Have assertion / test run after all tests have completed

[rhysmm]

I would like to have a test run after all other tests have completed. Currently, I'm doing something like this in the support/index.js file:

// support/index.js
after(() => {
    ...
    expect(someCondition);
});

This does almost exactly what I want. However, if the assertion fails, then the test which was last run fails. Ideally, I'd like to have a "new" test fail when that happens. I've also tried wrapping the assertion in it/describe, e.g:

// support/index.js
after(() => {
    ...
    describe('after all tests check', () => {
           expect(someCondition);
    });
});

Which also didn't work. Does anybody have any ideas how to achieve this?