When people test positive for HIV, clinic workers already sit down with them and offer to help make up a list of names and contacts for last partners. The clinic will then call those people and tell them that someone they've had sexual contact with has been diagnosed as HIV+ and they need to come get tested. The bases are already covered.
It is already life altering to find out if you have tested positive. How horrible would it then be to have the clinic or a police offer sitting there while you have to contact your husband or wife and spill the beans as if you're some stupid little child that needs supervision.
You know, people who fight government expansion but are in this thread in favor of such a ridiculous law need to take a hard look in the mirror and see why their government keeps getting more powerful. They are against government expansion except, of course, in cases that they agree with it.
If the government must get involved in informing people in your life of your HIV+ status, then anonymous testing becomes obsolete, in which case many, many people will stop getting tested, myself included. I always use anonymous testing because I don't even want my family doctor having a record that I'm getting tested at all, regardless of what the result is. My sexual activities and status are nobody's damn business, and they're certainly not yours.
The overwhelming majority of HIV+ people would never want that horror inflicted on another person and so they take measures to not spread the disease. The overwhelming majority also tell partners they're involved with well before they both make the consensual choice to have sex, but that dialogue takes place when they are ready, and not when the law tells them to.
There are no barriers, financial or otherwise, to two consensual adults knowing their status in your country, so there is no excuse. A new law to baby people isn't necessary. People already have the power to know their own status and manage that knowledge in the context of a relationship.