Quasar Unknown custom element error in unit test - vue.js

Question

I have a simple Vue component that uses Quasar button
<template>
<div>
<span class="count">{{ count }}</span>
<q-btn #click="increment">Increment</q-btn>
</div>
</template>
<script>
export default {
name: 'TestComponent',
data() {
return {
count: 0,
};
},
methods: {
increment() {
this.count += 1;
},
},
};
</script>
I create a unit test for it
import { mount, createLocalVue } from '#vue/test-utils';
import { Quasar, QBtn } from 'quasar';
import TestComponent from '../TestComponent';
describe('TestComponent', () => {
let wrapper;
beforeEach(() => {
const localVue = createLocalVue();
localVue.use(Quasar, { components: { QBtn } });
wrapper = mount(TestComponent, { localVue });
});
it('renders the correct markup', () => {
expect(wrapper.html()).toContain('<span class="count">0</span>');
});
// it's also easy to check for the existence of elements
it('has a button', () => {
expect(wrapper.contains('button')).toBe(true);
});
});
My problem:
If I run the test cases (it function) one by one at a time the test will pass. For example, remove the second it('has a button'...) then run the test. It'll pass. It's the same when removing the first it('renders the correct markup'...)
However, If I keep all test cases then run the test. The second test case will fail with an error
console.error node_modules/vue/dist/vue.common.dev.js:630
[Vue warn]: Unknown custom element: <q-btn> - did you register the component correctly? For recursive components, make sure to provide the "name" option.
found in
---> <TestComponent>
<Root>
What am I doing wrong?

Answer 1

Try removing the before-each. I saw this problem too. Can't remember what exactly fixed it but this is how I have my describe block.
describe('Mount Quasar', () => {
const localVue = createLocalVue()
localVue.use(Quasar, { components })
const wrapper = shallowMount(Register, {
localVue,
stubs: ['router-link', 'router-view']
})
const vm = wrapper.vm
it('passes the sanity check and creates a wrapper', () => {
expect(wrapper.isVueInstance()).toBe(true)
})
})

Answer 2

You will need to import quasar into either webpack, babel, or jest.
In the jest.config.js file
Add
moduleNameMapper: {
quasar: "quasar-framework/dist/umd/quasar.mat.umd.min.js"
},