Assert the Smart Search answered with no results: Joomla keeps the results list and prints its "no results were found" sentence (which repeats the term) instead of entries.
Examples
Then I should see no search results
And we should see no search results
Then should see no search results
And I should see no search results
Then we should see no search results
Pattern
Then(/^(I |we )*should see no search results$/, …)
Part of @webship-js/joomla-steps (github.com/webship/joomla-steps), a step pack for Webship-js 2.0.x.