The Code Coverage says something about the lines of program code that are covered by tests. Only a developer/tester can say something about how good these tests are.

As writer of the unit test and the code, it is imported to see how much of the code is hit by the unit tests.

Action Plan

Install the Emma Code Coverage Feature for Eclipse

• Use the Eclipse Marketplace to install the Code Coverage feature.

Run Code Coverage Check

• In the view Project Explorer or Package Explorer, go to the unit test classes.
• Use the context menu (on the RoomRepositoryTest): Coverage As > JUnit Test
  
  When the Coverage Run is finished, the view Coverage shows the percentages of code that are covered by a unit test.
  
  The class RoomRepository has a coverage of 71%, inspecting the related code, shows that there is no unit tests that covers the two exception cases, in the method public void add(final Room room)
  A good moment to add the missing unit tests

Adding missing Unit Test Cases

• Add these test to the class RoomRepositoryTest and fill in the details.

    @Test
    public void addNull() throws Exception {
        expExcep.expect(IllegalArgumentException.class);
        expExcep.expectMessage(new IsEqual<String>("Argument 'room' should not be null."));
        
        // TODO Fill in the test case details
    }

    @Test
    public void addWithSameLocation() throws Exception {
        expExcep.expect(IllegalArgumentException.class);
        expExcep.expectMessage(new IsEqual<String>("There is already a room registered with the location '01.12'."
                + " Registered room details 'Copenhagen, 01.12, 8, [ white board ]'"));

        // TODO Fill in the test case details
    }

• Probably the class Room is missing a nice output string and will show something like There is already a room registered with the location '01.12'. Registered room details 'com.github.verhagen.mrrs.domain.Room@40993028'.

• Creating a nice output text for an Object
  Override the method public String toString()

    @Override
    public String toString() {
        // TODO Fill in the details
    }

Discovering a Hidden Mistake

• After adding the missing test cases and writing a nice output for the class Room, let run again the Code Coverage, but now over all the classes.
• Select in the view Package Explorer or Project Explorer the project meeting-room-reservation-services.
• Use the context menu: Coverage As > JUnit Test
• Now the class RoomRepository should be 100% covered
• Not all src/main/java classes are 100% covered. Inspect the class Room.
  
  In the constructor of Room there is a check capacity <= 0, that is never hit with a value smaller or equal to 0. Therefore the background of the inner if statement is red. Looking opening the class RoomTest reveals that there is a test case for this situation.

    @Test(expected = IllegalArgumentException.class)
    public void createBasicRoomNegativeCapacity() throws Exception {
        String location = null;
        int capacity = -2;
        new Room(location, capacity);
    }

• Why is this not working as intended?
  TIP: Use the Eclipse debugger, to find out why this goes wrong.
• How to fix the issue?
• What improvement(s) do you see?

Is the Code Coverage now Up To Date ?

• Run the Code Coverage again over the hole code base (of the project meeting-room-reservation-services).
• Can the Code Coverage still be improved? (skip the class MyResource)