Best Practices

IonApp is required for test templates

In your test template when rendering with React Testing Library, you must wrap your component with an IonApp component. This is required for the component to be rendered correctly.

Example.test.tsx

import { IonApp } from '@ionic/react';
import { render } from "@testing-library/react";

import Example from './Example';

test('example', () => {
  render(
    <IonApp>
      <Example />
    </IonApp>
  );
  ...
});

Use user-event for user interactions

React Testing Library recommends using the user-event library for simulating user interactions. This library provides a more realistic simulation of user interactions than the fireEvent function provided by React Testing Library.

Example.test.tsx

import { IonApp } from '@ionic/react';
import { render } from '@testing-library/react';
import userEvent from '@testing-library/user-event';

import Example from './Example';

test('example', async () => {
  const user = userEvent.setup();

  render(
    <IonApp>
      <Example />
    </IonApp>
  );

  await user.click(screen.getByRole('button', { name: /click me!/i }));
});

For more information on user-event, see the user-event documentation.

Import componentOnReady for standalone projects

When testing Ionic components, use the exported componentOnReady helper from @ionic/core instead of calling el.componentOnReady() directly. The helper works with both lazy-loaded and custom-element builds, making it more likely the component has finished rendering before making assertions against its rendered DOM or running accessibility tests.