Sardine storecupboard spaghetti

Name: Sardine storecupboard spaghetti
Ingredients: 100g spaghetti; 1 tbsp olive oil; 1 small onion, finely chopped; 2 large garlic cloves, finely chopped; 10 cherry tomatoes, halved; 95g can boneless sardine in olive oil, drained; 8 green pitted olives, halved; 2 tsp caper; handful parsley leaves, chopped