This is intended behavior, but

1. the documentation is correct in that the fixtures are run before your tests
2. it is incorrect in that the fixtures are not run before your test files load

the reason it is the way it is: it'd otherwise be unusable in a browser without adding more API surface, and we try to keep things the same between node/browser as much as possible.

this will be a problem if we allow async suites, since the suites would potentially try to use a resource (e.g. connect to a port) that a global setup fixture created... hm.

two questions:

1. does this behavior prevent you from using global fixtures?
2. if you used it as it works now, and we changed global setup fixtures to run before the test files are loaded, would that break what you're doing?

I've created #4511 to address this. I agree that the behavior should change. Hopefully there hasn't been too much adoption of the feature yet..

@boneskull thank you for addressing this.

1. does this behavior prevent you from using global fixtures?

It does, since the test files are loaded before the fixtures. I'm working in a codebase that loads configurations from a database before importing the files to start a webserver. Some of it's dependencies use these configurations on top-level code (regardless of wether that's good practice or not), so today I cannot push global fixtures to the code since it would break the CI workflow.

2. if you used it as it works now, and we changed global setup fixtures to run before the test files are loaded, would that break what you're doing?

No, in fact the behavior on watch mode is exactly that, so I've been developing that way the last few days. I understand I'll have to revert the introduction of global fixtures and wait for this to be finished in order to adopt it.

By the way, this is a great feature and it makes the test setup process so much clearer. Specially if you can delay the files being loaded, so that all code can be in the proper place. Congratulations.

I left a comment saying the setup and teardown functions weren't being called for me, they are.. I was doing

exports = {
    mochaGlobalSetup,
    mochaGlobalTeardown,
    mochaHooks,
};

instead of

exports.mochaGlobalSetup = mochaGlobalSetup;
exports.mochaGlobalTeardown = mochaGlobalTeardown;
exports.mochaHooks = mochaHooks;

too used to typescript ¯_(ツ)_/¯. Hopefully leaving this comment helps someone else?

Without this patch we were currently not able to perform integration tests for one of our bigger systems in a clean and lean way. We really hope for a merge here. Because 9 is already released.

@boneskull How is the planing about this?