Function setClientRects

packages/react-dom/src/__tests__/utils/IntersectionMocks.js:82–95

(target, rects)

 * Stub out getClientRects for the specified target.
 */
export function setClientRects(target, rects) {
  target.getClientRects = function () {
    return rects.map(({x, y, width, height}) => ({
      width,
      height,
      left: x,
      right: x + width,
      top: y,
      bottom: y + height,
      x,
      y,
    }));
  };
}