Ability to run test files in the same process

[sindresorhus]

Split from #1322.

… add an option to not spawn AVA test files as child-processes. Pretty much what ava/profile.js does now. I also need this for testing Electron apps, as their tester needs to inject some globals. Having such option would also fix our React/etc performance issues.

It could be a global option that when turned on would run the test files in the same process in a new script context using the vm module instead of a child process.

[jeffijoe]

This would still run each test in parallel, right?

[novemberborn]

This would still run each test in parallel, right?

Yes.

[ORESoftware]

@novemberborn yes parallel, but not in separate processes, because require('vm') doesn't spawn a separate process (...or does it?)

[sindresorhus]

because require('vm') doesn't spawn a separate process (...or does it?)

It does not. That's the whole point of this issue, to not spawn.

[tniessen]

This would still run each test in parallel, right?

Just FYI, the vm module has nothing to do with concurrency, and it is not comparable to executing tests in separate processes. There is neither strict isolation nor will any code be executed in parallel, apart from the usual event loop.

[novemberborn]

Prompted by #1631 it might be interesting to still start workers, but reuse them for different test files. We'd use vm for sandboxing. Would be good to check Jest's sandboxing approach as well.