fix: export `SetupServerCommonApi` publicly

[ryanmagoon]

Implements #2072

This enables custom interceptors to be used to create a setupServer function

[kettanaito]

Thanks for looking into this, @ryanmagoon! Let me think if this is the best course of action here. I dislike that one cannot have the API of setupServer and then swap the interceptors underneath. I think that's a DX limitation that can be avoided. The SetupServerCommonApi is environment-agnostic so it won't have some Node.js-specific features like server.boundary(), which is a shame (and also quite difficult to replicate on your own).

I think instead of exposing SetupServerCommonApi, we need to come up with a way to extend SetupServerApi with the list of custom handlers.

[ryanmagoon]

Would it be clean enough to optionally allow additional interceptors to be passed into SetupServerApi constructor and setupServer? Or is there some extra typing work there around the event map

setupServer having more params will be a breaking change obv

[vishakha94]

@kettanaito Any updates on this?

[kettanaito]

I think instead of exposing the common API, we should restructure these setup classes so that each has a protected interceptor property. Protected properties can be overridden by derived classes, allowing you to create custom setup classes where you can just swap out the interceptor to any other BatchInterceptor of your choice.

class CustomSetup extends SetupServer {
  protected interceptor = new BatchInterceptor([...])
}

As the next step, we can simplify the conversion of setup classes to setupX(...handlers) APIs.

export function toSetupApi(SetupClass) {
  return (...handlers) => {
    return new SetupClass(handlers)
  }
}

This is a draft; the exact API may vary.

@ryanmagoon, would like to hear your thoughts on this. With my proposal, I'm trying to follow the "open to extension, closed to modification" principle to keep the setup APIs sane to work with.

[ryanmagoon]

Yeah that sounds way better, this is just what I had patched in to unblock myself 😅 will update

[kettanaito]

The interceptor property already exists on all those classes, just need to check if it's protected. We can iterate on the toSetupApi utility together!

[ryanmagoon]

will follow up with setup util for custom SetupServerApi classes