watchman-make: focus on your code

One of my favourite software development tools is watchman-make. From its homepage:

watchman-make is a convenience tool to help automatically invoke your build tool in response to files changing. It is useful to automate building assets or running tests as you save files during development.

In short: you change your files, and watchman-make runs the command of your choice. I don’t like to switch away from my IDE as I code, so automatically re-running my test commands helps me stay productive and focused. It’s also extremely easy to configure.

Here are some examples of how I use watchman-make.

  • Automatically run JS tests when a JS source file, test, or fixture template changes (aliased to watchjs)
    watchman-make -p \
      --'js/**/*.js' 'test/**/*.js' 'test/**/*.tmpl' \
      --make 'npm run -s' \
      -t 'changed-files-test'
  • Automatically sync CSS changes to my development server (aliased to watchcss)
    watchman-make -p '**/*.css' --make work -t sync

    (work sync is an inhouse sync command at Box)

  • Run a designated phpunit test file when I change a PHP file (aliased to watchphpunit)
    watchman-make -p '**/*.php' --make ./phpunit -t $@

One shortcoming: watchman-make expects the commands it runs to have a target, eg make install or npm test; it errors if you just set a make parameter and no target parameter, eg ./run_all_my_tests. Fortunately you can bypass this by setting the target parameter to '' (the empty string). (If you’re feeling motivated, I filed an issue about this on the project’s GitHub and the maintainers said they’d be amenable to a PR)

Installation instructions for watchman-make are available on the project’s GitHub. Happy coding!

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