prolog predefined lists search

Question

I'm new to and just started writing prolog code I'm not sure how list of lists works and how to write rules for already defined lists, when I enter run_tests. below test cases should be executing

Below is the project I am working on, could anyone help me getting started on this?

employees([ employee(tom, 33, cs, 85000.00),
        employee(joan, 23, ece, 110000.00),
        employee(bill, 29, cs, 69500.00),
        employee(john, 28, me, 58200.00),
        employee(sue, 19, cs, 22000.00)
      ]).


dept_employees(Employees, Dept, DeptEmployees) :-
    'TODO'(Employees, Dept, DeptEmployees).


:- begin_tests(dept_employees, []).
test(dept_employees_cs, all(Zs =
                [[ employee(tom, 33, cs, 85000.00),
                  employee(bill, 29, cs, 69500.00),
                  employee(sue, 19, cs, 22000.00)
                ]])) :-
    employees(E),
    dept_employees(E, cs, Zs).

test(dept_employees_ece, all(Zs = [[ employee(joan, 23, ece, 110000.00) ]])) :-
    employees(E),
    dept_employees(E, ece, Zs).

test(dept_employees_ce, all(Zs = [[]])) :-
    employees(E),
    dept_employees(E, ce, Zs).
:- end_tests(dept_employees).