White box testing. White-box testing. Types of WBT 24/03/15. Advanced Programming

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1 White box testing Advanced Programming 24/03/15 Barbara Russo 1 White-box testing White-box testing is a verification technique software engineers can use to examine if their code works as expected 24/03/15 Barbara Russo 2 Types of WBT Unit testing (we focus on unit testing in the following) Regression testing Integration testing 24/03/15 Barbara Russo 3 1

2 WBT with unit testing Each time you write a code module, you should write test cases for it A possible exception to this recommendation is the accessor methods (i.e., getters and setters) of your projects You should concentrate your testing effort on code that could easily be broken Generally, accessor methods will be written error-free 24/03/15 Barbara Russo 4 Scaffolding Scaffolding is method for unit testing It uses Drivers Stubs Harnesses Oracles 24/03/15 Barbara Russo 5 Driver Driver: is a software module used to invoke a module under test and, often, provide test inputs, control and monitor execution, and report test results line of code that calls a method and passes that method a value 24/03/15 Barbara Russo 6 2

3 Example of driver moveplayer(player1, 2); call a method moveplayer and passes player1 and moves it two spaces The drivers would likely to be called from main method A white-box test case would execute this driver line of code and check Player.getPosition() to make sure the player is now on the expected cell on the chess board 24/03/15 Barbara Russo 7 Stub A stub is a computer program statement substituting for the body of a software module that is or will be defined elsewhere or A dummy component or object used to simulate the behaviour of a real component until that component has been developed 24/03/15 Barbara Russo 8 Examples of stub Simply: public void moveplayer(player aplayer, int dicevalue) { or public void moveplayer(player aplayer, int dicevalue) { player=aplayer; player.setposition(1); 24/03/15 Barbara Russo 9 3

4 WBT with drivers and stubs Developing stubs allows programmers to call a method in the code being developed, even if the method does not yet have the desired behaviour Stubs can be filled in later to form the actual method 24/03/15 Barbara Russo 10 Oracle An oracle is a piece of code that compares the output of a driver with the a predicted output In JUnit these are assert methods: assertequals(predicted output, output of a driver) 24/03/15 Barbara Russo 11 Harness It is the environment in which to execute the tests Typically are frameworks Example: JUnit library for eclipse 24/03/15 Barbara Russo 12 4

5 What are drivers, stubs, and oracles? public void testcenterline() { Formatter f = new Formatter(); f.setlinewidth(10); assertequals(" word ", f.center("word")); public void testoddcenterline(){ Formatter f = new Formatter(); f.setlinewidth(10); assertequals( " hello ", f.center("hello")); public String center(string line) { return a ; 24/03/15 Barbara Russo 13! What are drivers, stubs, and oracles? public void testcenterline() { Formatter f = new Formatter(); f.setlinewidth(10); assertequals(" word ", f.center("word")); public void testoddcenterline(){ Formatter f = new Formatter(); f.setlinewidth(10); assertequals( " hello ", f.center("hello")); public String center(string line) { return a ; 24/03/15 Barbara Russo 14! TESTING WITH JUNIT 4/2/14 Barbara Russo 15 5

6 Installing JUnit Download from the jar file Unzip or import the jar file Add to classpath of your project Project à Properties à Java Build Path Libraries tab Add library 16 Installing JUnit Right click on the project folder in package explorer BuildPath à add Libraries tab Or BuildPath à in the library tab select add library The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. 6

7 TestCase in JUnit Any class that contains test methods should subclass the TestCase class testxxx() methods are defined in this class When you want to check the expected and actual test results, you invoke assert() and pass a boolean expression which will indicate if the test case is passed or not 19 TestCase in JUnit Fixtures: When a test class contains multiple testxxx() methods, you can use the setup() and teardown() methods to initialize and release any common objects under test 20 Writing a Test Case (1/2) A. Import the Junit harness: import junit.framework.*; B. Define a subclass of TestCase C. Override the setup() method to initialize object(s) under test (optional) D. Override the teardown() method to release any permanent resources you allocated in setup() (optional) 21 7

8 Writing a Test Case (2/2) D. Define one or more testxxx() methods that exercise the objects under test E. Define a suite() method that creates a TestSuite containing all the testxxxx() methods of a TestCase F. Define a main() method that runs the TestCase 22 Let s see the JUnit code Main classes junit.framework.testcase junit.framework.testsuite junit.textui.testrunner junit.ui.testrunner junit.ui.loadingtestrunner 4/2/14 Let s see the JUnit code Steps: Subclass TestCase Write test cases, methods that start with test setup() - initialize variables teardown() - release resources, reset use a TestRunner to run tests Example in the shell java junit.ui.loadingtestrunner TestClass org.junit.runner.junitcore.runclasses(testclass1.class,...); or java org.junit.runner.junitcore TestClass1 [...other test classes...] TestRunner expects the name of a TestCase class as argument. 24 8

