public void TestToString()
{
string representation = "!(A->B|C&D)";
Formula f = Formula.Parse(representation);
Assert.IsTrue(f.ToString() == representation);
representation = "(A->B)->(A->B&C)->D|F";
f = Formula.Parse(representation);
Assert.IsTrue(f.ToString() == representation);
f = new Assumption(new List<string> {"A", "B&C"}.Select(Formula.Parse).ToList(), Formula.Parse("A->B&C"));
Assert.IsTrue(f.ToString() == "A, B&C|-A->B&C");
}