Vue.js unit testing ErrorBoundary - unit-testing

Question

I've built simple ErrorBoundary component for my project in Vue.js and I'm struggling to write unit test for it. Component's code below:
<template>
<div class="overvue-error-boundary">
<slot v-if="!error" />
<div class="error-message" v-else>Something went horribly wrong here.</div>
</div>
</template>
<script>
export default {
data () {
return {
error: false
}
},
errorCaptured (error, vm, info) {
this.error = true;
}
}
</script>
I've created an ErrorThrowingComponent that throws an error on created() lifecycle hook so I can test ErrorBoundary:
const ErrorThrowingComponent = Vue.component('error-throwing-component', {
created() {
throw new Error(`Generic error`);
},
render (h) {
return h('div', 'lorem ipsum')
}
});
describe('when component in slot throws an error', () => {
it('renders div.error-message', () => {
// this is when error is when 'Generic error' is thrown by ErrorThrowingComponent
const wrapper = shallowMount(OvervueErrorBoundary, {
slots: {
default: ErrorThrowingComponent
}});
// below code is not executed
expect(wrapper.contains(ErrorThrowingComponent)).to.be.false;
expect(wrapper.contains('div.error-message')).to.be.true;
});
});
The problem is that ErrorThrowingComponent throws an error when I'm trying to actually mount it (thus failing entire test). Is there any way I can prevent this from happening?
EDIT: What I'm trying to achieve is to actually mount the ErrorThrowing component in a default slot of ErrorBoundary component to assert if ErrorBoundary will render error message and not the slot. This is way I created the ErrorThrowingComponent in the first place. But I cannot assert ErrorBoundary's behavior, because I get an error when trying to create a wraper.

Answer 1

For anyone comming here with a similar problem: I've raised this on Vue Land's #vue-testing channel on Discord, and they suggested to move entire error-handling logic to a function which will be called from the errorCaptured() hook, and then just test this function. This approach seems sensible to me, so I decided to post it here.
Refactored ErrorBoundary component:
<template>
<div class="error-boundary">
<slot v-if="!error" />
<div class="error-message" v-else>Something went horribly wrong here. Error: {{ error.message }}</div>
</div>
</template>
<script>
export default {
data () {
return {
error: null
}
},
methods: {
interceptError(error) {
this.error = error;
}
},
errorCaptured (error, vm, info) {
this.interceptError(error);
}
}
</script>
Unit test using vue-test-utils:
describe('when interceptError method is called', () => {
it('renders div.error-message', () => {
const wrapper = shallowMount(OvervueErrorBoundary);
wrapper.vm.interceptError(new Error('Generic error'));
expect(wrapper.contains('div.error-message')).to.be.true;
});
});