Submit the backend login form with explicit credentials. Unlike the registry step above, this one does not fail when the login is refused, so it is the step for a scenario about a wrong password. Use the registry step for every other scenario.
Examples
When I log in to the backend as "admin" with password "wrong"
When we log in to the backend as "nobody" with password "secret"
And I log in to the backend as "editor" with password "wrong"
When I sign in to the backend as "admin" with password "wrong"
When log in to the backend as "admin" with password "wrong"
Pattern
When(/^(I |we )*(?:log in|sign in) to the backend as "([^"]*)?" with password "([^"]*)?"$/, …)
Part of @webship-js/typo3-steps (github.com/webship/typo3-steps), a step pack for Webship-js 2.0.x.