Save the edit form with its main button, whatever it reads: "Save", "Create entry", "Save draft". The step works on the slide-out editor when one is open, else on the page, and waits for the result. Assert the result with the next step: a notification, or the errors of the form.
Examples
When I save the edit form
When we save the edit form
And I save the edit form
And we save the edit form
Then I save the edit form
Pattern
When(/^(I |we )*save the edit form$/, …)
Part of @webship-js/craft-cms-steps (github.com/webship/craft-cms-steps), a step pack for Webship-js 2.0.x.