Make unit tests run in a browser

[peaBerberian]

This mega-PR rewrites unit tests so they can be run in a web browser (for now Chrome + Firefox), through webdriverio - just like our integration and memory tests.

This allows us to run unit tests in the actual environment where the RxPlayer will run and to have a common script + environment for unit, integration and memory tests, thus simplifying the project.

The main difficulty was linked to our over-reliance on vitest's doMock+importActual functions, the second which has a different behavior when run in a web browser: multiple importActual calls in the same test file won't re-evaluate that imported file. This means that doMock performed in-between importActual calls for the same file won't have an impact on that file.

This might be fixed in the future, but I wanted to see how most people succeeded to run vitest in a browser. It seems that relying on a top-level mock function is much more idiomatic, while relying on the hoisted function to also declare hoisted mocks whose implementation can change in-between tests.

Though, to ensure portability between test frameworks if we ever change it (JavaScript is like that sometimes), I try to limit reliance on that vitest-specific vi.mock/vi.hoisted concept, by prefering just mocking through only the more portable spyOn when possible.

[github-actions]

✅ Automated performance checks have passed on commit 0eab5c1dc4688f903aedfd3a01246dea2c786019 with the base branch dev.

Details

Performance tests 1st run output

No significative change in performance for tests:

Name	Mean	Median
loading	24.84ms -> 25.17ms (-0.329ms, z: 1.10615)	35.25ms -> 35.40ms
seeking	382.39ms -> 389.69ms (-7.304ms, z: 0.32176)	16.50ms -> 16.55ms
audio-track-reload	31.52ms -> 31.53ms (-0.006ms, z: 0.28477)	46.95ms -> 46.95ms
cold loading multithread	50.50ms -> 49.86ms (0.637ms, z: 10.80065)	74.85ms -> 73.65ms
seeking multithread	44.04ms -> 51.40ms (-7.360ms, z: 0.17874)	19.50ms -> 19.50ms
audio-track-reload multithread	30.12ms -> 30.01ms (0.110ms, z: 1.15136)	43.95ms -> 43.95ms
hot loading multithread	19.81ms -> 19.68ms (0.131ms, z: 3.30380)	28.95ms -> 28.80ms

[github-actions]

✅ Automated performance checks have passed on commit e2d83bde9beb549b312bfcf12f97cd34c0de9958 with the base branch dev.

Details

Performance tests 1st run output

No significative change in performance for tests:

Name	Mean	Median
loading	24.16ms -> 24.36ms (-0.202ms, z: 0.65429)	34.35ms -> 34.35ms
seeking	432.05ms -> 433.34ms (-1.282ms, z: 0.26023)	1515.90ms -> 1515.45ms
audio-track-reload	31.04ms -> 31.04ms (0.002ms, z: 0.01204)	46.50ms -> 46.35ms
cold loading multithread	49.63ms -> 49.07ms (0.561ms, z: 12.68410)	73.50ms -> 72.60ms
seeking multithread	44.33ms -> 50.97ms (-6.637ms, z: 0.38089)	18.90ms -> 18.90ms
audio-track-reload multithread	29.70ms -> 29.64ms (0.067ms, z: 1.46123)	43.50ms -> 43.35ms
hot loading multithread	19.41ms -> 19.24ms (0.175ms, z: 5.36577)	28.50ms -> 28.20ms