Unit tests in Visual Studio 2015 RC can not run

I created a unit project (windows 10 universal) and when I run a test method like:

[TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void TestMethod1()
        {
            int x = 1;
            Assert.AreEqual(1, x);
        }

    }

The test will not run: