Formatting strings - looks to be same between XAML and regular .NET code

gistfile1.cs

using System.Windows;
using System.Windows.Data;
using Xunit;

namespace ConsoleApplication2
{
    public class Test
    {
        DependencyObject dObj = new DependencyObject();

        [Fact]
        public void Using_Binding_Should_Round_Down()
        {
            // arrange
            double second = 127.533;
            var binding2 = new Binding { Source = second, StringFormat = "{0:0}" };
            var secondProperty = DependencyProperty.Register("Second", typeof(string), typeof(Program));
            BindingOperations.SetBinding(dObj, secondProperty, binding2);

            // act
            var oneTwoSeven = (string)dObj.GetValue(secondProperty);

            Assert.Equal("127", oneTwoSeven);
        }

        [Fact]
        public void Using_Defaults_Should_Round_Down()
        {
            // arrange
            double second = 127.533;

            // act
            var oneTwoSeven = second.ToString("0");

            Assert.Equal("127", oneTwoSeven);
        }
    }
}