Assert the WordPress cron endpoint, wp-cron.php, answers without error. It runs the scheduled events that are due, so a fatal error in a plugin's event shows here. A site that runs cron from the system still answers.
Examples
Then the cron should respond
And the cron should respond
Then the scheduled tasks should respond
And the cron should respond
Then the cron should respond without errors
Pattern
Then(/^the (?:scheduled tasks|cron) should respond(?: without errors)?$/, …)
Part of @webship-js/wordpress-steps (github.com/webship/wordpress-steps), a step pack for Webship-js 2.0.x.