Confirm the section form open in the off-canvas dialog ("Add section" for a new section, "Update" for an existing one), and wait for the dialog to close.
Examples
When I save the section
And I save the section
When we save the section
And we save the section
When I confirm the section
Pattern
When(/^(I |we )*(?:save|confirm) the section$/, …)
Part of @webship-js/drupal-core-steps (github.com/webship/drupal-core-steps), a step pack for Webship-js 2.0.x.