mock.ts

type JestFNs<T> = { [P in keyof T]: jest.MockInstance<any> };
type Mocked<T> = JestFNs<T> & { reset(): void };
export type Mock<T> = T & { mock: Mocked<T> };

export default function mock<T extends any>(
  inst: Partial<T> = {} as any
): Mock<T> {
  const target = {} as any;
  const proxy = new Proxy(target, {
    get(target: any, key: string) {
      if (key === 'then' && !inst[key]) {
        return;
      }

      return (
        target[key] ||
        (target[key] = ['function', 'undefined'].includes(typeof inst[key])
          ? jest.fn(inst[key])
          : inst[key])
      );
    },
  }) as Mock<T>;

  target.mock = proxy;
  target.mock.reset = () =>
    Object.values(target as JestFNs<T>).forEach(
      fn => fn.mockReset && fn.mockReset()
    );

  return proxy;
}