test_parser: have a list of operations expected to work

instead of guessing.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
test_parser: stop testing unsupported operations

while this happens to work right now, it will stop working when
we re-expose "len" and friends, which are only available after
parse or serialize.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>