Fertility Test

Can someone tell me what fertility test in men entails? Is it different from sperm count test? And if it has to be sperm count test what's the best way to produce the sperm because I'm a virgin and the only way sperm leaves me is during the night when I am asleep, through wetdreams. I don't normally have that experience these days, and even if there's no way to collect that. 

The fertility test result is a pre-requsite for marriage in my fiancee's church.

Any help?