mockredis | mock for redis-py

Your problem is not whether Sinon supports this or that, but rather a missing understanding of how "classes" work in Ecmascript, as shown by the attempt at stubbing constructor property in the test code. That will never work, as that property has nothing to do with how any resulting objects turn out. It is simply a reference to the function that was used to create the object. I have covered a very similar topic on the Sinon tracker that you might have interest in reading to gain some core JS foo :-) Basically, it is not possible to stub a constructor, but you can probably coerce your code to use another constructor function in its place through either DI or link seams.

As a matter of fact, a few answers down in the same thread, you will see me covering an example of how I myself designed a Redis using class to be easily testable by supporting dependency injection. You might want to check it out, as it is more or less directly applicable to your example module above.

Another technique, which you already has tried getting to work, is using link seams (using rewire). The Sinon homepage has a nice article on doing this. Both rewire and proxyquire will do the job just fine here: I think you have just complicated the matter a bit by wrapping the require statement with a mock.

Even though I am on the Sinon maintainer team, I never use the mock functionality, so I cannot tell you how to use that, as I think it obscures the testing, but to get the basic link seams working using rewire I would basically remove all the Sinon code first and get the basic case going (removing redis for a stubbed module you have created).

Only then, add Sinon code as required.

As of now MiniTest tries to guess if the passed val_or_callable is a Proc by checking whether it responds to call, cf.:

• https://apidock.com/ruby/Proc/call
• https://github.com/seattlerb/minitest/blob/b84b8176930bacb4d70d6bef476b1ea0f7c94977/lib/minitest/mock.rb#L226

Unfortunately, in this specific case Redis as well as the passed MockRedis-instance both provide a generic call-method for executing Redis commands, cf.:

• https://github.com/brigade/mock_redis/blob/master/lib/mock_redis.rb#L51

You already found the correct workaround. In this case, your only chance is to explicitly use the proc-version of stub.

Note: There are some communities using def call as a pattern with ServiceObjects in Ruby which may have a difficult time using minitest's stub. It is probably a good idea to open an issue in seattlerb/minitest.

__aexit__ needs to also be asyncronous (needs to return an awaitable):