This will allow a producer of a microservice to be able to check the validity of the objects and types they are producing without having to rely on a mocking service.

A few years ago I had the experience of having a login page with two-factor auth for a client. We had to get creative.

End to end UI tests are the bane of testers and developers alike. They are slow, brittle, and need constant updates. They are also indispensable. A good automation strategy will speed up the feedback loop between a defect being introduced and that defect being detected.

Developing reliable integration tests requires you to control every part of your execution environment, from the operating system up to the source code itself.