Test the parsing of the mix-blend-mode property. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". Too many parameters : overlay overlay PASS cssRule.type is 1 PASS declaration.length is 0 PASS declaration.getPropertyValue('mix-blend-mode') is null Wrong type : "5px" PASS cssRule.type is 1 PASS declaration.length is 0 PASS declaration.getPropertyValue('mix-blend-mode') is null Trailing comma : overlay, PASS cssRule.type is 1 PASS declaration.length is 0 PASS declaration.getPropertyValue('mix-blend-mode') is null PASS successfullyParsed is true TEST COMPLETE