Function mockIsIntersecting

src/test-utils.ts:253–268

(
  element: Element,
  isIntersecting: boolean | number,
)

 * @param isIntersecting {boolean | number}
 */
export function mockIsIntersecting(
  element: Element,
  isIntersecting: boolean | number,
) {
  warnOnMissingSetup();
  const observer = intersectionMockInstance(element);
  if (!observer) {
    throw new Error(
      "No IntersectionObserver instance found for element. Is it still mounted in the DOM?",
    );
  }
  const item = observers.get(observer);
  if (item) {
    triggerIntersection([element], isIntersecting, observer, item);
  }
}

/**
 * Call the `intersectionMockInstance` method with an element, to get the (mocked)