Adding a Playwright test for validating form errors

In this section we’ll write another Playwright test and then do some up-front planning for the Vitest unit tests we’ll need.

Here’s the next end-to-end test, which you can now add to tests/birthdays.test.js. It fills in the birthday form, just as in the previous chapter, but this time, the Date of birth field value is invalid: it is, literally, the word invalid, which is not a valid date of birth:

test('does not save a birthday if there are validation errors', async ({
  page
}) => {
  await page.goto('/birthdays');
  await page.getByLabel('Name').fill('Demeter');
  await page
    .getByLabel('Date of birth')
    .fill('invalid');
  await page.getByRole('button').click();
  await expect(
    page.getByText('Demeter...