A GitHub action that checks pull requests description and contents

This GitHub action checks for the presence/absence of a string or group of strings in the body or diff, as well as certain conditions in the PR: number of files changed, and number of lines changed.

It uses the GitHub API, so you'll need to provide a token. Don't worry, that's built-in.

Using this action

You would need to put this in a YAML file in the .github/workflows directory

name: "Check PR content"
on: [pull_request]

jobs:
  check_pr:
    runs-on: ubuntu-latest
    steps:
    - name: Check PR
      uses: JJ/github-pr-contains-action@releases/v14.1
      with:
        github-token: ${{github.token}}
        bodyDoesNotContain: "Delete|this"
        bodyContains: 'Test'
        diffContains: ';'
        diffDoesNotContain: "TODO|to do"
        filesChanged: 1
        linesChanged: 1
        waivedUsers: "SomeOne|dependabot[bot]"

The bodyContains variable will include the string that we want the body of the PR to include, such as checked items in a checklist; obviously bodyDoesNotContain will hold the opposite, what we don't want to see in the PR body. Any of them can have a | separated list of words or expressions. The PR will check it contains any of the words in bodyContains and none of the words in bodyDoesNotContain.

Same pattern for diff(Contains|DoesNotContain). Can be a word or list of words you want in the diff (for instance, you want it to always change code so it contains a statement terminator) or don't want in the diff (for instance, you don't want it to include TODOs because people never ever do them). If you want to allow check marks, remember to use an expression such as [x]|[X], since both are admissible as such in a body.

These strings are unwittingly converted into regular expressions, so any regular expression will also work; []()+?* are escaped so that things such as [.] work with the literal meaning. They can be left empty if you don't need that specific check. This also implies that all these regex marks will not be used as such, so avoid using things such as [xX] to indicate alternatives.

Finally, waivedUsers is a |-separated string of the users that will be spared from running these checks; if the PR is triggered by one of those users, it will exit with a warning and with a green status. By default, it has the value "dependabot[bot]". If you want to edit more and want to keep dependabot PRs from failing, add it to your list.

An example is used as .github/workflows/check-PRs-here.yaml in this repository as well as this one, which is the one I use for testing.

You might want to qualify possible events that trigger this action, for intance, this way:

  pull_request:
    types:
      [opened, edited, assigned, closed, synchronize, review_requested, ready_for_review]

This will skip diff checks every single push, for instance. Please remember that this action will only work in pull requests, since it checks the pull request object payload. It will simply skip any check (with a warning) if it is not triggered by a pull_request or pull_request_target event.

For instance, you might want to use a GitHub action such as this one for the CONTRIBUTORS.md file:

name: "Check contributors file additions"
on:
  pull_request:
    types: [opened, edited]
    paths:
      - CONTRIBUTORS.md

jobs:
  check_pr:
    name: "Checks contributors"
    runs-on: ubuntu-latest
    steps:
      - name: Check that any new contributor links to their github page
        uses: JJ/github-pr-contains-action@releases/v14.1
        with:
          github-token: ${{github.token}}
          linesChanged: 1
          filesChanged: 1
          diffContains: "github.com/"
          waivedUsers: "dependabot[bot]|CompanyBigWig"

It would check that there's only a single file modified (because why would you need to change another, if all you want is to add your name to the contributors' file), a single line is changed (because you're only one, right?) and that it includes a link to your GitHub profile by forcing the diff to contain that string. It would also allow the company's big wig to add however many they want, with or without links to their profiles.

Working with action outputs

This action produces two outputs: diff, containing effectively the diff included in the PR, and numberOfFiles, with the list of files that have been included in the PR. You can use that, for instance, this way:

      - name: Info PR
        env:
          NUMBER_OF_FILES : ${{ steps.dev_check_pr.outputs.numberOfFiles }}
        run: |
          echo "::warning::We got files: $NUMBER_OF_FILES"
      - name: Fail if too big
        if: ${{ steps.dev_check_pr.outputs.numberOfFiles > 3 }}
        env:
          NUMBER_OF_FILES : ${{ steps.dev_check_pr.outputs.numberOfFiles }}
        run: |
          echo "::error::Too many files, there are $NUMBER_OF_FILES, should be at most 3"
          exit 1

to show the number of files present in the PR, as well as to fail if there are too many files (to enforce keeping PRs small, for instance).

The diff output might contain a huge amount of information, which might make it a bit hard to deal with via environment variables. Dealing with it otherwise, via github-script, is probably fine.

Contributing to development

Any suggestion, bug report, etc, is appreciated. Please check out or create an issue before contributing a PR, if possible.

Developing and testing

GitHub actions are notoriously hard to test in any other way than actually running them, so this repository is set up for local tests in a dev branch; create that branch and work with it until you're satisfied and merge it to main.

I write this as much for myself as for any other purpose...

See also

There are several forks of this action, with additional features:

• PR content checker by @jsoares
• Francisco Giordano's pr-content-checker
• Pablo Statsig's pr-content-checker

History

Tags for every release are preceded by releases/

• v0: proof of concept, published to marketplace
• v1: Adds several more checks
• v2: Adds check for strings to avoid and creates issues for errors.
• v3: Changes packaging, upgrades modules, deletes unneeded files.
• v4: Solves a number of issues.
• v5: Will not use diffContains if it's an empty string
• v6: can use words or regular expressions in bodyContains/ bodyDoesNotContain
• v7: includes more "rexified" characters: *,?,+
• v8: adds diffDoesNotContain and extends regex testing to diff tests.
• v9: adds some informative messages, disables API calls for private repositories.
• v10: Skips checks if not in a pull request; adds information to prevent this use too.
• v11: Adds a configuration variable that skips users, with dependabot skipped by default (or passed through).
• v12: Make it compatible with private repos. Upgrade to latest github API.
• v13: Fixes the use of waivedUsers which didn't actually work.
• v14: Eliminates setting of environment variables, documents using action output.
• v14.1: Refrains from doing diff stuff if no variable related to diff has been set

License

(c) JJ Merelo, 2021-2014. Released under the MIT license. Read LICENSE for more details.