9 Let s see the JUnit code 25 TestSuite TestCase instances can be composed into TestSuite hierarchies that automatically invoke all the testxxxx() methods defined in each TestCase instance A TestSuite is a composite of: Other tests TestCase instances (using addtest() ) Other TestSuite instances (using addtest() ) 26 Organizing Tests Create test cases in the same or a lateral package as the code under test Has all the application level classes and test cases for those components For each Java package, define a TestSuite class that contains all the test for verifying code in the package 27 9

10 Example the class import java.util.*; public class BrowsableList { private Vector items; public BrowsableList() { items = new Vector(); public void add(browsable element) { items.add(element); 28 Example the class public Browsable first() throws NoSuchElementException{ return (Browsable) items.firstelement(); public Browsable removefirst() throws NoSuchElementException { try { return (Browsable) items.remove(0); catch (ArrayIndexOutOfBoundsException e) { throw new NoSuchElementException("no elem!"); public boolean isempty() {return items.isempty(); 29 Example the test class import junit.framework.*; import junit.textui.*; public class BrowsableListTest extends TestCase { public static void main(string[] args) { // run the test from the main of JUnitCore in the package runner org.junit.runner.junitcore.main(browsablelist.class.getname()); private BrowsableList items; private TestItem alpha; private TestItem beta; public void setup() { items = new BrowsableList(); alpha = new TestItem("alpha"); beta = new TestItem("beta"); 30 10

11 Example the test class public void teardown() { public BrowsableListTest() { super(""); public BrowsableListTest(String name) { super(name); public void testisempty() { assert(items.isempty()); public void testaddoneelement() { items.add(alpha); Browsable first = items.first(); TestItem expected = new TestItem("alpha"); assertequals(first, expected); assert(!items.isempty()); 31 Example the test class public void testaddtwoelements() { items.add(alpha); items.add(beta); Browsable first = items.removefirst(); TestItem expectedalpha=new TestItem("alpha"); Browsable second = items.removefirst(); TestItem expectedbeta = new TestItem("beta"); assertequals(first, expectedalpha); assertequals(second, expectedbeta); assert(items.isempty()); public static Test suite() { return new TestSuite(BrowsableListTest.class); 32 Simple Test Suite package junit.samples; import junit.framework.test; import junit.framework.testcase; import junit.framework.testsuite; /* Some simple tests. */ public class SimpleTest extends TestCase { protected int fvalue1; protected int protected void setup() { fvalue1= 2; fvalue2= 3; public static Test suite() { /* the dynamic way */ return new TestSuite(SimpleTest.class); 11

12 Simple Test Suite public void testadd() { double result= fvalue1 + fvalue2; // forced failure result == 5 asserttrue(result == 6); public void testdividebyzero() { int zero= 0; int result= 8/zero; result++; public void testequals() { assertequals(12, 12); assertequals(12l, 12L); assertequals(new Long(12), new Long(12)); assertequals("size", 12, 13); assertequals("capacity", 12.0, 11.99, 0.0); public static void main (String[] args) { junit.textui.testrunner.run(suite()); 24/03/15 Barbara Russo 34 Setting up Composite Test Suites package junit.samples; import junit.framework.test; import junit.framework.testsuite; /* TestSuite that runs all the sample tests */ public class AllTests { public static void main (String[] args) { junit.textui.testrunner.run(suite()); public static Test suite( ) { TestSuite suite= new TestSuite("All JUnit Tests"); suite.addtest(simpletest.suite()); suite.addtest(new TestSuite(junit.samples.money.MoneyTest.class)); suite.addtest(junit.tests.alltests.suite()); return suite; Runnig a test with annotation When a class is annotated or extends a class annotated JUnit will invoke the class it references to run the tests in that class instead of the runner built into Junit 24/03/15 Barbara Russo 36 12

13 The test suite class Public class AllTest{ import org.junit.runner.runwith; import org.junit.runners.suite; BTest.class, CTest.class) public class ABCSuite { 24/03/15 Barbara Russo 37 Create the test source folder 24/03/15 Barbara Russo 38 The JUnit Build Path 24/03/15 Barbara Russo 39 13

14 Selecting the class and the method 24/03/15 Barbara Russo 40 Creating the test suite 24/03/15 Barbara Russo 41 Run the test 24/03/15 Barbara Russo 42 14

15 Test Output 24/03/15 Barbara Russo 43 JUnit Testing tips If you find yourself debugging using System.out.println(), write a test case instead if possible When a bug is reported, write a test case to expose the bug Don t deliver code that doesn t pass all the tests Write test cases to ensure method, statement, condition coverage if possible 44 15