In a saucepan, heat the olive oil. Saute the garlic and add the sausages and rosemary. Cook for a few minutes, turning the sausages over. Pierce the sausages to allow the fat to drip out and flavor up the dish. Add the tomatoes to the pan. With the back of a wooden spoon, break up the tomatoes into little chunks. Add 1/2 a cup of water and allow to simmer. Then add the beans, salt, and pepper.
Let cook together for about 15 minutes or until the sauce has reduced and thickened.