// Validate the child employee objects of a department object
private static void assertDepartment(Department department, Employee... employees) {
Assert.assertEquals(employees.length, department.getEmployees().size());
if (employees.length != 0) {
Set<Employee> set = new HashSet<>((employees.length * 4 + 2) / 3);
for (Employee employee : employees) {
set.add(employee);
}
Assert.assertEquals(department.getEmployees(), set);
}
}
@Test
public void test() {
/*
* Prepare two departments and 4 employees
*/
Department department1 = new Department();
Department department2 = new Department();
Employee employee1 = new Employee("E-1");
Employee employee2 = new Employee("E-2");
Employee employee3 = new Employee("E-3");
Employee employee4 = new Employee("E-4");
{
/*
* Validate the initialized state of these objects
*/
assertDepartment(department1);
assertDepartment(department2);
assertEmployee(employee1, null);
assertEmployee(employee2, null);
assertEmployee(employee3, null);
assertEmployee(employee4, null);
}
{
/*
* Add employee1 into department1.
* The property "department" of employee1 will be changed automatically and implicitly.
*/
department1.getEmployees().add(employee1);
assertDepartment(department1, employee1); // Changed by you
assertDepartment(department2);
assertEmployee(employee1, department1); // Changed automatically
assertEmployee(employee2, null);
assertEmployee(employee3, null);
assertEmployee(employee4, null);
}
{
/*
* Set department1 to be the parent of employe2.
* The property "employees" of department1 will be changed automatically and implicitly.
*/
employee2.setDepartment(department1);
assertDepartment(department1, employee1, employee2); // Changed automatically
assertDepartment(department2);
assertEmployee(employee1, department1);
assertEmployee(employee2, department1); // Changed by you
assertEmployee(employee3, null);
assertEmployee(employee4, null);
}
{
/*
* Add employee3 and employee4 into department1.
* (1) The property "department" of employee3 or employee4 will be changed automatically and implicitly.
*/
department1.getEmployees().addAll(MACollections.wrap(employee3, employee4));
assertDepartment(department1, employee1, employee2, employee3, employee4); // Changed by you
assertDepartment(department2);
assertEmployee(employee1, department1);
assertEmployee(employee2, department1);
assertEmployee(employee3, department1); // Changed automatically
assertEmployee(employee4, department1); // Changed automatically
}
{
/*
* Change the parent object of employee4 to be department2.
* (1) The property "employees" of the old parent object department1 will be changed automatically and implicitly.
* (2) The property "employees" of the new parent object department2 will be changed automatically and implicitly.
*/
employee4.setDepartment(department2);
assertDepartment(department1, employee1, employee2, employee3); // Changed automatically
assertDepartment(department2, employee4); // Changed automatically
assertEmployee(employee1, department1);
assertEmployee(employee2, department1);
assertEmployee(employee3, department1);
assertEmployee(employee4, department2); // Changed by you
}
{
/*
* Let department2 seize all the employees of department1
* (1) The property "department" of employee1, employee2 and employee3
* will be changed automatically and implicitly.
* (2) The original parent object department1 of employee1, employee2 and employee3 lost all the employees,
* so its property "employees" will be clean automatically and implicitly.
*/
department2.getEmployees().addAll(department1.getEmployees());
assertDepartment(department1); // Changed automatically
assertDepartment(department2, employee1, employee2, employee3, employee4); // Changed by you
assertEmployee(employee1, department2); // Changed automatically
assertEmployee(employee2, department2); // Changed automatically
assertEmployee(employee3, department2); // Changed automatically
assertEmployee(employee4, department2);
}
{
/*
* Advance functionality:
* Remove all the employees whose name ends with even number,
* that means employee2 and employee4 will be removed.
* The property "department" of employee2 and employee4 will be changed to be null automatically and implicitly.
*/
Iterator<Employee> itr = department2.getEmployees().iterator();
while (itr.hasNext()) {
Employee employee = itr.next();
int number =
Integer.parseInt(employee.getName().substring(employee.getName().indexOf('-') + 1));
if (number % 2 == 0) {
itr.remove(); // Can ONLY invoke remove of iterator, can NOT invoke remove of collection
}
}
assertDepartment(department1);
assertDepartment(department2, employee1, employee3); // Changed by you
assertEmployee(employee1, department2);
assertEmployee(employee2, null); // Changed automatically
assertEmployee(employee3, department2);
assertEmployee(employee4, null); // Changed automatically
}
{
/*
* Change the property "department" of employee1 to be null.
* The property "employees" of the parent object department2 will be changed automatically and implicitly.
*/
employee1.setDepartment(null);
assertDepartment(department1);
assertDepartment(department2, employee3); // Changed automatically
assertEmployee(employee1, null); // Changed by you
assertEmployee(employee2, null);
assertEmployee(employee3, department2);
assertEmployee(employee4, null);
}
{
/*
* Clean the property "employees" of department2.
* The property "department" of employee3 that is the last child of department2
* will be changed automatically and implicitly.
*/
department2.getEmployees().clear();
assertDepartment(department1);
assertDepartment(department2); // Changed by you
assertEmployee(employee1, null);
assertEmployee(employee2, null);
assertEmployee(employee3, null); // Changed automatically
assertEmployee(employee4, null);
}
}