vant/test/touch-utils.js

// Trigger touch event
export function triggerTouch(wrapper, eventName, x = 0, y = 0) {
  const el = wrapper.element ? wrapper.element : wrapper;
  const touch = {
    identifier: Date.now(),
    target: el,
    pageX: x,
    pageY: y,
    clientX: x,
    clientY: y,
    radiusX: 2.5,
    radiusY: 2.5,
    rotationAngle: 10,
    force: 0.5
  };

  const event = document.createEvent('CustomEvent');
  event.initCustomEvent(eventName, true, true, {});
  event.touches = [touch];
  event.targetTouches = [touch];
  event.changedTouches = [touch];

  el.dispatchEvent(event);
}

// simulate drag gesture
export function triggerDrag(el, x = 0, y = 0) {
  triggerTouch(el, 'touchstart', 0, 0);
  triggerTouch(el, 'touchmove', x / 4, y / 4);
  triggerTouch(el, 'touchmove', x / 3, y / 3);
  triggerTouch(el, 'touchmove', x / 2, y / 2);
  triggerTouch(el, 'touchmove', x, y);
  triggerTouch(el, 'touchend', x, y);
}