I had a friend who had had unprotected sexual intercourse who needed to get tested but wouldn’t for a very long time because he was utterly terrified of the results if they were positive. It took us six months to get him to go (and he was negative in the end) but the getting him there was the worst bit.
Maybe if you have a talk with your boyfriend and aknowledge that he might be afraid of it being positive. Don’t use threats, don’t be angry. Explain how frustrating it is for you to have to deal with someone who is refusing to protect you. Explain to him that if he cares for your safety… he should go with you and do it. Tell him that you understand that he’s afraid that it might be positive, but tell him that it probably won’t be. This is just a ‘just-in-case’ kind of test. Tell him that you trust him, but you just have to be sure. Explain that you’ll be there with him the whole time, and if its positive… you’ll help him. There’s a good chance that he’s terrified that you’ll walk out on him if you find out that he’s ‘defective’.
There’s a very good chance that he is in denial and doesn’t want to get tested because it will knock him out of that safety zone of dissasociation. Ignoring it doesn’t work, though. Troubles will come back ten times stronger and harder than they were the first time.
Make him feel truly safe with you. Comfort him. This is something that is hard for everyone. Imagine if you had to take a pregnancy test and were absolutely terrified that it was going to come out positive.
Help him with his fears and not only will your relationship expand, but you will probably be able to get him in.