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I'd like to set some defaults for mocha without having to type them each time. Does mocha look for a config file / dotfile anywhere, as jshint looks for .jshintrc and npm looks for package.json?

mcandre
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    The accepted answer is now deprecated. I suggest accepting the new one (https://stackoverflow.com/a/54804446/1740079) to prevent more people from using the old approach. – ichigolas Jun 11 '20 at 16:58

3 Answers3

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Yes. You can create a file ./test/mocha.opts and in the file you can specify --no-colors.

See mocha.opts on Mocha Doc for more information.

Christian Esperar
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zs2020
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Mocha recommends mocha --config=.mocharc.json.

There are new formats too, like yaml. See some examples.

Old answer:

The default is ./test/mocha.opts. You can pass a custom path with the --opts parameter :

mocha --opts ./mocha.opts

Useful in case you don’t store your tests in test/ folder, but next to code files, for example.

Any name and extension seems to work, so you can even do mocha --opts .mocharc if you want it to go well with .jshintrc, .babelrc and the like.

gabssnake
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    This is (or at least was), a very obscure function. I had given up hope for such a thing long ago, and thank you for pointing out it's possible now. :) – DBrown Aug 12 '16 at 01:40
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    THANK YOU! Tests should really be next to files. Locality is important! – Byron Whitlock Sep 07 '16 at 17:47
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    Is it possible for the contents of the file to be JSON? – Jared Dykstra Sep 28 '17 at 15:06
  • It doesn’t seem like so. The CLI splits the content by spaces and then parses it with `commander` module. `commander`’s parser expects a string array. `mocha` source: https://github.com/nishigori/mocha/blob/8ba8416981993de3287b14a80b9ee9d11fe647a7/bin/_mocha#L175 - `commander` source: https://github.com/tj/commander.js/blob/d9abf56c43a93e9584e2e18a9f8fb5af552f738c/index.js#L212 – gabssnake Sep 29 '17 at 16:50
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    You could launch `mocha` in a script and pass your JSON file contents. See: https://github.com/mochajs/mocha/wiki/Using-mocha-programmatically#set-options – gabssnake Sep 29 '17 at 16:54
  • strange, I couldnt get `--config ./mocha.opts` to work as per their official docs but `--opts ./mocha.opts` worked... thanks! – andy mccullough Jan 10 '18 at 12:53
  • This will no longer work. See: https://stackoverflow.com/questions/60283197/mocha-opts-deprecated-how-to-migrate-to-package-json – Martin Capodici Feb 25 '22 at 23:53
  • Thanks @MartinCapodici, updated the answer to reflect the newest mocha behavior – gabssnake Feb 27 '22 at 10:15
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In mocha 6+ the mocha.opts was changed to legacy and the new place to define your configuration is a .mocharc file that can have different formats (JSON, YAML, JS) as described in the docs or a JSON config added to the package.json using mocha key.

Specifying your own path to mocha config is done using --config <file> but mocha uses any .mocharc.* file as default in order described in the docs (JS, YAML, YML, JSON) and also automatically uses mocha key from package.json with lower priority than a given config file.

crackmigg
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    An example .mocharc.js file is here: https://github.com/mochajs/mocha/blob/master/example/config/.mocharc.js (and there are other formats in that directory as well). – Peter W Jul 25 '19 at 02:50