@Test public void testDataServiceCanFetchProducts() throws Exception { assertFalse(service.getAllProducts().isEmpty()); }
public abstract Collection<Product> getAllProducts();
DataService { public abstract Collection<Product> getAllProducts(); }
DataService { public abstract Collection<Product> getAllProducts();  }
DataService { public abstract Collection<Product> getAllProducts();  abstract Collection<Product> getAllProducts(); abstract Collection<Category> getAllCategories(); abstract void updateProduct(Product p); abstract void deleteProduct(int productId); abstract Product getProductById(int productId); static DataService get(); }
DataService { public abstract Collection<Product> getAllProducts();  abstract Collection<Product> getAllProducts(); abstract Collection<Category> getAllCategories(); abstract void updateProduct(Product p); abstract void deleteProduct(int productId); abstract Product getProductById(int productId); static DataService get();  }