Making use of callback values

In this section, we’ll introduce a new state variable, customer, that will be set when CustomerForm receives the onSave callback. After that, we’ll do the final transition in our workflow, from addAppointment back to dayView.

Follow these steps:

1. This time, we’ll check that the new customer ID is passed to AppointmentFormLoader. Remember in the previous section how we gave saveCustomer a customer parameter? We’ll make use of that in this test:

   it("passes the customer to the AppointmentForm", async () => {
     const customer = { id: 123 };
     render(<App />);
     beginAddingCustomerAndAppointment();
     saveCustomer(customer);
     expect(AppointmentFormLoader).toBeRenderedWithProps(
       expect.objectContaining({
         original: expect.objectContaining({
           customer...