如何使用Redux Saga测试API请求失败? [英] How to test API request failures with Redux Saga?
问题描述
我正在尝试测试我的传奇可以遵循的每个场景,但我无法实现我想要的行为。
这很简单,我有一个HTTP请求(登录),我想通过模拟我的API方法测试成功和失败案例。
I am trying to test every scenarios my saga could follow, but i am not able to make happens the behaviors i want. This is pretty simple, i have a HTTP request (login), and i want to test the success and the failure cases by mocking my API method.
但是,看起来调用效果
不会触发我的api函数,我还没有真正了解它是如何工作的,但我想中间件是负责的调用该函数,因为我不通过我的测试商店,我无法得到结果。
But, it looks like the call effect
doesn't fire my api function, i don't really get yet how it works, but i guess that the middleware is in charge of invoking the function, and since i don't go though the store on my test, i can't get the result.
所以我的问题是,你怎么测试当您需要在异步调用旁边发送不同的操作(通常是成功或失败)时,您的传奇是什么?
So my question is, how can you test your saga when you need to dispatch different actions (typically success or failure) next to your async call ?
我找了一个例子,我发现sagas成功但失败但失败案例从未经过测试,例如在购物车示例中这里
I looked for an example, i found sagas with success and fail but the fail case is never tested, for example in the shopping cart example here
SAGA.JS
export function* login(action) {
try {
const user = yield call(api.login, action);
return yield put(actions.loginSuccess(user));
} catch(e) {
yield put(actions.loginFail(e));
}
}
export default function* rootAuthenticationSagas() {
yield* takeLatest(LOGIN, login);
}
TEST.JS
describe('login', () => {
context('When it fails', () => {
before('Stub the api', () => {
sinon.stub(api, 'login', () => {
// IT NEVER COMES HERE !
return Promise.reject({ error: 'user not found' });
});
});
it('should return a LOGIN_FAIL action', () => {
const action = {
payload: {
name: 'toto',
password: '123456'
}
};
const generator = login(action);
// THE CALL YIELD
generator.next();
const expectedResult = put({ type: 'LOGIN_FAIL', payload: { error: 'user not found' } });
expect(generator.next().value).to.be.eql(expectedResult); // FAIL BECAUSE I GET A LOGIN_SUCCESS INSTEAD OF A FAIL ONE
});
});
});
推荐答案
马克的回答是正确的。中间件执行这些指令。但是这会让你的生活变得更轻松:在测试中,你可以提供你想要的任何东西作为 next()
的参数,并且生成器函数将会因 yield
而收到它。这正是saga中间件的作用(除了它实际上是激发请求而不是给你一个假响应)。
Mark’s answer is correct. Middleware executes those instructions. But this makes your life easier: in the test, you can provide whatever you want as the argument to next()
, and the generator function will receive it as a result of yield
. This is exactly what saga middleware does (except that it actually fires up a request instead of giving you a fake response).
使 yield
获取一个任意值,将其传递给 next()
。要使其接收错误,请将其传递给 throw()
。在您的示例中:
To make yield
get an arbitrary value, pass it to next()
. To make it "receive" an error, pass it to throw()
. In your example:
it('should return a LOGIN_FAIL action', () => {
const action = {
payload: {
name: 'toto',
password: '123456'
}
};
const generator = login(action);
// Check that Saga asks to call the API
expect(
generator.next().value
).to.be.eql(
call(api.login, action)
);
// Note that *no actual request was made*!
// We are just checking that the sequence of effects matches our expectations.
// Check that Saga reacts correctly to the failure
expect(
generator.throw({
error: 'user not found'
}).value
).to.be.eql(
put({
type: 'LOGIN_FAIL',
payload: { error: 'user not found' }
})
);
});
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