如何在 node.js 服务器中使用开玩笑解决未处理的承诺拒绝警告

Question

我的测试正确通过，但我不断收到UnhandledPromiseRejectionWarning。关于如何解决这个问题的任何想法？ 我已经尝试了许多解决方案，但似乎都没有奏效。

node:32535) UnhandledPromiseRejectionWarning: Error: expect(received).toMatchObject(expected)
Matcher error: received value must be a non-null object
Received has value: undefined (node:32535) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:32535) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

这是我的测试文件：

jest.mock("./http");
const { fetchAllUsersData } = require("./http");
test("Data returned from server should be a list of users ", async () => {
fetchAllUsersData()
.catch((errorMessage) => expect(errorMessage).toThrowError(Error))
.then((usersRetrieved) => {
let users = usersRetrieved[0];
let userModel = {
id: 1,
first_name: "Peggy",
last_name: "Poppins",
email: "[e-mail]",
ip_address: "192.54.212.191",
latitude: 34.003135,
longitude: -117.7228641222,
};
expect(users).toMatchObject(userModel);
});
});

这是我在模拟文件夹中的文件：

const fetchAllUsersData = () => {
return Promise.resolve({
data: [
{
id: 1,
first_name: "Merry",
last_name: "Poppins",
email: "[e-mail]",
ip_address: "192.54.212.191",
latitude: 34.003135,
longitude: -117.7228641,
},
{
id: 15,
first_name: "George",
last_name: "Foreman",
email: "[e-mail]",
ip_address: "12.564.124.521",
latitude: 23.592254,
longitude: 125.454227,
},
],
});
};
exports.fetchAllUsersData = fetchAllUsersData;

Answer 1

此错误的原因是承诺未链接以从测试中返回。浮动承诺是一种反模式。async..await允许以比原始承诺所需的更少的纪律来实现这一目标。将原始承诺与async一起使用通常没有意义。此外，在同一测试中同时测试成功和失败的请求是没有意义的，预期的响应应该是预先确定的。

仅当errorMessage是同步引发错误的函数时，expect(errorMessage).toThrowError(Error)才有效。如果fetchAllUsersData拒绝errorMessage对象，它将无法按预期工作。

它可能应该在一个测试中：

test("...", async () => {
const usersRetrieved = await fetchAllUsersData();
...
expect(users).toMatchObject(userModel);
});

在另一个测试中：

test("...", async () => {
await expect(fetchAllUsersData()).rejects.toThrowError(Error);
});

此外，如果您测试自己在__mock__中提供的测试代码，则测试没有好用。他们应该测试生产代码。