英文:
How We can mock test multiple api calls in jest testing
问题
我有一个情景，需要调用第一个API，然后根据第一个API的响应来调用第二个API。
我已经找到了测试第一个API的解决方案：
global.fetch = jest
.fn()
.mockImplementation(() => getMockPromise({ Response: resMock }));
我在模拟中获得了第一个响应，但如何获得第二个响应呢？我正在使用TypeScript和React。
我尝试在多个地方搜索，但只找到了用于Jest测试的一次模拟响应的解决方案，就像下面这样：
global.fetch = jest
.fn()
.mockImplementation(() => getMockPromise({ Response: resMock }));
我以为如果我使用上述的mockImplementation两次来处理不同的响应，它会起作用，但仍然只有一个起作用。
英文:
I have a scenario like i have to call 1stAPI then depending on the response of 1st API i have to call 2nd API.
I got a solution to test 1st API :
global.fetch = jest
.fn()
.mockImplementation(() => getMockPromise({ Response: resMock }));
I got my 1st response while mocking
but how can I get response in second ? I am using typescript with react
I tried to search multiple places but only got solution for one mock response only for jest testing like below :
global.fetch = jest
.fn()
.mockImplementation(() => getMockPromise({ Response: resMock }));
I thought if I use the above mockImplementation two times for different response it will work, but still same only one is working.
答案1
得分: 0
如果您每次调用 fetch() 时都使用不同的参数，可以使用模拟实现，根据接收到的参数返回不同的数据。
// 测试文件
const mockedResponses = {
'firstUrl': {}, // 第一个响应对象
'secondUrl': {}, // 第二个响应对象
}
global.fetch = jest
.fn()
.mockImplementation((url: string) => getMockPromise({ Response: mockedResponses[url] }));
通常，将实际的 fetch() 调用放在单独的函数内部是个好主意，例如 callFirstApi() 和 callSecondApi()，然后您可以对这些函数进行模拟。这还意味着您不会覆盖全局函数。
您还可以查看类似 Nock 包这样的工具，它允许您对外部 API 进行更复杂的测试。
英文:
If you are calling fetch() with different arguments each time, you can use a mock implementation that responds with different data depending on the argument it receives.
//test file
const mockedResponses = {
'firstUrl': {}, // first response object
'secondUrl': {}, // second response object
}
global.fetch = jest
.fn()
.mockImplementation((url: string) => getMockPromise({ Response: mockedResponses[url] }));
Generally it's a good idea to have the actual fetch() call be done inside a separate function, e.g. callFirstApi() and callSecondApi(), and then you can just mock those functions instead. This also means you don't end up overwriting a global function.
You can also look into something like the Nock package which lets you do more elaborate testing of external APIs.
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