Random ordering for mocha

  • choma

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1.2.16 years ago8 years agoMinified + gzip package size for choma in KB


Random ordering for mocha


It is very easy to accidentally create a fragile test suite by leaving lingering state after a test case, that is then inadvertently used as a precondition for a subsequent test. This can then cause problems trying to run single tests or test suites in isolation.
By executing files in a random order on each execution of a test suite the risk of accidental introduction of state is eliminated, or at least reduced, since any dependency on leftover state will result in test failures.


Pass choma as a require option to mocha, either by appending to your test command:
> mocha ./tests/ --require choma

or by adding a line to mocha.opts
--require choma


The seed used to generate the random order is output to the console when running your test suite.
If you would like to re-use a seed to re-test a particular execution order, you can set an environment variable of CHOMA_SEED.
> CHOMA_SEED=myseed mocha ./tests/ --require choma