I want to test the background image is correct on my website using Nightwatch, but its set to be the background of a ::before pseudo element, here is the CSS

.icon-circle-delete:before {
    content: '';
    background: url(images/svg/delete.svg) no-repeat 50% 50%;
    display: inline-block;
    width: 16px;
    height: 16px;

I’ve tried the following:

.assert.cssProperty("i.icon-circle-delete", "background", "url(clientlib-site/images/svg/delete.svg) ");

.assert.cssProperty("i.icon-circle-delete:before", "background", "url(images/svg/delete.svg) ");

.assert.cssProperty("i.icon-circle-delete::before", "background", "url(images/svg/delete.svg) ");

.assert.cssProperty("i.icon-circle-delete", "before:background", "url(images/svg/delete.svg) ");

Trying without adding ‘before’ in some way fails, stating that background doesnt contain the URL, as the <i> has it’s own styling. Trying with ‘before’ included in the CSS selector returns that the element cannot be found

Is there a way to test the CSS properties when ::before and ::after pseudo elements are used?