The default values for 'width' and 'height' are '100%' and 'x' and 'y' are '0' for the 'svg' element.
Empty 'svg' element is referenced via 'getElementById()'. From that reference, 'width', 'height', 'x', and 'y' are evaluated via 'baseVal.valueAsString'. A failure of one or more tests is indicated by the word 'FAIL' in red text.
Test passes if there is no red visible on the page.