Jest asses called functions - jestjs

Question

I am testing my graphql endpoint with Jest. Basically I am assessing the result returned from resolver. But in this case, I want to test if a function has been called inside the resolver with particular parameter. The code is something like
import { sendLib } from '../lib'
export default {
send: async (input) => {
const data = {
foo: 1,
bar: 2,
...input
}
await sendLib(data)
return { input }
}
}
I want to make sure sendLib() is called with data parameter. The most important thing is I need to test if data has correct values. I have been reading the Jest's .toHaveBeenCalledWith() but I can't figured out how it fits my case.
Also is there a way to do that test without being actually executing sendLib()? Because the function calls a HTTP request and I don't really want to waste time to do that on testing.

Answer 1

you should mock lib in your test wit jest.fn that way it would not call your actual function implementation or perform http request. instead it would call the mock function. and you can assert what it was called with below is a rough example of what i'm tall
// filetotest.js
import { sendLib } from '../lib'
export default {
send: async (input) => {
const data = {
foo: 1,
bar: 2,
...input
}
await sendLib(data)
return { input }
}
}
//__tests__/filetotest.test.js
import { sendLib } from '../../lib'
import defaultImport from '../filetotest.js'
jest.mock('../../lib/', () => {
return {
sendLib: jest.fn()
}
})
test('call with correct data', async () => {
// call the function you are suppose to to test
await defaultImport()
// sendLib is a mockFn as jest.mock calls are hoisted
expect(SendLib).toHaveBeenCalledWith({data: ''})
})