.test-invalid-params {
	background-image-1: image-set();
	background-image-2: image-set(
		url(img/test.png)
	);
	background-image-3: image-set(
		1x
	);
}

.test-invalid-commas {
	background-image-1: image-set(
		url(img/test.png) 1x,
	);
	background-image-2: image-set(
		url(img/test.png) 1x,
		url(img/test-2x.png) 2x,
	);
}

.test-invalid-images {
	background-1: image-set(
		image-set(
			url(img/test.png) 1x
		) 1x
	);
	background-2: image-set(
		calc(1rem + 1px) 1x
	);
}

.test-invalid-resolutions {
	background-image-1: image-set(
		url(img/test.png) 1
	);
	background-image-2: image-set(
		url(img/test.png) 1omg
	);
}
