failures=0

check() {
	if ! eval "[ $* ]"; then
		echo "Failed: $*"
		: $((failures += 1))
	fi
}

builtin : || echo "Bad return code at $LINENO"
builtin true || echo "Bad return code at $LINENO"
builtin ls 2>/dev/null && echo "Bad return code at $LINENO"
check '"$(builtin pwd)" = "$(pwd)"'
check '-z "$(builtin :)"'
check '-z "$(builtin true)"'
check '-z "$( (builtin nosuchtool) 2>/dev/null)"'
check '-z "$(builtin nosuchtool 2>/dev/null)"'
check '-z "$(builtin nosuchtool 2>/dev/null; :)"'
check '-z "$( (builtin ls) 2>/dev/null)"'
check '-z "$(builtin ls 2>/dev/null)"'
check '-z "$(builtin ls 2>/dev/null; :)"'
check '-n "$( (builtin nosuchtool) 2>&1)"'
check '-n "$(builtin nosuchtool 2>&1)"'
check '-n "$(builtin nosuchtool 2>&1; :)"'
check '-n "$( (builtin ls) 2>&1)"'
check '-n "$(builtin ls 2>&1)"'
check '-n "$(builtin ls 2>&1; :)"'

exit $((failures > 0))