我有另一个选择，也许这看起来更好

test('Should throw if bcrypt throws', async () => {
  const sut = makeSut()
  jest.spyOn(bcrypt, 'hash').mockImplementationOnce(() => {
    throw new Error()
  })
  const promise = sut.encrypt('any_value')
  await expect(promise).rejects.toThrow()
})

这对我很有效：

const hashSpy = jest.spyOn(bcrypt, "hash") as unknown as jest.Mock<
      ReturnType<(key: string) => Promise<string>>,
      Parameters<(key: string) => Promise<string>>
    >;
hashSpy.mockResolvedValueOnce("hashedPassword");

这对我很有效：

const hashSpy = jest.spyOn(bcrypt, 'hash') as unknown as jest.Mock<
ReturnType<(key: Error) => Promise<Error>>,
Parameters<(key: Error) => Promise<Error>>
>
hashSpy.mockReturnValueOnce(new Promise((resolve, reject) => reject(new Error())))

我设法解决了一个类似的问题，把类型在SpyOn：

jest.spyOn<any, string>(bcrypt, "hash")
      .mockReturnValueOnce(
        new Promise((resolve, reject) => reject(new Error()))
      );