t value should be replace');
}, 'Default value');

test(t => {
  const anim = createDiv(t).animate(null);
  anim.effect.composite = 'add';
  assert_equals(anim.effect.composite, 'add',
                'The effect composite value should be replaced');
}, 'Change composite value');

test(t => {
  const anim = createDiv(t).animate({ left: '10px' });

  anim.effect.composite = 'add';
  const keyframes = anim.effect.getKeyframes();
  assert_equals(keyframes[0].composite, 'auto',
                'unspecified keyf