Wrap the OpenAPI rust client-sdk with a mockable trait for easy testing

[edenreich]

Summary

Currently OpenAPI generator codegen is simple bad also bad, there is no straightforward to actually mock the API calls, because those functions are not generic and they only getting the configuration injected. So the only thing you can actually mock is probably the API endpoint but the network call will still occur.

Ideally there should be some kind of a trait that you can mock the implementation with automock library.

This is more of an investigation if there is a way to make this code more testable with mocks. I probably need to create additional generic layer between the client-sdk and the actual function calls.

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[edenreich]

I found out that https://github.com/oxidecomputer/progenitor wil generate a better client than what openapi standard generator would.

The gained benefits here is less code to generate, excluding explicit functions import will drastically reduce the amount of code generated. Plus it would make the code more testable because the client is being injected into the controller.

Unfortunately it's not as straightforward for using with mockall and automock for testing, but it at least encapsulate everything under a client struct so it would be easy to just inject the client into the controllers.

Perhaps further work would be needed - like writing the mocks, but still it's an improvements than using the regular openapi generator.

[edenreich]

I also found out there is a new version of the OpenAPI generator which now apparently supports traits: OpenAPITools/openapi-generator#19788