ClassicAssert.Null
ClassicAssert.Null and ClassicAssert.IsNull test that the specified object is null. The two forms are provided for compatibility with past versions of NUnit and NUnitLite.
ClassicAssert.Null(object anObject);
ClassicAssert.Null(object anObject, string message, params object[] params);
ClassicAssert.IsNull(object anObject);
ClassicAssert.IsNull(object anObject, string message, params object[] params);