svetle-jest-playground/tests/test.app.js

import App from '../src/App.svelte'
import { render, cleanup } from '@testing-library/svelte'
beforeEach(cleanup)
describe('App', () => {
  test('should render greeting', () => {
    const { getByText } = render(App, { props: {name: "world"}})
    expect(getByText('Hello world!'))
  })

  test('two plus two', () => {
    const value = 2 + 2;
    expect(value).toBeGreaterThan(3);
    expect(value).toBeGreaterThanOrEqual(3.5);
    expect(value).toBeLessThan(5);
    expect(value).toBeLessThanOrEqual(4.5);

    // toBe and toEqual are equivalent for numbers
    expect(value).toBe(4);
    expect(value).toEqual(4);
  })

  test('should change button text after click', async () => {
    const { getByText } = render(App, { props: { name: 'world' } })
    expect(getByText('Hello world!'))

    fireEvent.click(getByText('Clicked 0 times'))

    const button = await waitForElement(() => getByText('Clicked 1 times'))

    expect(button).toBeInTheDocument()
  })

})