The idea here is to keep the concept of _what_ we're asserting (that an email was sent)
away from the implementation of how we check that assertion
This means that tests can have a consistent api like .sentEmail(), and if we change how that function works,
we only have to update the assertion function in the MockManager
Much more cleanup to come behind the scenes, but the aim is to make the tests as clean as possible
- encapsulated concerns within individual objects
- this will allow us to refactor these into classes or move them around later
- also makes it clearer how methods like restore relate to other methods
- e.g mocks.restore() restores mocks, whilst fixtureManager.restore() restores the database
refs https://github.com/TryGhost/Toolbox/issues/158
- Moving common mocking/stubbing/spying logic into an outside utils module allows test suites to keep agnostic towards which framework powers mocking etc. Should also substitute email service stubbing used in multiple places
- Bonus, got rid of should dependency, which is deprecated
