Assert the page head advertises the REST API: the <link rel="https://api.w.org/"> that WordPress prints, which clients use to discover the API.
Examples
Then the page should advertise the REST API
And the page should advertise the REST API
But the page should advertise the REST API
Then the page should not advertise the REST API
But the page should not advertise the REST API
Pattern
Then(/^the page should( not)* advertise the REST API$/, …)
Part of @webship-js/wordpress-steps (github.com/webship/wordpress-steps), a step pack for Webship-js 2.0.x.