ASP.net Core MVC testing / make controller return a string?

I'm currently at the point where I want to write a test for my ASP.net Core MVC project.

The problem is that I currently put this code into my view, which isn't really suitable for testing.

A snippet of the code is as follow:

@if (Model.MealDays != null)
{
    bool boolSaltLess = false;

        @foreach (var c in Model.MealDays)
        {
                @{
                    if (@c.Meal.Saltless == true)
                    {
                        boolSaltLess = true;
                    }
                }
        }
    <div>
        <p><b>Missing meal diets:</b></p>
        @if (boolSaltLess == false)
        {
            <p style="color:red">A saltless meal!</p>
        }
   </div>
}

My initial question is if I could move this code into my controller, and what result I would need to return from my controller to display this information in my View.