Write a simple implementation of our Order interface. Make the constructor of your new class take an OrderingSystem as a parameter in order to get a different order reference for each order.
A stub is provided (below) as an example of an ordering system: look at its code and observe that it is a singleton so that the method getUnusedOrderReference() avoids being static. A test class for the stub is also provided. Both the stub and its test would belong in the test/src directory - neither would be intended to become live code.
Fully unit test your booking class (100% coverage), mocking out all the other objects on which it depends.
----------------------------------------------------------
package net.grelf.course;
public abstract class OrderingSystem
{
public abstract String getUnusedOrderReference ();
} // OrderingSystem
----------------------------------------------------------
package net.grelf.course;
import java.util.HashMap;
import java.util.Map;
/** A proxy for the ordering system. Written as a singleton so that methods such as
* getUnusedOrderReference () can be non-static and therefore be mocked. */
public final class OrderingSystemStub extends OrderingSystem
{
private static final OrderingSystemStub INSTANCE = new OrderingSystemStub ();
private OrderingSystemStub () { /* Not to be available to anyone else */ }
public static OrderingSystemStub getInstance ()
{
return INSTANCE;
}
/** Not suitable for production code! */
@Override
public String getUnusedOrderReference ()
{
String ref;
final int MAX_COUNT = 100;
int count = 0;
do
{
ref = "";
count++;
for (int i = 0; i < 6; i++)
{
ref += (char) (26 * Math.random () + charBase);
}
}
while (null != usedReferences.get (ref) && count < MAX_COUNT);
usedReferences.put (ref, ref);
return ref;
} // getUnusedOrderReference
private static final int charBase = (int) 'A';
private static Map <String, String> usedReferences = new HashMap <String, String> ();
} // OrderingSystemStub
----------------------------------------------------------------
package net.grelf.course;
import static org.junit.Assert.*;
import org.junit.Test;
public class OrderingSystemStubTest
{
@Test
public void testGetInstance ()
{
assertNotNull (OrderingSystemStub.getInstance ());
}
/**
* Test method for {@link net.grelf.course.OrderingSystemStub#getUnusedOrderReference()}.
*/
@Test
public void testGetUnusedOrderReference ()
{
final int N_REFS = 3;
String [] refs = new String [N_REFS];
for (int refNo = 0; refNo < N_REFS; refNo++)
{
refs [refNo] = OrderingSystemStub.getInstance ().getUnusedOrderReference ();
assertEquals ("Unused order ref should have length 6", 6, refs [refNo].length ());
for (int i = 0; i < 6; i++)
{
assertTrue ("Unused order ref should only be upper case letters", Character.isUpperCase (refs [refNo].charAt (i)));
}
if (refNo > 0)
{
assertFalse ("Successive unused order refs should differ", refs [refNo].equals (refs [refNo - 1]));
}
}
}
} // OrderingSystemStubTest
------------------------------------------------------------