Long drives are only romantic in movies because when it comes to the real world, you and your partner can end up fighting over the radio station or the use of the air conditioner. Thus, road trips are the best way to test your relationship. You and your partner will have to spend a considerable amount of time together, which will give you an idea about whether or not the relationship can stand firm in the face of trouble.
The choice of television shows is another major test when it comes to knowing where the relationship stands. Little differences in these choices are tolerable, but a wide range of serious differences can become a problem in the future. Imagine yourself in a situation where you want to watch the biggest game of the season and your partner wants to watch some other show. This is going to trigger a stalemate which could in fact turn into a huge fight.
When one of you loses something valuable, this will either bring out the best in you or the worst. For instance if your partner has lost something precious and blames you for it, when you were not even involved in the matter, then this is a sign that you two will probably not go a long way as a couple. If you or your partner get angry, and are extremely difficult to handle just because you lost something, then the relationship needs some serious reconsideration.
You need to see if you two have the same values; it is very important that values match, as these make the relationship stable. Have a discussion about this, in order to test the relationship.
You need to observe how your partner behaves around your friends; if she/he is not friendly, chances are she/he will make you drift away from your old friends. For some, this is a major flaw in a relationship.