Follow a submenu entry of the admin menu: the menu is opened by pointing at its top-level entry, as a user does.
Examples
When I click "Permalinks" under "Settings" in the admin menu
When we click "Categories" under "Posts" in the admin menu
And I click "Site Health" under "Tools" in the admin menu
When I click "Add Post" under "Posts" in the admin menu
And we click "Profile" under "Users" in the admin menu
Pattern
When(/^(I |we )*click "([^"]*)" under "([^"]*)" in the admin menu$/, …)
Part of @webship-js/wordpress-steps (github.com/webship/wordpress-steps), a step pack for Webship-js 2.0.x.