test(providers/microsoft): add test case for AzureIdentityCredentialAdapter.signed_session

[Lee-W]

As discussed in this stackoverflow thread, part of the lib does not support azure-identity well and need this helper class.

This PR is dependency of #33433, #33469, #33467

Add test case to signed_session which is the main function of this wrapper class

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[uranusjr]

Is it possible to test this?

[Lee-W]

Is it possible to test this?

I've run it with #33433 and succeeded. As for unit testing, I'm not that sure. Even if I add some, they might be mocking without checking anything. Is there any suggestions?

[uranusjr]

Not really, my impression is this wouldn’t be easy to test anyway, hence the question 😛

[potiuk]

Is it possible to test this?
Not really, my impression is this wouldn’t be easy to test anyway, hence the question 😛

Yes. We often do a mock-only tests and It's also important. Mock is really a representation of "How the author imagined the code would interact with the external world". Since you tested it, and you have good understanding how it works. Coding that in the form of mock is capturing that knowledge.

Imagine somene else making a change to that code 2 months from now. Or even YOURSELF doing it 2 months from now (I always try to picture future-self coming back to the code after I completely forgot what it does). If there is no mock and someone changes the behaviour accidentally, they won't notice and it might stop working accidentally. But when it fails, you will look at your test, and you will be able to quickly recall the intent you had without heavy debugging.

I really treat those tests with mocks often as description of what I thought the class in question shoudl be doing - so that I even don't have to remember it.

[Lee-W]

Is it possible to test this?
Not really, my impression is this wouldn’t be easy to test anyway, hence the question 😛

Yes. We often do a mock-only tests and It's also important. Mock is really a representation of "How the author imagined the code would interact with the external world". Since you tested it, and you have good understanding how it works. Coding that in the form of mock is capturing that knowledge.

Imagine somene else making a change to that code 2 months from now. Or even YOURSELF doing it 2 months from now (I always try to picture future-self coming back to the code after I completely forgot what it does). If there is no mock and someone changes the behaviour accidentally, they won't notice and it might stop working accidentally. But when it fails, you will look at your test, and you will be able to quickly recall the intent you had without heavy debugging.

I really treat those tests with mocks often as description of what I thought the class in question shoudl be doing - so that I even don't have to remember it.

Got it. Thanks @potiuk for such a detailed response. I'll try to add some mock tests tomorrow

[Lee-W]

Hi @potiuk @uranusjr , I tried to add a test in this PR. The original class is accidentally merged into the main branch in another PR. Could you please check whether such test looks good. Thanks!

[potiuk]

LGTM