locha

Loud Mocha (locha) runs specs twice - first time runs all tests, then the second time just the failing ones with extra environment variables

Demo

File demo/failing-spec.js has two specs, one of which is failing. The specs also will produce a lot of log messages if running with DEBUG=failing ... flag. By default we do NOT want to see the debug log messages, but we do need these messages to debug a failing test. Usually if CI fails, we would rerun the failing test locally with DEBUG=failing ..., but why can't CI do this for us automatically?

• Run all tests with minimal verbosity. Most of the tests (if not all!) pass.
• If any tests failed during the first run, rerun just these failing tests with extra environment variables. For example we can turn on verbose logging.

The demo below shows locha in action. First round has all the tests with just a few console.log statements. Second round of testing is triggered because test "failing spec B" fails, and is rerun with {"DEBUG":"failing"} additional environment variable set, which produces a lot more output.

$ npm run demo
> ./bin/locha.js demo/failing-spec.js --env DEBUG:failing

  failing spec
in "failing spec A"
    ✓ A
in "failing spec B"
    1) B

  1 passing (14ms)
  1 failing

  1) failing spec B:
     Error: B fails
      at Context.<anonymous> (demo/failing-spec.js:22:11)

mocha finished with 1 failure
Failed first time, rerunning 1 test

  failing spec
in "failing spec B"
  failing a lot of +0ms
  failing verbose +1ms
  failing messages +1ms
  failing in debug +0ms
  failing mode in test B +0ms
    1) B

  0 passing (5ms)
  1 failing

  1) failing spec B:
     Error: B fails
      at Context.<anonymous> (demo/failing-spec.js:22:11)
mocha finished with 1 failure

The verbose second run makes debugging just the failing tests simple and quick. I picked environment variables to control verbosity because to me command line switches control what to do, and environment variables control how to do it. Extra logging seems a good "how to do it" kind of thing.

Install

Requires Node version 6 or above.

npm install --save-dev locha

Use

Pass additional environment variables using --env string, and specs as a list of files. For example if we want to set DEBUG=my-module MODE=test ... during the second run with just failing tests, the test command would be

{
    "scripts": {
        "test": "locha --env 'DEBUG:my-module,MODE:test' test/*-spec.js"
    },
    "devDependencies": {
        "locha": "1.0.0"
    }
}

Debugging

To see verbose log messages, run with DEBUG=locha environment variable

Examples

• CoffeeScript tests
• recursive tests
• custom reporters

Mocha options

Mocha supports a LOT of command line options. Locha only supports some of them. Here they are

-t, --timeout <ms>
-r, --require <module name>
-R, --reporter <reporter name>
-O, --reporter-options <k=v,k2=v2,...>
--compilers <ext1>:<module name1>,<ext2>:<module name2>
--opts <filename>
--recursive

Related projects

• focha - Mocha wrapper that runs previously failed tests first
• rocha - Runs Mocha unit tests but randomizes their order
• snap-shot-it - Smarter snapshot utility for Mocha and BDD test runners

Small print

Author: Gleb Bahmutov <[email protected]> © 2017

• @bahmutov
• glebbahmutov.com
• blog

License: MIT - do anything with the code, but don't blame me if it does not work.

Support: if you find any problems with this module, email / tweet / open issue on Github

MIT License

Copyright (c) 2017 Gleb Bahmutov <[email protected]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.