public void EqualsTest1() { Variable x1 = "x"; Number num1 = 2; Mul mul1 = new Mul(num1, x1); Abs abs1 = new Abs(mul1); Variable x2 = "x"; Number num2 = 2; Mul mul2 = new Mul(num2, x2); Abs abs2 = new Abs(mul2); Assert.IsTrue(abs1.Equals(abs2)); Assert.IsTrue(abs1.Equals(abs1)); }