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An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Automated Testing

There are many different types of automated testing, which all have separate roles to play. Ideally, automated testing can be run locally as well as part of a continuous integration workflow.

Validating HTML output


HTMLProofer is the most common tool in use for ruby projects at TTS for validating HTML output. It is used in our guides to ensure that internal links are not broken, but it can also be used for a broad range of image, link, and script tests.

HTMLProofer can be run on the command line directly, as a Rake task or as part of a CI action.

Warning: Some government websites are very sensitive to crawlers, and so testing external government links can cause HTMLProofer to fail with an opaque error like 1 No Error. If you are testing external links in a CI/CD pipeline, you may regularly have to manually check errors to ensure that they are valid. When a link is actually broken, HTMLProofer will display a diagnostic message about where the bad link originated.