GitHub Prettier Action

A GitHub action for styling files with prettier.

Usage

Parameters

Parameter	Required	Default	Description
dry	❌	false	Runs the action in dry mode. Files wont get changed and the action fails if there are unprettified files. Recommended to use with prettier_options --check
no_commit	❌	false	Can be used to avoid committing the changes (useful when another workflow step commits after this one anyways; can be combined with dry mode)
prettier_version	❌	latest	Specific prettier version (by default use latest)
working_directory	❌	${{ github.action_path }}	Specify a directory to cd into before installing prettier and running it, use relative file path to the repository root for example app/
prettier_options	❌	"--write **/*.js"	Prettier options (by default it applies to the whole repository)
commit_options	❌	-	Custom git commit options
push_options	❌	-	Custom git push options
same_commit	❌	false	Update the current commit instead of creating a new one, created by Joren Broekema, this command works only with the checkout action set to fetch depth '0' (see example 2)
commit_message	❌	"Prettified Code!"	Custom git commit message, will be ignored if used with same_commit
commit_description	❌	-	Custom git extended commit message, will be ignored if used with same_commit
file_pattern	❌	*	Custom git add file pattern, can't be used with only_changed!
prettier_plugins	❌	-	Install Prettier plugins, i.e. "@prettier/plugin-php" "@prettier/plugin-other". Must be wrapped in quotes since @ is a reserved character in YAML.
clean_node_folder	❌	true	Delete the node_modules folder before committing
only_changed	❌	false	Only prettify changed files, can't be used with file_pattern! This command works only with the checkout action set to fetch depth '0' (see example 2)
github_token	❌	${{ github.token }}	The default GITHUB_TOKEN or a Personal Access Token
git_identity	❌	actions	Set to author to use author's user as committer. This allows triggering further workflow runs
allow_other_plugins	❌	false	Allow other plugins to be installed (prevents the @prettier-XYZ regex check)

Note: using the same_commit option may lead to problems if other actions are relying on the commit being the same before and after the prettier action has ran. Keep this in mind.

Example Config

Hint: if you still use the old naming convention or generally a different branch name, please replace the main in the following configurations.

Example 1 (run on push in branch main)

name: Continuous Integration

# This action works with pull requests and pushes
on:
  pull_request:
  push:
    branches:
      - main

jobs:
  prettier:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Prettify code
        uses: creyD/prettier_action@v4.6
        with:
          # This part is also where you can pass other options, for example:
          prettier_options: --write **/*.{js,md}

Example 2 (using the only_changed or same_commit option on PR)

name: Continuous Integration

on:
  pull_request:
    branches: [main]

jobs:
  prettier:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          # Make sure the actual branch is checked out when running on pull requests
          ref: ${{ github.head_ref }}
          # This is important to fetch the changes to the previous commit
          fetch-depth: 0

      - name: Prettify code
        uses: creyD/prettier_action@v4.6
        with:
          # This part is also where you can pass other options, for example:
          prettier_options: --write **/*.{js,md}
          only_changed: True

Example 3 (using a custom access token on PR)

name: Continuous Integration

on:
  pull_request:
    branches: [main]

jobs:
  prettier:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          ref: ${{ github.head_ref }}
          # Make sure the value of GITHUB_TOKEN will not be persisted in repo's config
          persist-credentials: false

      - name: Prettify code
        uses: creyD/prettier_action@v4.6
        with:
          prettier_options: --write **/*.{js,md}
          only_changed: True
          # Set your custom token
          github_token: ${{ secrets.PERSONAL_GITHUB_TOKEN }}

Example 4 (dry run)

name: Continuous Integration

on:
  pull_request:
    branches: [main]

jobs:
  prettier:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          ref: ${{ github.head_ref }}
          # Make sure the value of GITHUB_TOKEN will not be persisted in repo's config
          persist-credentials: false

      - name: Prettify code
        uses: creyD/prettier_action@v4.6
        with:
          dry: True
          github_token: ${{ secrets.PERSONAL_GITHUB_TOKEN }}

More documentation for writing a workflow can be found here.

Testing

This project includes comprehensive test coverage using BATS (Bash Automated Testing System).

Running Tests Locally

To run the tests locally, execute the test runner script:

./tests/run_tests.sh

This script will automatically:

1. Install BATS and required dependencies if not already present
2. Run all unit tests
3. Run plugin validation tests
4. Run integration tests

Test Structure

The test suite is organized into three main categories:

• tests/unit_tests.bats - Unit tests for bash functions in entrypoint.sh

  • Tests for _git_setup() function with different identity configurations
  • Tests for _git_changed() function for detecting file changes

• tests/plugin_validation_tests.bats - Tests for Prettier plugin validation logic

  • Validates official @prettier/plugin-* format
  • Validates community prettier-plugin-* format
  • Validates scoped @scope/prettier-plugin-* format
  • Ensures invalid plugin names are rejected

• tests/integration_tests.bats - Integration tests for end-to-end workflows

  • Tests working directory handling
  • Tests node_modules cleanup
  • Tests package-lock.json restoration
  • Tests file filtering for only_changed mode
  • Tests dry run behavior

Manual BATS Installation

If you prefer to install BATS manually:

cd tests
./run_tests.sh --install-only

Then run individual test files:

./tests/bats/bin/bats tests/unit_tests.bats
./tests/bats/bin/bats tests/plugin_validation_tests.bats
./tests/bats/bin/bats tests/integration_tests.bats

Continuous Integration

Tests are automatically run on every push and pull request via GitHub Actions. See .github/workflows/test.yml for the CI configuration.

The CI workflow includes:

• Unit tests
• Plugin validation tests
• Integration tests
• End-to-end action testing in dry mode
• ShellCheck linting for bash scripts

Issues

Please report all bugs and feature request using the GitHub issues function. Thanks!

Problem with NPM v9 (19.02.2023)

This issue was discussed in https://github.com/creyD/prettier_action/issues/113. The action until release 4 uses the npm bin command, which apparently doesn't work on npm v9. A fix is introduced with v4.3 of this action. If you need an older version of the action working it works until v3.3 and between v3.3 and v4.2 you could use the workaround described in https://github.com/creyD/prettier_action/issues/113 by adding the below to your workflow file:

- name: Install npm v8
  run: npm i -g npm@8

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