使用 sinon 时出现不一致的 UnhandledPromiseRejectionWarning
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【中文标题】使用 sinon 时出现不一致的 UnhandledPromiseRejectionWarning【英文标题】:Inconsistent UnhandledPromiseRejectionWarning when using sinon 【发布时间】:2019-03-11 07:03:44 【问题描述】:据我所知,failApiClient
和 explicitFailApiClient
这两个对象应该具有相同的类型,并且记录它们似乎同意:
console.log(failApiClient) // getObjects: [Function: getObjects]
console.log(explicitFailApiClient) // getObjects: [Function: getObjects]
阅读this 问题为我提供了正确处理此问题所需的信息,但它并没有告诉我为什么生成的failApiClient
会导致警告,而explicitFailApiClient
不会。
我已将其缩减到接近重现环境和展示可行替代方案所需的最低要求:
import * as sinon from 'sinon';
import 'source-map-support/register';
class LocalObject
const fakeObject = new LocalObject();
const getFakeApi = (result: Promise<LocalObject[]>) = (getObjects: () => result);
const successObjectClient = getFakeApi(Promise.resolve([fakeObject]));
// These should be equivalent, but the former causes a test error
const failApiClient = getFakeApi(Promise.reject(new Error()));
const explicitFailApiClient =
getObjects(): Promise<LocalObject[]>
return Promise.reject(new Error());
;
describe('successApiClient', () =>
before(() =>
sinon.spy(successObjectClient, 'getObjects');
);
it('does not have a warning', async () =>
// do nothing
);
);
describe('failApiClient', () =>
before(() =>
sinon.spy(failApiClient, 'getObjects');
);
it('should not have a warning', async () =>
// do nothing
);
);
describe('explicitFailApiClient', () =>
before(() =>
sinon.spy(explicitFailApiClient, 'getObjects');
);
it('does not have a warning', async () =>
// do nothing
);
);
还有~/...> tsc && npm test
的结果:
> internal-api@1.0.0 test /Users/./Projects/./node/internal-api
> grunt test
Running "test" task
Running "env:dev" (env) task
Running "simplemocha:unit" (simplemocha) task
(node:72101) UnhandledPromiseRejectionWarning: Error
at Object.<anonymous> (/Users/./Projects/./node/internal-api/src/test/unit/models/mvp.test.ts:21:57)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (/Users/./Projects/./node/internal-api/node_modules/coffee-script/lib/coffee-script/register.js:45:36)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Module.require (module.js:596:17)
at require (internal/module.js:11:18)
at /Users/./Projects/./node/internal-api/node_modules/mocha/lib/mocha.js:222:27
at Array.forEach (<anonymous>)
at Mocha.loadFiles (/Users/./Projects/./node/internal-api/node_modules/mocha/lib/mocha.js:219:14)
at Mocha.run (/Users/./Projects/./node/internal-api/node_modules/mocha/lib/mocha.js:487:10)
at Object.<anonymous> (/Users/./Projects/./node/internal-api/node_modules/grunt-simple-mocha/tasks/simple-mocha.js:29:20)
at Object.<anonymous> (/Users/./Projects/./node/internal-api/node_modules/grunt/lib/grunt/task.js:255:15)
at Object.thisTask.fn (/Users/./Projects/./node/internal-api/node_modules/grunt/lib/grunt/task.js:73:16)
at Object.<anonymous> (/Users/./Projects/./node/internal-api/node_modules/grunt/lib/util/task.js:294:30)
at Task.runTaskFn (/Users/./Projects/./node/internal-api/node_modules/grunt/lib/util/task.js:244:24)
at Task.<anonymous> (/Users/./Projects/./node/internal-api/node_modules/grunt/lib/util/task.js:293:12)
at /Users/./Projects/./node/internal-api/node_modules/grunt/lib/util/task.js:220:11
at _combinedTickCallback (internal/process/next_tick.js:131:7)
at process._tickCallback (internal/process/next_tick.js:180:9)
at Function.Module.runMain (module.js:695:11)
at startup (bootstrap_node.js:191:16)
at bootstrap_node.js:612:3
(node:72101) 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: 1)
(node:72101) [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.
successApiClient
✓ does not have a warning
failApiClient
✓ should not have a warning
(node:72101) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 1)
explicitFailApiClient
✓ does not have a warning
3 passing (14ms)
Done.
【问题讨论】:
【参考方案1】:它们不等价。
在下面的代码中,当 Promise.reject
作为参数时,JS 已经执行了语句,这就是为什么你会收到早期警告 UnhandledPromiseRejectionWarning
。
const failApiClient = getFakeApi(Promise.reject(new Error()));
对比
const explicitFailApiClient =
getObjects(): Promise<LocalObject[]>
return Promise.reject(new Error());
;
在调用explicitFailApiClient.getObjects()
时将评估其Promise.reject
。
解决方案
这是我针对此问题的替代解决方案。我可以使用来自诗乃的resolves
和rejects
。
const getFakeApi = getObjects: (result) => result;
const getFakeApiStub = sinon.stub(getFakeApi, 'getObjects');
describe('successApiClient', () =>
before(() =>
getFakeApiStub.resolves([fakeObject]); // success and resolves
);
it('does not have a warning', async () =>
// do nothing
);
);
describe('failApiClient', () =>
before(() =>
getFakeApiStub.rejects(new Error()); // make it failed
);
it('should not have a warning', async () =>
// do nothing
);
);
参考: https://sinonjs.org/releases/v6.3.5/stubs/#stubresolvesvalue
希望对你有帮助
【讨论】:
【参考方案2】:Promise 可以是未解决、已解决或拒绝。 “then”用于处理“catch”处理拒绝的解决方案。你在没有抓住它的情况下抛出拒绝。
试试SomePromiseRejection().catch(err => DoSomeStuff(err))
所以在explicitFailApiClient
被调用后有一个.catch
块。
【讨论】:
explicitFailApiClient
不会导致UnhandledPromiseRejectionWarning
- 只有failApiClient
会。这就是我试图理解的症结所在。以上是关于使用 sinon 时出现不一致的 UnhandledPromiseRejectionWarning的主要内容,如果未能解决你的问题,请参考以下文章