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Last updated: 27 May 2022

govuk_publishing_components: # Auditing


The component guide includes some auditing of components and applications that can provide useful information. It can be found at /component-guide/audit.

It is designed to be run locally as it gets information about applications and how they use components from local files. If your local copy of an application is not up to date the information reported by the auditing may be incorrect.


The aim of the auditing is to provide information about our components and how they are used in frontend applications on GOV.UK. This includes warnings about possible problems with how we are using our component individual asset model. This includes:

  • where an application is using a component but has not included required assets
  • where an application is not using a component but has included unneeded assets

In some cases an application may use a component but not include its assets. This is usually because the assets are already included globally in static. For example, at time of writing the action link component is being used in collections and also in the site header, so the Sass for the component is included only in static, to prevent duplication. The auditing checks this and suppresses any warnings for missing assets in applications where they are already included in static.

The auditing also includes other warnings, such as:

  • where applications contain jQuery
  • where applications are overriding component styles
  • where applications are using components that don't exist

How it works

The auditing has three main areas. Depending on where the component guide is being run, some of this information will not be available.

  1. component information (determined from the gem, always available)
  2. how the current application is using components (if viewing the component guide inside an application)
  3. how all applications are using components (if viewing the component guide running locally in standalone mode, alongside the code for the other applications)

All information is determined by the auditing code performing regular expression matches on files that it can access. This means that when the auditing is running locally it is only as up to date as the repositories on your machine. This also means it can be quite slow to load, as it's doing a lot of things.

The auditing knows what to show based on two values - @in_application and @other_applications. They determine whether the auditing page includes the tab for 'Applications', and whether the 'Components by application' section of the 'Components' tab is shown.

Remote/local application Gem running remotely Gem running locally
@in_application true false false
@other_applications false false true
Applications tab Shows info for this app Not shown Shows info for all apps
Components by application Not shown Not shown Shown

Note that the combination of true/true for both @in_application and @other_applications shouldn't be possible - if the gem is inside an application, it can't access other applications.