tests(starter): add tests for oauth2 and identity provider

[joaquinfelici]

related to #4567

[psavidis]

Hey @joaquinfelici,

Here is my review:

• Questions: I've got one question
• Observations: Verified the tests that rely on the existence of beans (ref1, ref)
• Tests: According to the Testing Best Practices, the tests should follow a shouldReturnSomething naming convention. Instead of commenting on each test, i've added one example which could have also been more helpful to me to understand the testing logic.

My next step recommendation: Let's pair up to add a few comments on the when / then sections, adapt the names and answer questions.

[psavidis]

Hey @joaquinfelici,

Here is my review:

• Questions: I've got one question
• Observations: Verified the tests that rely on the existence of beans (ref1, ref)
• Tests: According to the Testing Best Practices, the tests should follow a shouldReturnSomething naming convention. Instead of commenting on each test, i've added one example which could have also been more helpful to me to understand the testing logic.

My next step recommendation: Let's pair up to add a few comments on the when / then sections, adapt the names and answer questions.

• We agreed with @joaquinfelici that the test naming conventions can diverge from the best practices guide as they are whitebox tests, tied to spring security and the attempt to rename them made the result worse.
• Some comments will be added to the given-when-then blocks to add context
• After that, the review is concluded and is approved.