public void GetAllEmployees_5NestedEmployees_5Employees()
        {
            // Arrange
            var hireDate = DateTime.Today;
            var james    = new Salesman("James", hireDate);

            var john = new Manager("John", hireDate);

            james.AddSubordinate(john);

            var jack = new Salesman("Jack", hireDate);

            john.AddSubordinate(jack);

            var jo = new Manager("Jo", hireDate);

            jack.AddSubordinate(jo);

            var jon = new Manager("Jon", hireDate);

            jo.AddSubordinate(jon);

            var jastin = new Employee("Jastin", hireDate);

            jo.AddSubordinate(jastin);

            // Act
            var count = james.GetAllEmployees().Count();

            // Assert
            Assert.AreEqual(5, count);
        }
        public void GetAllEmployees_3NestedEmployees_3Employees()
        {
            var count = salesman.GetAllEmployees().Count();

            Assert.AreEqual(3, count);
        }