tests: Add message output format tests
tests: Add message output format tests

Signed-off-by: Jakub Hrozek <17cd138b925932d6ed84ede56550124a0b538ee0@posteo.se>

dsch/cmocka,jamesmunns/CMocka,clibs/cmocka,tyc/cmocka,JonathonReinhart/cmocka,clibs/cmocka,VladimirTyrin/cmocka,VladimirTyrin/cmocka,tyc/cmocka,jamesmunns/CMocka,wingyplus/cmocka,JonathonReinhart/cmocka,wingyplus/cmocka,tyc/cmocka,dsch/cmocka