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repobuddy

Check Jest dependencies in CI

A Jest preset names packages, such as transformers and watch plugins, that your project has to install. When one is missing, Jest fails, or it finds a copy that another package pulled in and the next install removes. buddy check-deps exits 1 in that case, so it can stop a build.

check-deps is a command you run. It is not an install hook.

Steps

Section titled “Steps”

  1. Install repobuddy.

    Terminal window
    pnpm add -D repobuddy

  2. Run the check once and install what it reports.

    Terminal window
    pnpm exec buddy check-deps
    missing dependencies: 2 used by jest.config.mjs but not declared in package.json
      jest-esm-transformer-2  preset(@repobuddy/jest/presets/ts) transform
      ts-jest                 preset(@repobuddy/jest/presets/ts) transform
    install: npm i -D jest-esm-transformer-2 ts-jest

    The install line uses the packageManager field of package.json. Add that field to get a pnpm add -D, yarn add -D, or bun add -d line.

  3. Run it again until it prints all declared in package.json. A preset can ask for different packages once others are installed.

  4. Add a script for it in package.json.

    {
      "scripts": {
        "check-deps": "buddy check-deps"
      }
    }

  5. Run the script in CI, before the tests.

    - run: pnpm install --frozen-lockfile
    - run: pnpm check-deps
    - run: pnpm test

  6. In a workspace, check each package that has a Jest config.

    - run: pnpm exec buddy check-deps --cwd packages/app
    - run: pnpm exec buddy check-deps --cwd packages/lib

    A package with no Jest config passes with dependencies: no jest configuration found, nothing to check.

Run it before tests on your machine

Section titled “Run it before tests on your machine”

To run it before every local test run, name it pretest instead of check-deps. npm runs a pretest script before test. Check that your package manager runs pre scripts before you rely on this.

Verify

Section titled “Verify”
  1. Remove a package that the check reported from devDependencies.
  2. Run pnpm check-deps. It lists the package and exits 1.
  3. Put the package back. The check prints all declared in package.json and exits 0.
Section titled “Related”