This test makes sure that constructing a FontFace with empty strings is the same as omitting those strings. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS fontface = new FontFace('WebFont', 'url(\'asdf\')', {style: ''}) did not throw exception. PASS fontface.style is "normal" PASS fontface.style = '' threw exception SyntaxError: The string did not match the expected pattern.. PASS fontface = new FontFace('WebFont', 'url(\'asdf\')', {weight: ''}) did not throw exception. PASS fontface.weight is "normal" PASS fontface.weight = '' threw exception SyntaxError: The string did not match the expected pattern.. PASS fontface = new FontFace('WebFont', 'url(\'asdf\')', {unicodeRange: ''}) did not throw exception. PASS fontface.unicodeRange is "U+0-10ffff" PASS fontface.unicodeRange = '' threw exception SyntaxError: The string did not match the expected pattern.. PASS fontface = new FontFace('WebFont', 'url(\'asdf\')', {featureSettings: ''}) did not throw exception. PASS fontface.featureSettings is "normal" PASS fontface.featureSettings = '' threw exception SyntaxError: The string did not match the expected pattern.. PASS fontface.family = '' threw exception SyntaxError: The string did not match the expected pattern.. PASS successfullyParsed is true TEST COMPLETE