[英]Testing of useEffect hook with try/catch
我需要在获取数据请求拒绝时测试catch
,但我不明白为什么没有捕获错误并且我收到了这个错误: 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(). (rejection id: 2)
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(). (rejection id: 2)
我有这样的情况:
export const Container = ({fetchFirstAsset, fetchSecondAsset}) => {
const [status, setStatus] = useState(null);
async function fetchAssets() {
setStatus(IN_PROGRESS);
try {
await fetchFirstAsset();
await fetchSecondAsset()
setStatus(SUCCESS);
} catch {
setStatus(FAILURE);
}
}
useEffect(() => {
fetchAssets();
}, []);
....
};
并像这样测试:
import {mount} from 'enzyme';
import {act} from 'react-dom/test-utils';
const fetchFirstAsset = jest.fn();
const fetchSecondAsset = jest.fn();
it('should render without errors', async () => {
fetchFirstAsset.mockReturnValueOnce(Promise.resolve());
fetchSecondAsset.mockReturnValueOnce(Promise.reject());
let component;
await act(async () => {
component = mount(
<Container
fetchFirstAsset={fetchFirstAsset}
fetchSecondAsset={fetchSecondAsset}
/>
);
});
expect(fetchSomething).toHaveBeenCalled();
});
If I test case when fetchSomething
with Promise.resolve()
evertyhing works fine and tests are correct but when I try to Promise.reject()
in order to test catch
case then this error is not catched and I have unhandled promise rejection
. (为什么代码看起来像这样:在应用程序的其他地方,我使用 redux 处理状态更改,因此对 catch 的测试很容易,但在一个地方我需要为组件获取 3 个不同的资产,我决定使用useState
因为从 redux 中提取 3 个不同的状态并将其组合起来会很丑,我认为useState
更干净)
在此先感谢您的帮助::)
我遇到了同样的问题,即在 useEffect() 中使用 try/catch 子句时不起作用。 我做了一些搜索,看来这是一个潜在的错误,请查看:
https://github.com/testing-library/react-hooks-testing-library/issues/305
也就是说,我能够解决以下问题:
失败示例:
useEffect(() => {
try {
invokeMyAsyncFunction();
setStatus(SUCCESS);
} catch (e) {
setStatus(FAILURE); // <== will not be invoked on exception!!
}
}
成功案例:
useEffect(() => {
invokeMyAsyncFunction()
.then((response:any) => {
setStatus(SUCCESS);
})
.catch((e) => {
setStatus(FAILURE); // <== this **WILL** be invoked on exception
});
}
你需要像这样编写你的catch块:
catch (e) {
// can do something with e in here
setStatus(FAILURE);
}
这很好,您需要在 useEffect 中声明您的 function 并在其中实现 try/catch 块,在 function 之外您只需调用它
(另外,别忘了清理你的使用效果)
useEffect(() => {
const fetchAssets = async () => {
setStatus(IN_PROGRESS);
try {
await fetchFirstAsset();
await fetchSecondAsset()
setStatus(SUCCESS);
} catch {
setStatus(FAILURE);
}
}
fetchAssets();
}, []}
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