An Elixir client for the Nu HTML Checker (v.Nu).

v.Nu is a document validity checker used by the W3C. It offers validating HTML, CSS, and SVG documents.

This library brings that functionality to Elixir by using the Checker's JSON API. It offers ExUnit assertions for validating dynamic content in tests, Mix tasks for validating static content, and general purpose functions to fulfill other needs.

While it is possible to use this library with the service run by W3C at validator.w3.org/nu, I would recommend running your own instance. You will eliminate a lot of network latency if it runs on the same machine as your code, and you will not hit any rate limits that might exist for validator.w3.org/nu.

The source of the Checker can be found in the repository validator/validator. Follow their instructions on how to download it and run it as a web server.

The easiest option is to use the Docker image, like this:

docker run -d --rm -p 8888:8888 ghcr.io/validator/validator:latest

The command might require an additional --platform linux/amd64 flag on M1 macs.

Check if the server is running:

$ curl localhost:8888 -I
HTTP/1.1 200 OK

Make sure to read about the prerequisites first.

Add Vnu as a dependency to your project's mix.exs. To use the built-in, Hackney-based HTTP client adapter, also add :hackney:

defp deps do
  [
    {:vnu, "~> 1.1", only: [:dev, :test], runtime: false},
    {:hackney, "~> 1.18"}
  ]
end

Then run:

$ mix deps.get

If you don't want to use Hackney, you can implement your own HTTP client module using the Vnu.HTTPClient behavior and pass it in the http_client option.

Available on hexdocs.pm.

See the usage guide.

Make sure to read about the prerequisites first.

After cloning the repository, run mix deps.get and you should be ready for development.

To ensure code consistency, run mix lint.

All test that expect to talk with the server accept the server's URL as an VNU_SERVER_URL environment variable or fallback to the default http://localhost:8888.

$ VNU_SERVER_URL=http://localhost:4000/ mix test 

If you're adding a new test, make sure it will do that do.

If you noticed a problem with the library or its documentation, or have an idea for a feature, open an issue.

If you have an idea on how to act upon the problem or idea, feel free to open a pull request instead.

If you noticed a problem with the library or its documentation and know how to fix it, or have an idea for a feature, or want to fix a typo, open a pull request.

If you are not sure of your changes or need help finishing them, open a pull request anyway. I'll try to help!

Vnu is released under the MIT License. See the LICENSE file for further details.