those errors from the logs (like stubbing console.error). If not, we need to remove those tests from ClayAlert and ClayNavbar.

What do you guys think?