react-native-reanimated/src/jestUtils/common.ts

More powerful alternative to Animated library for React Native.

'use strict';

import type { WorkletFunction } from 'react-native-worklets';

/**
 * Converts any callback function to a mock worklet function for testing
 * purposes. This function simulates a worklet by adding the required internal
 * properties.
 *
 * @param callback - Optional callback function to wrap as a worklet. If not
 *   provided, returns an empty worklet.
 * @returns A mock worklet function with the required worklet properties.
 */
export const worklet = <Args extends unknown[] = [], ReturnValue = void>(
  callback?: (...args: Args) => ReturnValue
): WorkletFunction<Args, ReturnValue> => {
  const fn = (callback ?? (() => undefined)) as WorkletFunction<
    Args,
    ReturnValue
  >;
  fn.__workletHash = Math.random();
  return fn;
};

/** Creates a new worklet with the same hash and closure as the original. */
export const cloneWorklet = <Args extends unknown[] = [], ReturnValue = void>(
  original: WorkletFunction<Args, ReturnValue>
): WorkletFunction<Args, ReturnValue> => {
  const w = worklet<Args, ReturnValue>();
  w.__workletHash = original.__workletHash;
  if (original.__closure !== undefined) {
    w.__closure = [...original.__closure];
  }
  return w;
};