The deploy tests need jsDelivr mocks

[mbostock]

There’s a bug with the deploy tests that they require that the build tests have previously run and cached the responses from the jsDelivr API. So if you run the deploy tests by themselves, they fail. I need to figure out how to compose the jsDelivr API mocks with the Observable API mocks that the deploy tests need.

[mythmon]

For the AI assist project, I built a set of helper functions that implement a Playwright-style dependency-injection system for the tests. The key benefits that I saw for it were that the test helpers (like the jsDelivr and Observable API mocks) could have their own dependencies, and that they could automatically clean up after themselves (another problem we have in the current situation).

I think that using that this "test helper" system could help with composing the HTTP mocks because both mocks could delegate making undici interceptor to another test helper that could smartly only make one per test, and automatically deregister it after all mocks are done.

Is that something that you'd be amenable to? I can sketch out a PR for it.

Edit: Here is the code I did for the AI assist project: https://github.com/observablehq/observablehq/tree/main/notebook-prompts/test/fixtures. It isn't well demonstrated there because there aren't a lot of tests, but I think it gets the point across.

[cinxmo]

@mythmon is this resolved with #552?

[mythmon]

I think so, yes. I'll admit I didn't actually explicitly test though.