Cook the macaroni as directed on the package, until al dente. Drain and stir in a little oil or butter, to prevent the noodles from sticking. Set aside.

Add the sausage to a Dutch oven or stew pot, over medium heat. Cook for about 3 minutes, then stir in the onion. Cook for another 5 minutes, or until the onions are tender and the sausage has browned.

Stir in the tomatoes, beans and macaroni. Continue to cook for about 15 to 20 minutes, stirring occasionally. Season to taste with salt and pepper and serve.