Catch unhandled promise rejections during tests #4032
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Listen to the unhandledRejection event when running tests, catching promises who got rejected without being cared for, and failing the test in which said promises were left unhandled. This is only part of handling unhandled rejections, some things not yet included are: - Handling unhandled rejections outside spec tests (e.g. testhooks) - Making it work in a browser - Amend error messages which reference unhandled rejections - Testing the new signature of the `Runner.prototype.uncaught` method If this commit looks nice enough, a future commit will amend these shortcomings.
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@Zirak thanks. |
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Description of the Change
Listen to the unhandledRejection event when running tests, catching promises who
got rejected without being cared for, and failing the test in which said
promises were left unhandled.
Alternate Designs
AFAIK, this is the cleanest way to gracefully capture unhandled rejections.
Why should this be in core?
This changes how tests are run in mocha, and provides a nice parallel to the
existing
allowUncaughtoption.Benefits
Async tests which now trigger, by themselves or down their call tree,
promises left unresolved now silently pass, with a scary stack trace printed in
the console. For existing issues, see #2640 and #2785 (among others).
Possible Drawbacks
This is only part of handling unhandled rejections, some things not yet included
are:
Runner.prototype.uncaughtmethodallow-uncaughtIf this commit looks interesting enough, a future commit will amend these shortcomings.
Applicable issues
This may be a breaking change. Tests passing with unhandled rejections will fail starting with this change.