Allow provider to be a context manager (sync/async)

[fzyukio]

Allow a provider to be used as context manager

Problem statement:

• A variable provided through context manager is useful in case it is a resource that needs to be cleaned up immediately after the caller has finished. Example of this is a PGBouncer session.
• Bind a class to an instance of a context manager (through bind or bind_to_constructor) or to a function decorated as a context manager leads to the context manager to be used as is, not via with statement

Proposed change:

• In async_injection_wrapper and injection_wrapper: extract the provided instances from kwargs if they are subclasses of AbstractContextManager or AbstractAsyncContextManager
• Stack them up in a list (or two lists in case of async - we allow async func to be a mixture of sync and async ContextManagers )
• Before executing the function, use ExitStack (and/or AsyncExitStack) to enter all contexts, the return values are updated to kwargs and finally sent to the function

Testing

• One new unittest added

[ivankorobkov]

Hi!

Quite an interesting change 👍. Never thought about such a case. Thank you.
Could you please add comments to your code, explaining what it does? As you did in the pull request description.

Then I can merge PR and release the next version.

[fzyukio]

Hi @ivankorobkov thanks for checking it out. I've restructured it a bit and added some comments.

[ivankorobkov]

Hi, thank you.

I'll merge it tomorrow and make the next release.

[ivankorobkov]

Done https://pypi.org/project/inject/5.2.0/

[fzyukio]

@ivankorobkov Awesome! Thanks a lot for your quick action 👍