Enhance the test coverage part-14 : dubbo-remoting/dubbo-remoting-mina(dubbo-remoting-netty/dubbo-remoting-netty4) modules

[lovepoem]

add unit to the modules
dubbo-remoting/dubbo-remoting-mina
dubbo-remoting/dubbo-remoting-netty
dubbo-remoting/dubbo-remoting-netty4

[DeadLion]

i'd like to handle this issue, do we have a deadline?

[lovepoem]

ok，the quality of test code has the highest priority。Deadline ：before the end of May