Javascript Jest mockedCoeus.mockedImplementation抛出一个TypeError

我正在使用Jest编写一个测试并模拟一个调用HTTP请求的函数

import { mocked } from "ts-jest/utils";
import * as pull from "../src/pull";
import fs = require("fs");

// read the reponse data from a file.
const response = JSON.parse(
  fs.readFileSync("./__fixtures__/pr.json", "utf8")
);

// have jest mock the function and set it's response.
jest.mock("../src/pull");
const mockedCoeus = mocked(pull.getPullRequest, true);

mockedCoeus.mockImplementation(async () => {
  return response as any;
});

// write the test.
describe("#get details for a PR", () => {
  it("should load user data", async () => {
    const data = await pull.getPullRequest(165, "data-ios");
    expect(data).toBeDefined();
    expect(data.updated_at).toEqual("2020-04-10T16:46:30Z");
  });
});

但是，测试通过了，当运行

npmjest

TypeError: mockedCoeus.mockImplementation is not a function

我已经查看了其他报告的错误，这些错误与

jest.mock

的位置有关，但是，这里的情况似乎不是这样。为什么会抛出此错误，但测试通过了？我怎样才能修好它