Access a List in JUnit Test Case

Question

I have this ParkingLot.java

 public class ParkingLot {

private final int size;
private Car[] slots = null;

List<String> list = new ArrayList<String>();

public ParkingLot(int size) {
    this.size = size;
    this.slots = new Car[size];
}

public List licenseWithAParticularColour(String colour) {
    for (int i = 0; i < slots.length; i++) {
        if (slots[i].getColour() == colour) {
            System.out.println(slots[i].getLicense());
            list.add(slots[i].getLicense());
            return list;
        }
    }
    return null;
}

}

I have created a ParkingLotTest.java as follows

public class ParkingLotTest {

private Car car1;
private Car car2;
private Car car3;

private Ticket ticket1;
private Ticket ticket2;
private Ticket ticket3;

private ParkingLot parkingLot;

private List<String> list = new ArrayList<String>();

@Before
public void intializeTestEnvironment() throws Exception {
    this.car1 = new Car("1234", "White");
    this.car2 = new Car("4567", "Black");
    this.car3 = new Car("0000", "Red");

    this.parkingLot = new ParkingLot(2);

    this.ticket1 = parkingLot.park(car1);
    this.ticket2 = parkingLot.park(car2);
    this.ticket3 = parkingLot.park(car3);
    this.list = parkingLot.list;


}

@Test
public void shouldGetLicensesWithAParticularColour() throws Exception {
    assertEquals(, parkingLot.licenseWithAParticularColour("White"));

}

}

In the above Test Case, I want to check that the List is filled with the correct Licenses. 1. How do i create a field in the ParkingLotTest.java so that the List in the first class is same as list in the second class file.

Answer 1

First, I don't think you need a list on ParkingLot so your question actually doesn't make much sense :)

Second, just set up the expected result in each test method:

public class ParkingLotTest {

    //...

    @Test
    public void shouldGetLicensesWithAParticularColour() throws Exception {
        List<Car> expected = new ArrayList<Car>();
        expected.add(...);

        assertEquals(expected, parkingLot.licenseWithAParticularColour("White"));
    }

}

And don't forget to also test unexpected values or special cases. For example:

@Test
public void shouldNotGetLicensesWithANullColour() throws Exception {
    ...
    assertEquals(expected, parkingLot.licenseWithAParticularColour(null));
}

@Test
public void shouldNotGetLicensesWithAnUnknownColour() throws Exception {
    ...
    assertEquals(expected, parkingLot.licenseWithAParticularColour("unknown"));
}

Some additional remarks:

• I wouldn't use a Car[] for the slots but a List<Car>.
• You don't really need the List<String> list in ParkingLot (and the current implementation of licenseWithAParticularColour is buggy).
• I would use an Enum for the color.