Switch to a vertical tab of a form by its title ("Promotion options", "Authoring information", "Menu settings" on the node form of a theme that renders them as tabs), so the fields behind it become visible.
Examples
When I open the "Promotion options" vertical tab
And I open the "Authoring information" vertical tab
When we open the "Menu settings" vertical tab
And I open the "URL alias" vertical tab
When I open the "Revision information" vertical tab
Pattern
When(/^(I |we )*open the "([^"]*)" vertical tab$/, …)
Part of @webship-js/drupal-core-steps (github.com/webship/drupal-core-steps), a step pack for Webship-js 2.0.x.