Javascript 如何在每次测试之前重置 Jest 模拟函数调用计数
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How to reset Jest mock functions calls count before every test
提问by Alex Efremov
I'm new to Jest, I'm trying to use it for testing if a function was called or not. I noticed the mock.calls.length is not resetting for every test but accumulating. How can I make it 0 before every test? I don't want my next tests depends on the results of the previous.
我是 Jest 的新手，我试图用它来测试一个函数是否被调用。我注意到 mock.calls.length 并没有为每个测试重置，而是在累积。如何在每次测试前将其设为 0？我不希望我的下一个测试取决于前一个的结果。
I know there is beforeEach in Jest - should I use it? What is the best way to reset mock.calls.length? Thank you.
我知道 Jest 中有 beforeEach - 我应该使用它吗？重置 mock.calls.length 的最佳方法是什么？谢谢你。
A code example:
一个代码示例：
Sum.js:
总和.js：
import local from 'api/local';
export default {
addNumbers(a, b) {
if (a + b <= 10) {
local.getData();
}
return a + b;
},
};
Sum.test.js
Sum.test.js
import sum from 'api/sum';
import local from 'api/local';
jest.mock('api/local');
// For current implementation, there is a difference
// if I put test 1 before test 2. I want it to be no difference
// test 1
test('should not to call local if sum is more than 10', () => {
expect(sum.addNumbers(5, 10)).toBe(15);
expect(local.getData.mock.calls.length).toBe(0);
});
// test 2
test('should call local if sum <= 10', () => {
expect(sum.addNumbers(1, 4)).toBe(5);
expect(local.getData.mock.calls.length).toBe(1);
});
回答by Alex Efremov
One way I found to handle it: to clear mock function after each test:
我发现处理它的一种方法：在每次测试后清除模拟功能：
To add to Sum.test.js:
添加到 Sum.test.js：
afterEach(() => {
local.getData.mockClear();
});
If you'd like to clear all mock functions after each test, use clearAllMocks
如果您想在每次测试后清除所有模拟功能，请使用clearAllMocks
afterEach(() => {
jest.clearAllMocks();
});
回答by Daniel Marín
As @AlexEfremov pointed in the comments. You may want to use clearAllMocksafter each test:
正如@AlexEfremov 在评论中指出的那样。您可能希望clearAllMocks在每次测试后使用：
afterEach(() => {
jest.clearAllMocks();
});
Take in mind this will clear the call count of every mock function you have, but that is probably the right way.
请记住，这将清除您拥有的每个模拟函数的调用计数，但这可能是正确的方法。
