Assert a button with the given text is (or is not) in the administrator toolbar. A button inside the "Actions" dropdown counts; its markup is in the page even while the dropdown is closed.
Examples
Then I should see the "New" toolbar button
Then I should see the "Save & Close" toolbar button
Then we should not see the "Delete" toolbar button
And I should see the "Publish" toolbar button
Then should see the "Options" toolbar button
Pattern
Then(/^(I |we )*should( not)* see the "([^"]*)?" toolbar button$/, …)
Part of @webship-js/joomla-steps (github.com/webship/joomla-steps), a step pack for Webship-js 2.0.x.