CMPUT 301 - Class Participation Exercise 10

Class Participation Exercise 10

Class Participation Exercise 10

Proper completion of this exercise is considered as part of course participation. An answer will be discussed in class.

You want a GPS device to disable itself temporarily if it detects it is going faster than 200 km/h. Write the code for a mock object (class MockLocation) that will allow running of bolded lines of class PersonTracker in method testTooFast of class TestPersonTracker.

class PersonTracker {
    ...
    Location lastLocation = null;

    // called every second
    void updateLocation( Location l ) throws GPSException {
        if (lastLocation != null) {
            if (lastLocation.distance( l ) > 200.0*1000/3600) {
                // 200 km/h in m/s
                GPS.getGPS().disable( 200 );
                throw new GPSException( "Too Fast!" );
            }
        }
        lastLocation = l;
    }
}

interface Location {
    // distance in metres
    public double distance( Location l );
}

class TestPersonTracker extends TestCase {
    void testTooFast() {
        PersonTracker p = new PersonTracker();
        Location l = new MockLocation( 0, 0 );
        try {
            p.updateLocation( l );
            p.updateLocation( l );
            fail( "This was supposed to throw exception." );
        } catch (GPSException e) {
            return; // exception was properly thrown
        }
    }
}

State any assumptions. You should try to avoid modifying the given code.

Submit your Java code in a zip file.