测试 redux-saga 的“all”效果的最佳方法是什么？

Question

我有一个传奇，目前有一个yield all(...)，我正在尝试找出如何测试以查看我实际上正在使用all()正确的函数进行调用。这是我正在使用的内容的精简版本：

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function* start() {\n  // I\'d prefer not to start the status polling and the listening for\n  // the cancellation until after the request has been submitted, but\n  // I\'m having trouble figuring out how to do that. So I\'m just going\n  // to listen for \'em all up front here until I\'m smarter.\n  yield all([\n    waitForCreateRequest(),\n    waitForPollStatus(),\n    waitForCancelRequest(),\n  ])\n}\n\nfunction* waitForCreateRequest() {\n  while ( true ) {  \n    try {\n      const { payload } = yield take(\'CREATE_REQUEST\')\n      // ...\n    } catch ( error ) {\n      // ...\n    }\n  }\n}\n\nfunction* waitForPollStatus() {\n  while ( true ) {  \n    try {\n      const { payload } = yield take(\'POLL_STATUS\')\n      // ...\n    } catch ( error ) {\n      // ...\n    }\n  }\n}\n\nfunction* waitForCancelRequest() {\n  while ( true ) {  \n    try {\n      yield take(\'CANCEL_REQUEST\')\n      // ...\n    } catch ( error ) {\n      // ...\n    }\n  }\n}\n

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我编写的测试（使用 Mocha 和bdd-lazy-var）是这样的：

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describe(\'MySaga\', () => {\n  describe(\'*start()\', () => {\n    subject(start())\n\n    it(\'calls `all()` with the correct functions\', () => {\n      expect($subject.next().value).to.eql(all([\n        waitForSubmitExportRequest(),\n        waitForPollExportStatus(),\n        waitForCancelExportRequest(),\n      ]))\n    })\n  })\n})\n

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没有输出——它只是挂起......然后我收到“JavaScript 堆内存不足”错误。

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如果我console.log($subject.next().value)改为：

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describe(\'MySaga\', () => {\n  describe(\'*start()\', () => {\n    subject(start())\n\n    it.only(\'foo\', () => {\n      console.log($subject.next().value)\n    })\n  })\n})\n

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这就是我得到的：

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  MySaga\n    *start()\n{ \'@@redux-saga/IO\': true,\n  ALL: \n   [ GeneratorFunctionPrototype { _invoke: [Function: invoke] },\n     GeneratorFunctionPrototype { _invoke: [Function: invoke] },\n     GeneratorFunctionPrototype { _invoke: [Function: invoke] } ] }\n      \xe2\x9c\x93 foo\n

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所以我不确定这里发生了什么。

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无数的谷歌搜索并没有真正找到任何有用的东西，而且我发现的最接近的SO帖子（how to test redux-saga alleffect using jest）也没有帮助。

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Answer 1

start您的函数不是生成器函数，这是一个拼写错误吗？

反正。你能尝试start像这样重写你的函数吗：

function* start() {
  yield all([
    call(waitForCreateRequest),
    call(waitForPollStatus),
    call(waitForCancelRequest),
  ])
}

现在您的测试可能如下所示：

it('calls `all()` with the correct functions', () => {
  expect($subject.next().value).to.eql(all([
    call(waitForSubmitExportRequest),
    call(waitForPollExportStatus),
    call(waitForCancelExportRequest),
  ]))
})