Classifier - Software Development Case Studies in Java - page 68

The TestTree test case checks the functionalities of the classes Node and
indirectly Arc .

public class TestTree extends TestCase {
public void testLeaf(){
String label # "leaf label";
Node leaf # new Node(label);
assertTrue("Should be a leaf",leaf.isLeaf());
assertEquals(label,leaf.label());

}
public void testOneLevel(){
Node leftLeaf # new Node("left");
Node rightLeaf # new Node("right");
String toLeft # "to the left";
String toRight # "to the right";
Node root # new Node("root");
root.addChild(toLeft,leftLeaf);
root.addChild(toRight,rightLeaf);
assertFalse("root shouldn't be a leaf", root.isLeaf());
assertSame(leftLeaf,root.follow(toLeft));
assertSame(rightLeaf,root.follow(toRight));

}

}
Finally the TestClassifier test case checks whether the classifier assigns the
category correctly to an item. To test this functionality, four main steps are
required:
■ define the type of item, i.e. its features;
■ build a decision tree;
■ apply it to some items;
■ check if the assigned categories are correct.
Given the classification tree shown in Figure 4.1, we have to define which
items will be used to test the classifier. Since the classification algorithm
follows a path through the decision tree, we will use items that force it to
traverse all the paths in the test tree. There are four possible paths in the
decision tree as described in Figure 4.1.
The TestClassifier test case has only one test method and a helper method
that builds the decision tree. The test method applies the classifier to the
four items described in Table 4.1.

Table 4.1 Test items
Item AC ABS Expected category

1 Yes Yes High

2 Yes No Medium

3 No Yes Medium

4 No No Low