在使用jest进行单元测试时，如何模拟普通对象的依赖关系？
在使用jest进行单元测试时，如何模拟普通对象的依赖关系？
提问于 2019-11-07 18:37:09
在测试我的ReactJs助手时，我找不到模拟对象导入的方法。所有的例子都展示了如何模拟导入的函数，没有人谈到模拟导入的对象。
我想模拟的这个基础辅助对象：
filters-state.helper.ts
export const FiltersStateHelper = {
toggleFilters: <T extends FiltersState>(state: T): T => ({
...state,
isOpen: !state.isOpen
})
};我正在测试的state helper中使用它：
search-view-state.helper.ts
import { FiltersStateHelper } from 'shared/filters/helpers/filters-state.helper';
export const SearchViewStateHelper = {
toggleFilters: <T extends SearchViewState>(state: T): T => ({
...state,
filters: FiltersStateHelper.toggleFilters(state.filters)
})
//... more methods
};在测试中，模仿依赖关系失败了，可能是因为我的助手的依赖关系在我说出要模仿什么之前就已经解决了：
search-view-state.helper.spec.ts
import { SearchViewStateHelper as helper } from 'shared/search-view/helpers/search-view-state.helper';
describe('toggleFilters method', () => {
const spy = jest.fn();
jest.doMock('shared/filters/helpers/filters-state.helper', () => {
return {
toggleFilters: spy
};
});
const state = {};
it('should toggle filters', () => {
helper.toggleFilters(state);
expect(spy).toHaveBeenCalled();
});
});回答 1
Stack Overflow用户
发布于 2019-11-08 12:58:19
您可以使用jest.spyOn(object, methodName, accessType?)来窥探FiltersStateHelper对象的toggleFilters方法。
例如。
filters-state.helper.ts
type FiltersState = any;
export const FiltersStateHelper = {
toggleFilters: <T extends FiltersState>(state: T): T => ({
...state,
isOpen: !state.isOpen
})
};search-view-state.helper.ts
import { FiltersStateHelper } from './filters-state.helper';
type SearchViewState = any;
export const SearchViewStateHelper = {
toggleFilters: <T extends SearchViewState>(state: T): T => ({
...state,
filters: FiltersStateHelper.toggleFilters(state.filters)
})
// ... more methods
};search-view-state.helper.spec.ts
import { SearchViewStateHelper as helper } from './search-view-state.helper';
import { FiltersStateHelper } from './filters-state.helper';
describe('toggleFilters method', () => {
const state = { filters: { isOpen: false } };
it('should toggle filters', () => {
const spy = jest.spyOn(FiltersStateHelper, 'toggleFilters');
helper.toggleFilters(state);
expect(spy).toHaveBeenCalled();
expect(spy).toBeCalledWith({ isOpen: false });
});
});100%覆盖率的单元测试结果：
PASS src/stackoverflow/58746881/search-view-state.helper.spec.ts
toggleFilters method
✓ should toggle filters (6ms)
-----------------------------|----------|----------|----------|----------|-------------------|
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |
-----------------------------|----------|----------|----------|----------|-------------------|
All files | 100 | 100 | 100 | 100 | |
filters-state.helper.ts | 100 | 100 | 100 | 100 | |
search-view-state.helper.ts | 100 | 100 | 100 | 100 | |
-----------------------------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 3.833s, estimated 8s源代码：https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/58746881
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/58746881
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