public async void CanAddCartToUser()
{
DbContextOptions <StoreDbContext> options = new DbContextOptionsBuilder <StoreDbContext>()
.UseInMemoryDatabase("CanAddCartToUserTest")
.Options;
using (StoreDbContext cartContext = new StoreDbContext(options))
{
CartService cs = new CartService(cartContext);
Cart addedCart = await cs.AddCartToUser("1");
var result = await cs.GetCartByUserID("1");
Assert.Equal("1", result.UserId);
};
}