Assert the logged-in account has, or does not have, a role. The role is its slug: administrator, editor, author, contributor, subscriber, or one a plugin adds.
Examples
Then my account should have the "editor" role
And my account should have the "administrator" role
Then my account should not have the "administrator" role
And my account should not have the "editor" role
Then my account should have the "subscriber" role
Pattern
Then(/^my account should( not)* have the "([^"]*)" role$/, …)
Part of @webship-js/wordpress-steps (github.com/webship/wordpress-steps), a step pack for Webship-js 2.0.x.