Method setMutex

packages/jest-runtime/src/internals/TransformCache.ts:118–120

(key: string, promise: Promise<void>)

    return this.mutex.get(key);
  }
  setMutex(key: string, promise: Promise<void>): void {
    this.mutex.set(key, promise);
  }
  clearMutex(key: string): void {
    this.mutex.delete(key);
  }