This is a testharness.js-based test.
[FAIL] ":host(:is(div .foo))" should be a valid selector
assert_equals: serialization should be canonical expected ":host(:is(div .foo))" but got ":host(:is())"
[FAIL] ":host(:where(div .foo))" should be a valid selector
assert_equals: serialization should be canonical expected ":host(:where(div .foo))" but got ":host(:where())"
[FAIL] ":is(::before)" should be a valid selector
assert_equals: serialization should be canonical expected ":is(::before)" but got ":is()"
[FAIL] ":where(::before)" should be a valid selector
assert_equals: serialization should be canonical expected ":where(::before)" but got ":where()"
[FAIL] "::part(foo):is([attr='value'])" should be a valid selector
assert_equals: serialization should be canonical expected "::part(foo):is([attr='value'])" but got "::part(foo):is()"
[FAIL] "::part(foo):where([attr='value'])" should be a valid selector
assert_equals: serialization should be canonical expected "::part(foo):where([attr='value'])" but got "::part(foo):where()"
[FAIL] ":is(# C4єанйтж╕/┘ГÐжЮХєа▓â”ÐÐБМєаСеÐÐЖÐ%=[Ñмм0)" should be an invalid selector
assert_throws_dom: ":is(# C4єанйтж╕/┘ГÐжЮХєа▓â”ÐÐБМєаСеÐÐЖÐ%=[Ñмм0)" should throw in querySelector function "() => document.querySelector(selector)" did not throw
Harness: the test ran to completion.