@dotcom-tool-kit/lint-staged NPM

@dotcom-tool-kit/lint-staged

A plugin to run the lint-staged tool to run linters on files staged via git.

Installation

With Tool Kit already set up, install this plugin as a dev dependency:

npm install --save-dev @dotcom-tool-kit/lint-staged

And add it to your repo's .toolkitrc.yml:

plugins:
    - '@dotcom-tool-kit/lint-staged'

How LintStaged interacts with other hooks

The LintStaged is quite special as it's a task that will run other Tool Kit hooks. That means you can have a hook that will run this task that will in turn run other hooks that will run further tasks! The indirection can be hard to get your head around. Typically, you'll want to set up LintStaged to run on a Tool Kit hook hooked to a git hook via another plugin like husky-npm (LintStaged by default runs on the git:precommit hook). Then it will call the lint-staged executable that will read your lint-staged configuration to see what further programs need to be run: these programs should be other Tool Kit hooks that can be configured using a plugin like lint-staged-npm.

An example package.json config set up with lint-staged and Tool Kit could have these fields:

{
  "husky": {
    "hooks": {
      "pre-commit": "dotcom-tool-kit git:precommit"
    }
  },
  "lint-staged": {
    "**/*.js": "dotcom-tool-kit format:staged test:staged --"
  }
}

This will run the git:precommit hook when making a git commit, and the LintStaged task in git:precommit will run the lint-staged binary, which will pass all the staged JavaScript files to a Tool Kit invocation that will call the format:staged and test:staged hooks (see the lint-staged-npm README for further information on what we do with the passed files). This control flow is illustrated in the following diagram:

flowchart
    A[git commit] --> B[husky pre-commit hook] --> h1
    subgraph h1[git:precommit hook]
    C[dotcom-tool-kit git:precommit] --> D[LintStaged]
    end
    D --> E[lint-staged] --> h2
    subgraph h2[format:staged hook]
    F[dotcom-tool-kit format:staged -- index.js] --> G[Prettier]
    end
    G --> H[prettier index.js]