1. CSIS 3701: Advanced Object Oriented Programming
Regression Testing
CSIS 3701: Advanced Object Oriented Programming

2. Class Drivers in Java public static void main(String[] args) {
Example: Simple driver for add method in NameList
public static void main(String[] args) {
NameList n = new NameList(3);
while(true) {
String name = JOptionPane.showInputDialog(null, "Enter name");
n.add(name);
JOptionPane.showMessageDialog(null, n.toString()); }

3. Class Drivers in Java public static void main(String[] args) {
May need additional code for exceptions
public static void main(String[] args) {
NameList n = new NameList(3);
while(true) {
String name = JOptionPane.showInputDialog(null, “Name:");
try {n.add(name);}
catch (FullListException ex) {
JOptionPane.showMessageDialog(null, "List full!"); }
catch (InListException ex) {
JOptionPane.showMessageDialog(null, “In list!");
JOptionPane.showMessageDialog(null, n.toString());

4. Regression Testing Problem: Fixing bugs can introduce other errors
10% to 20% of bug fixes create new bugs
Often happens as part of maintenance
Developer who changes one module not familiar with rest of system
Big problem: What if new bugs in code already tested?
Module A tested first
Fixing B creates bugs in A
If A not retested, will be shipped with bugs!
Module B tested second

5. Regression Testing
Regression testing: Retesting with all test cases after any change to code
Problem: May be thousands of tests!
Too many for interactive debugging
Comprehensive list of test cases
Fix bugs
Retest with all test cases
Find bugs

6. Automated Testing Goal: Automate comprehensive testing Approaches:
Run all test cases
Notify developer of incorrect results
Approaches:
Creating testing “script” in driver
Read test cases and desired results from file
Use testing tools (JUnit)

7. Scripted Testing For each constructor/void method: Execute method
Display value returned/exception thrown
Get current state to desired state (using toString() )
Display current state
Compare to desired state
Error message if incorrect
Display actual state

8. Scripted Testing Example
public static void main(String[] args) {
// Test default constructor
Clock c1 = new Clock();
if (!(c1.toString()).equals("00:00"))
System.out.println("Default constructor failure:" c1.toString());
// Test parameterized constructor
Clock c2 = new Clock(12,34);
if (!(c2.toString()).equals("12:34"))
System.out.println("Parameter constructor failure:" c2.toString());

9. Scripted Testing Example
// Test ability to set new time
c2.setTime(9,1);
if (!(c2.toString()).equals("09:01"))
System.out.println("setTime failure: "+c2.toString());
// Test ability of nextMinute to increment minute, hour
Clock c3 = new Clock(11, 59);
c3.nextMinute();
if (!(c3.toString()).equals("12:00"))
System.out.println("next failure: "+c3.toString());
Clock c4 = new Clock(23, 59);
c4.nextMinute();
if (!(c4.toString()).equals("00:00"))
System.out.println("next failure: "+c4.toString());

10. Scripted Testing for Inspectors
For each method that returns a value:
Execute method
Compare actual return value to desired value
Compare actual state to desired state
Make sure state not changed for inspectors
// Test getter inspectors, make sure state not changed
if (c2.getHour() != 9)
System.out.println("getHour failure: "+c2.getHour());
if (!(c2.toString()).equals("09:01"))
System.out.println("getHour changed state: " c2.toString());

11. Scripted testing for Validation
For each validation inspector:
Run test case to get value (true or false)
Compare to desired value
For each validation case in modifier:
Run test case
Make sure state not changed

12. Scripted Testing Example
// Test validation inspectors for border cases
if (c2.isHour(-1))
System.out.println("isHour failure: -1");
if (!c2.isHour(0))
System.out.println("isHour failure: 0");
if (c2.isHour(24))
System.out.println("isHour failure: 24");
if (!c2.isHour(23))
System.out.println("isHour failure: 23");

13. Scripted Testing Example
// Test validation in modifiers for no state change
c2.setTime(-1,12);
if (!(c2.toString()).equals("09:01"))
System.out.println("setTime validation failure: " c2.toString());
c2.setTime(24,12);
System.out.println("setTime validation failure: " c2.toString());