vitest and svelte component's onMount

[csandeep]

I'm trying to use Svelte to create a simple reactive component. The component loads data from an api server onMount and updates a reactive value (which updates a html element).

I have a simple vitest that renders the component and verifies the value of the html element. However while running under vitest the onMount is never called and hence the api call is never made. What am I missing ?

Component.svelte:

<script>
	import { onMount } from 'svelte';

	export let name = 'world';

	onMount(async () => {
		console.log('chat onMount event!');
		const response = await fetch('http://localhost:8081/api');
        // for this example, assume name returned by api is FOO
		name = data.name;
	});

</script>

<div id="#element">
	<b> Hello {name}</b>
</div>

index.test.js:

import { expect, test } from 'vitest';
import '@testing-library/jest-dom';
import { render, screen } from '@testing-library/svelte';
import Component from '../src/lib/Component.svelte';

test('should render', () => {
	render(Component);

	const heading = screen.getByText('Hello FOO');
	expect(heading).toBeInTheDocument();
});

[csandeep]

Seems to be related to testing-library/svelte-testing-library#222 , still not sure if its a vitest issue or a issue with testing-library/svelte-testing-library -- happy to close this if anyone feels otherwise.

[AriPerkkio]

There's more discussion about this at #2834. There are various work-arounds mentioned on that issue.