C# UnitTest - Assert.AreEqual() does not call Equals if the argument is null

using Microsoft.VisualStudio.TestTools.UnitTesting;

class TestClass
{
    public override bool Equals(object obj)
    {
    	return true;
    }
}

[TestMethod]
public void TestMethod1()
{
    TestClass t = new TestClass ();
    Assert.AreEqual (t, null); // fails
    Assert.IsTrue (t.Equals (null)); // passes
}