Commit hooks

The most common reason for failed tests on CI is when a developer forgets to run the tests locally. Code in a repository can contain bugs, that's a given, but at least it should never have bugs that could be found by tests, so running tests before a commit is a mandatory practice in lots of companies.

Let's follow this best practice. We will use a library called Husky, which can wire to Git hooks to run desired scripts.

We start with packages, as always:

$ npm install husky --save-dev

Next, we need to set scripts in package.json:

// package.json
{
  "scripts": {
    "test": "NODE_ENV=test jest",
    "precommit": "npm test"
  }
}

And this is it; from now on, before any commit, Husky will run your tests. So, there will be fewer surprises after pushes.