Clear every cache group of the site: open "Maintenance: Clear Cache", press "Delete All" and wait for Joomla's confirmation.
Examples
When I clear all caches
When we clear all caches
And I clear all caches
When clear all caches
And we clear all caches
Pattern
When(/^(I |we )*clear all caches$/, …)
Part of @webship-js/joomla-steps (github.com/webship/joomla-steps), a step pack for Webship-js 2.0.x.