testing-error.js

it('should show error UI', async () => {
  const dogMock = {
    request: {
      query: GET_DOG_QUERY,
      variables: { name: 'Buck' },
    },
    error: new Error('aw shucks'),
  };

  const component = renderer.create(
    <MockedProvider mocks={[dogMock]} addTypename={false}>
      <Dog name="Buck" />
    </MockedProvider>,
  );

  await wait(0); // wait for response

  const tree = component.toJSON();
  expect(tree.children).toContain('Error!');
});