Displaying SvelteKit form errors

In this section, we’ll add tests and functionality to support passing in a new form prop into the BirthayForm component.

Let’s start with a new test:

1. In the src/routes/birthdays/BirthdayForm.test.js file, add a new nested describe block with a single test, as shown in the following code snippet. It checks that if the error property is set on the form prop, then that error must be displayed somewhere on the page:

   describe('validation errors', () => {
     it('displays a message', () => {
       render(BirthdayForm, {
         form: {
           error: 'An error'
         }
       });
       expect(
         screen.queryByText('An error')
       ).toBeVisible();
     });
   });

2. Make that...