How to set mock nuxt asyncData in jest - vue.js

Question

I am using Nuxt.js and want to test my page which uses asyncData with Jest. I have a factory function to set up my wrapper, but it basically returns a shallowMount.
Expected
When clicking a button I want the function to behave differently depending on the query parameter. When running the test I want to mock this by setting it directly when creating the wrapper (Similar to setting propsData). E.g. const wrapper = factory({ propsData: { myQueryParam: 'some-value' } });
Result
However trying to set propsData still returns undefined: console.log(wrapper.vm.myQueryParam); // undefined while I would expect it to be 'some-value'
Question
Is there a different approach on how I can test this function that relies on query parameters?

Answer 1

Because asyncData is called before Vue is initialised, it means shallowMount doesn't work right out of the box.
Example:
page:
<template>
<div>Your template.</div>
</template>
<script>
export default {
data() {
return {}
},
async asyncData({
params,
error,
$axios
}) {
await $axios.get("something")
}
}
</script>
test:
import { shallowMount } from "#vue/test-utils";
describe('NewsletterConfirm', () => {
const axiosGetMock = jest.fn()
const axiosPostMock = jest.fn()
var getInitialised = async function (thumbprint) {
if (thumbprint == undefined) throw "thumbprint not provided"
let NewsletterConfirm = require('./_thumbprint').default
if (!NewsletterConfirm.asyncData) {
return shallowMount(NewsletterConfirm);
}
let originalData = {}
if (NewsletterConfirm.data != null) {
originalData = NewsletterConfirm.data()
}
const asyncData = await NewsletterConfirm.asyncData({
params: {
thumbprint
},
error: jest.fn(),
$axios: {
get: axiosGetMock,
post: axiosPostMock
}
})
NewsletterConfirm.data = function () {
return {
...originalData,
...asyncData
}
}
return shallowMount(NewsletterConfirm)
}
it('calls axios', async () => {
let result = await getInitialised("thumbprint")
expect(axiosGetMock).toHaveBeenCalledTimes(1)
});
});
Credits to VladDubrovskis for his comment: in this nuxt issue