Assert the page is, or is not, the portal: the "My Account" area a portal user lands on (/my, rendered inside #wrap.o_portal_wrap).
Examples
Then I should be in the portal
And we should be in the portal
Then we should be in the customer portal
And I should not be in the portal
Then I should not be in the customer portal
Pattern
Then(/^(I |we )*should( not)* be in the (?:customer )?portal$/, …)
Part of @webship-js/odoo-steps (github.com/webship/odoo-steps), a step pack for Webship-js 2.0.x.