Javascript 如何正确地使模拟在 Jest 中抛出错误？
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How to properly make mock throw an error in Jest?
提问by Le garcon
I'm testing my GraphQL api using Jest.
我正在使用 Jest 测试我的 GraphQL api。
I'm using a separate test suit for each query/mutation
我为每个查询/突变使用单独的测试套装
I have 2 tests (each one in a separate test suit) where I mock one function (namely, Meteor's callMethod) that is used in mutations.
我有 2 个测试（每个测试都在一个单独的测试套件中），我模拟了一个callMethod用于突变的函数（即 Meteor's ）。
it('should throw error if email not found', async () => {
callMethod
.mockReturnValue(new Error('User not found [403]'))
.mockName('callMethod');
const query = FORGOT_PASSWORD_MUTATION;
const params = { email: '[email protected]' };
const result = await simulateQuery({ query, params });
console.log(result);
// test logic
expect(callMethod).toBeCalledWith({}, 'forgotPassword', {
email: '[email protected]',
});
// test resolvers
});
When I console.log(result)I get
当console.log(result)我得到
{ data: { forgotPassword: true } }
This behaviour is not what I want because in .mockReturnValueI throw an Error and therefore expect resultto have an error object
这种行为不是我想要的，因为.mockReturnValue我抛出了一个错误，因此期望result有一个错误对象
Before this test, however, another is ran
然而，在此测试之前，运行了另一个
it('should throw an error if wrong credentials were provided', async () => {
callMethod
.mockReturnValue(new Error('cannot login'))
.mockName('callMethod');
And it works fine, the error is thrown
它工作正常，错误被抛出
I guess the problem is that mock doesn't get reset after the test finishes.
In my jest.conf.jsI have clearMocks: true
我想问题是测试完成后模拟不会重置。在我的jest.conf.js我有 clearMocks: true
Each test suit is in a separate file, and I mock functions before tests like this:
每个测试套装都在一个单独的文件中，我在测试之前模拟函数，如下所示：
import simulateQuery from '../../../helpers/simulate-query';
import callMethod from '../../../../imports/api/users/functions/auth/helpers/call-accounts-method';
import LOGIN_WITH_PASSWORD_MUTATION from './mutations/login-with-password';
jest.mock(
'../../../../imports/api/users/functions/auth/helpers/call-accounts-method'
);
describe('loginWithPassword mutation', function() {
...
UPDATE
更新
When I substituted .mockReturnValuewith .mockImplementationeverything worked out as expected:
当我.mockReturnValue用.mockImplementation一切都按预期进行替换时：
callMethod.mockImplementation(() => {
throw new Error('User not found');
});
But that doesn't explain why in another test .mockReturnValueworks fine...
但这并不能解释为什么在另一个测试中.mockReturnValue工作正常......
回答by eduardomoroni
Change .mockReturnValuewith .mockImplementation:
更改.mockReturnValue为.mockImplementation：
yourMockInstance.mockImplementation(() => {
throw new Error();
});
回答by AngularBoy
Accepted answer didn't work for me however this did (Angular + Jest):
接受的答案对我不起作用，但是这样做（Angular + Jest）：
import { throwError } from 'rxjs';
yourMockInstance.mockImplementation(() => {
return throwError(new Error('my error message'));
});
