addrinfo.ai_protocol was not set on Cygwin.
MODIFY
mrbgems/mruby-socket/test/socket.rb
mrbgems/mruby-socket/test/socket.rb
@@ -15,7 +15,7 @@ assert('Socket::getaddrinfo') do
assert_equal "127.0.0.1", a[3]
assert_equal Socket::AF_INET, a[4]
assert_equal Socket::SOCK_DGRAM, a[5]
- assert_equal Socket::IPPROTO_UDP, a[6]
+ assert_equal Socket::IPPROTO_UDP, a[6] unless SocketTest.cygwin?
end
assert('Socket#recvfrom') do

addrinfo.ai_protocol was not set on Cygwin.