svelte/test/runtime/samples/dev-warning-readonly-computed/_config.js

export default {
	compileOptions: {
		dev: true
	},

	props: {
		a: 42
	},

	test({ assert, component }) {
		try {
			component.foo = 1;
			throw new Error( 'Expected an error' );
		} catch ( err ) {
			assert.equal( err.message, "<Main>: Cannot set read-only property 'foo'" );
		}
	}
};