A Jekyll plugin to test frontmatter on posts and other documents in a Jekyll site.

Jekyll Frontmatter Tests

A gem to add tests to your Jekyll site to make sure you're always including required fields on posts or other collection documents.


  1. For now, create a directory at deploy/tests/schema in the root of your jekyll site. This command should do the trick: mkdir -p deploy/tests/schema.

    Eventually the plugin will load the location of these schema files from _config.yml but for now, the plugin will expect that directory to exist.

  2. Create a YAML file in the directory you just created called _posts.yml. Add a new line for each required field. If, for example, your site requires posts to have a title and authors keys, your schema file would look like this:

    title: "String"
    authors: "String"

    The part on the other side of the colon is what "type" of thing we expect the field to be. Right now we only really support "String" and "Array". In that same example, if you're authors section in the post looks like this:

    title: "Title of the post"
    - jane
    - jim

    You want your schema to look like this:

    title: "String"
    authors: "Array"

    If you have an attribute set to Array, you can optionally provide more complex validation. What the following indicates is that we want tags to be an array, that has only the tags trees and/or bushes, without dashes or uppercase characters.

      type: Array
      one_of: ['trees', 'bushes']
      rules: [no-dash, lowercase]

    There is an example.yml file in this repo to give you a sense of how to structure the file.

    Eventually we want to support the following types:

    • String
    • Array
    • Date strings
    • Integers
    • Complex array validation
  3. At the end of each schema file, add a config section that looks like this:

      path: '_posts'
      - ..
      - .
      - .DS_Store
      optional: ['layout', 'date']

    This section contains some information that the test runner uses to know some things about your environment.

    Required in this section:

    • The path variable is used to point to the collection documents.
    • The ignore section can be used to exclude certain files in the collection directory from testing. If you're okay with this document not passing tests, add it to the ignore list.


    • optional is used to point out frontmatter fields that a document might have but isn't required.

    Right now we don't do anything with optional but a future version might allow you to pass a flag to include these fields. This could be useful if you expect these fields to be in a specific format.


-a - The default, checks all collections with a schema document at /deploy/tests/schema -c COLLECTION - Target a specific collection, for example jekyll test -c albums would test any documents in the "albums" collection against a defined schema. -p - Test only posts.

Again, by default jekyll test runs with -a, the flag is there if you want to be explicit. The other flags are useful if you have a site with many collections and many documents inside them. for example has hundreds of _posts and _team documents, running -c team generates cleaner results if we're only interested in our "team" documents.


@gboone wrote most of the code in here so it probably stinks!

  • If it's a bug and you don't want to get messy with Ruby, file an issue!
  • If it's a bug you already fixed, fork the repo and open a pull request!
  • If you're using it in the wild, file an issue and let us know!

See our file for more on how to get involved.