public void BindProduct_ShouldReturnTrue_WhenParentProductExists() { //Arrange var productId = Guid.NewGuid(); var productTitle = "Mobile Phone"; var productDto = new ProductModel { Id = productId, Title = productTitle }; ProductOperations.ProductList.Add(productDto); var categoryId = Guid.NewGuid(); var categoryTitle = "Technology"; var categoryDto = new CategoryModel { Id = categoryId, Title = categoryTitle, ParentCategory = new CategoryModel() }; ProductOperations.ProductList.Add(productDto); //Act var result = _productOperations.BindCategory(productId, categoryDto); //Assert Assert.True(result); }