Increase tests cases coverage and introduce e2e tests

[darkowic]

Test automation is crucial for efficient and reliable delivery of a library. We've noticed that the test coverage of the oidc-client is pretty poor — only ~29% of statements are covered. We see that PRs must not necessarily must be provided with appropriate tests before they get merged and this decreases the credibility of the library. Also, there are no e2e tests and the maintainer runs the tests manually for more advanced cases.

I want to propose coming up with a plan on how to improve that matter. Have you ever thought about how to do this better?

[jafin]

PR's are always welcome. ❤️

[guillaume-chervet]

Hi @darkowic ,
It is really a good point. I am lacking of time.
For now i never publish a version whithout testing it and i consume always the new version in my current web application.
Help and PRs would be awesome.