chore: save compiled output for test suites

[tanhauhau]

Unifying the test helper to save the compiled output for:

• ssr
• runtime
• hydration

use the register.extension to also save the compiled output to filesystem.

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Updated 2022-10-14

• the output will only be saved when the test fails.
  • when compiling with register.extension in the test, we will record the compiled output in a cache
  • only write cache into the file when the test fails
  • will clear the cache for each test

[Conduitry]

It'd be nice not to have another flag. Could we just generate them unless process.env.CI is set, or do they take long enough that we wouldn't want to generate them every time when running tests locally? What if we just generated them for failing tests?

[tanhauhau]

Good suggestion for just generate it for failing test.
Probably this can replace the existing console out of the compiled code when fail

[tanhauhau]

Right now it is compiled twice if we save the output to file. Wonder is it okay if I save to file during the require.extension?

[Conduitry]

The require hook wouldn't know whether the test failed, would it?

I think removing the existing console.log of the compiled code for failing tests makes sense.

[tanhauhau]

Yea it wouldn't know

[tanhauhau]

The reason I added a flag, is that without the flag, it would compile the code twice, once for require extensions, once for saving to file, and probably thrice when console out for failing case

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[dummdidumm]

With the idea of having ESM only for Svelte 4, I'm wondering how much long-livety this change this has. But all checks pass and changes seem to look good to me, so maybe it doesn't hurt. Will wait for other maintainers to chime before deciding.

[benmccann]

should these methods be named with the underscore convention like set_compile_options?

[Rich-Harris]

Closing, as compiled output is saved to disk on the main branch