Add end-to-end tests to CI

[twifkak]

#41 runs the unit tests for Rust & TypeScript. Add to this, something that tests that they interact correctly with each other and with the Cloudflare Worker environment. Ideas:

End-to-end tests:

• Run wrangler dev and curl localhost:8787 | dump-signedexchange -verify
• Deploy to a test environment: https://github.com/marketplace/actions/deploy-to-cloudflare-workers-with-wrangler

Integration tests for individual TS functions:

• Mock Cloudflare Worker environment: https://blog.cloudflare.com/unit-testing-worker-functions/
• Using wrangler dev: https://www.paolotagliaferri.com/test-cloudflare-workers-with-jest-wrangler-travis/
• Deploy to a test environment: https://blog.cloudflare.com/unit-testing-workers-in-cloudflare-workers/

[twifkak]

As an interim solution, maybe some almost e2e tests, like a CLI SXG generator and a shell script that pipes it to dump-signedexchange -verify.

Plus wrangler build and the fastly_compute equivalent.

[twifkak]

I'm thinking at a minimum the test plan should be a matrix of:

Accept header:

• prefers SXG
• doesn't prefer SXG

Response:

• small (<8MB) HTML
• small HTML + <meta charset=utf-8>
• small HTML + <meta charset=utf-8> + UTF-16 encoding with BOM
• large (>8MB) HTML + <meta charset=utf-8>
• small non-HTML
• large non-HTML

[twifkak]

Another possible alternative to wrangler dev is Cloudflare's Miniflare which is a local Workers emulator.