Chapter 8 Testing the Programs

Chapter 8 Learning Objectives Be able to …  Define different types of faults and how to classify them  Define the purpose of testing

Discussion Questions  What are some different types of program faults?  What is the difference between a program fault versus a program failure?

Discussion Questions  Why do we test for program faults?  Who does the testing?

Chapter 8 Learning Objectives Be able to …  Describe unit testing  Describe integration testing  Explain the difference between them

Unit Testing  unit testing is a procedure used to validate that individual units of source code are working properly  A unit is the smallest testable part of an application In procedural programming a unit is a function, procedure, subroutine, etc. In object-oriented programming, a unit is a method  The goal is to show that the individual parts are correct

Integration Testing Top-down testing Bottom-up testing Sandwich testing Big-bang testing

Discussion Question What are some differences between integration testing of object-oriented programs versus procedural programs?

OO Integration Testing Strategies  Thread-based testing: integrates classes required to respond to event  Use-based testing: integrates classes required by one use case  Cluster testing: integrates classes required to demonstrate one collaboration

Discussion Question  How do we know when we can stop testing?

Unit Testing with xUnit  Test fixture : a class that contains one or more test methods  Test method : a method that executes a specific test  Test runner : an application that finds and executes test methods on test fixtures  Assertion : a Boolean expression that describes what must be true when some action has been executed

public class Account { private double balance = 0.0; public Account(double b) { balance = b; } public double Balance { get { return balance; } } public void Withdraw(double amount) { if (balance >= amount) balance -= amount; } public void Deposit(double amount) { // TO DO } Class to be unit tested

[TestClass()] public class AccountTest {... [TestMethod()] public void WithdrawTestWithSufficientFunds() { Account acct = new Account(100.0); acct.Withdraw(50.00); Assert.AreEqual(50.0, acct.Balance); } [TestMethod()] public void WithdrawTestWithInsufficientFunds() { Account acct = new Account(100.0); acct.Withdraw(150.00); Assert.AreEqual(100.0, acct.Balance); } Test Fixture

Test Runner

Test-Driven Development  Never write a single line of code unless you have a failing automated test  Refactor to eliminate duplication

Red/Green/Refactor 1.Write the test code 2.Compile the test code (It should fail because you haven’t implemented anything yet.) 3.Implement just enough to compile. 4.Run the test and see it fail. 5.Implement just enough to make the test pass. 6.Run the test and see it pass. 7.Refactor for clarity and to eliminate duplication. 8.Repeat from the top.