Question

我无法检查承诺在Jest测试中是否拒绝错误。

（发布Jest 20版本:)

  test("Rejects on error", () => {
    expect.assertions(1);
    return expect(promiseHttpsGet(null)).rejects.toBeInstanceOf(Error);
  });

（前Jest 20版）

  test("Rejects on error", () => {
    expect.assertions(1);
    return promiseHttpsGet(null).catch((err) => {
      expect(err).toBeInstanceOf(Error);
    });
  });

我尝试了两个版本，但Jest测试失败了：

Expected value to be an instance of:
  "Error"
Received:
  [Error: connect ECONNREFUSED 127.0.0.1:443]
Constructor:
  "Error"

承诺返回功能是：

function promiseHttpsGet(url) {
  return new Promise((resolve, reject) => {
    https
      .get(url, (response) => {
        let responseBody = "";
        if (response.statusCode !== 200) {
          reject(response.statusCode);
        }
        response.setEncoding = "utf8";
        response.on("data", (data) => {
          responseBody += data;
        });
        response.on("end", () => {
          resolve(responseBody);
        });
      })
      .on("error", (error) => {
        reject(error);
      });
  });
}

任何线索如何解决？感谢。

Answer 1

从Jest 23开始，toThrow匹配器可用于承诺返回功能。

  test("Rejects on error", () => {
    expect.assertions(1);
    return expect(promiseHttpsGet(null)).rejects.toThrow(Error);
  });

或async / await版本：

  test("Throws on error", async () => {
    expect.assertions(1);
    await expect(promiseHttpsGet(null)).rejects.toThrow(Error);
  });

Jest测试.toBeInstanceOf（错误）失败

1 个答案: