test.js

suite('Setting "opened" as true', () => {
  const sut = fixture('someId');

  suiteSetup(() => {
    sut.opened = true;
  });
    
  test('opens the modal', () => {
    assert.isTrue(isVisible(sut));
  });
    
  test('"aria-hidden" attribute is set to false', () => {
    assert.equal(sut.getAttribute('aria-hidden'), 'false');
  });
});