public void ParseAtom()
{
Parser parser = new Parser("ok.");
IExpression expression = parser.ParseExpression();
Assert.IsNotNull(expression);
Assert.IsInstanceOfType(expression, typeof(AtomExpression));
AtomExpression atomexpression = (AtomExpression)expression;
Assert.AreEqual("ok", atomexpression.Atom.Name);
Assert.IsNull(parser.ParseExpression());
}