Assert a field of the form is, or is not, required, read-only or marked as invalid, from the classes Odoo puts on the field (o_required_modifier, o_readonly_modifier, o_field_invalid).
Examples
Then the "Customer" field should be required
And the "Total" field should be read-only
Then the "Customer" field should be invalid
And the "Expiration" field should not be required
Then the "Customer" field should not be read-only
Pattern
Then(/^the "([^"]*)" field should( not)* be (required|read-only|readonly|invalid)$/, …)
Part of @webship-js/odoo-steps (github.com/webship/odoo-steps), a step pack for Webship-js 2.0.x.