As a merchant,
When I visit my merchant's invoices index (/merchants/merchant_id/invoices)
Then I see all of the invoices that include at least one of my merchant's items
And for each invoice I see its id
And each id links to the merchant invoice show page
As a merchant, When I visit my merchant's invoices index (/merchants/merchant_id/invoices) Then I see all of the invoices that include at least one of my merchant's items And for each invoice I see its id And each id links to the merchant invoice show page