1 CSC 216 Lecture 3

2 Unit Testing  The most basic kind of testing is called unit testing  Why is it called “unit” testing?  When should tests be written? When  Before the code for a class is written.  After the code for a class is written, but before other classes are written.  After code for all classes is written, but before the classes are integrated.  After the classes are integrated.  The most basic kind of testing is called unit testing  Why is it called “unit” testing?  When should tests be written? When  Before the code for a class is written.  After the code for a class is written, but before other classes are written.  After code for all classes is written, but before the classes are integrated.  After the classes are integrated.

3 Testing at the Boundaries  What does this mean?  Example (from Dr. Jo Perry) For a method that removes an element from a list  Test on a list with 1 element  Test on a list that does not contain the element to be removed  Test on a list where the element is at the beginning/end of the list  Test on a list where the element appears multiple times  Test on an empty list  What does this mean?  Example (from Dr. Jo Perry) For a method that removes an element from a list  Test on a list with 1 element  Test on a list that does not contain the element to be removed  Test on a list where the element is at the beginning/end of the list  Test on a list where the element appears multiple times  Test on an empty list

4 Testing a Square-Root Routine From the text: What kinds of tests were proposed?  Test numbers greater than 1.  Test numbers less than 1.  Test negative numbers.  Test randomly generated numbers.  Apply the inverse of the square-root operation. From the text: What kinds of tests were proposed?  Test numbers greater than 1.  Test numbers less than 1.  Test negative numbers.  Test randomly generated numbers.  Apply the inverse of the square-root operation.

5 Testing a Stack  Suppose we have a MyStack class implemented in an integer array.  MyStack(int n);  void push(int i);  int pop();  int top();  Suppose we have a MyStack class implemented in an integer array.  MyStack(int n);  void push(int i);  int pop();  int top();

6 Testing a Stack  Suppose we have a MyStack class implemented in an integer array.  MyStack(int n);  void push(int i);  int pop();  int top();  Suppose we have a MyStack class implemented in an integer array.  MyStack(int n);  void push(int i);  int pop();  int top();

7 Testing a Stack  Suppose we have a MyStack class implemented in an integer array.  MyStack(int n);  void push(int i);  int pop();  int top();  Suppose we have a MyStack class implemented in an integer array.  MyStack(int n);  void push(int i);  int pop();  int top(); 17 9

8 Testing a Stack  Suppose we have a MyStack class implemented in an integer array.  MyStack(int n);  void push(int i);  int pop();  int top();  What test cases should we use? What test cases  Suppose we have a MyStack class implemented in an integer array.  MyStack(int n);  void push(int i);  int pop();  int top();  What test cases should we use? What test cases 17

9 What is JUnit?  An open-source regression-testing framework for Java  JUnit’s web site:  Eclipse includes JUnit  However, you need to set it up inside each project.  It allows you to define regression tests for your code and run them from the Java IDE.  An open-source regression-testing framework for Java  JUnit’s web site:  Eclipse includes JUnit  However, you need to set it up inside each project.  It allows you to define regression tests for your code and run them from the Java IDE.

10 Testing » JUnit Test Cases  JUnit Test Cases  Test case  Runs multiple tests  Implemented as subclass of TestCase  Define instance variables that store the state of the tests in the class  Initialize TestCase by overriding setUp method  Cleanup after test case is done by overriding tearDown method  The Test framework will invoke the setUp and tearDown methods.  JUnit Test Cases  Test case  Runs multiple tests  Implemented as subclass of TestCase  Define instance variables that store the state of the tests in the class  Initialize TestCase by overriding setUp method  Cleanup after test case is done by overriding tearDown method  The Test framework will invoke the setUp and tearDown methods.

11 Testing » Setting up JUnit  JUnit is in Eclipse by default, but needs to be applied to a project by performing a few actions.  First, right-click on the name of the package.  JUnit is in Eclipse by default, but needs to be applied to a project by performing a few actions.  First, right-click on the name of the package.

12  From the popup menu, select “Build Path”; then “Configure Build Path” Testing » Setting up JUnit, cont.

13  Then select “Add Library” and then “JUnit”. Testing » Setting up JUnit, cont.

14  Then, when asked which version, just click on “Finish”. Testing » Setting up JUnit, cont.

15 Testing » Creating JUnit Test Cases in Eclipse  Create a new package to contain your test case classes.  Add the JUnit JAR file to the project’s buildpath.  Create a new package to contain your test case classes.  Add the JUnit JAR file to the project’s buildpath.

16 Testing » Creating JUnit Test Cases in Eclipse  Select your testing package  From the context menu select New » JUnit Test Case. This opens the New JUnit Test Case Wizard.  Fill in the name of your test case in the Name field.  Select the method stubs that you want Eclipse to generate  This will create the corresponding class in your testing package  Select your testing package  From the context menu select New » JUnit Test Case. This opens the New JUnit Test Case Wizard.  Fill in the name of your test case in the Name field.  Select the method stubs that you want Eclipse to generate  This will create the corresponding class in your testing package

17 Testing » JUnit TestCase Template public class NewTestCase extends TestCase { public static void main(String[] args) { } public NewTestCase(String arg0) { super(arg0); } protected void setUp() throws Exception { super.setUp(); } protected void tearDown() throws Exception { super.tearDown(); } public class NewTestCase extends TestCase { public static void main(String[] args) { } public NewTestCase(String arg0) { super(arg0); } protected void setUp() throws Exception { super.setUp(); } protected void tearDown() throws Exception { super.tearDown(); }

18 Testing » Adding Tests to Test Cases  Any method in a TestCase class is considered a test if it begins with the word “test”.  You can write many tests (have many test methods)  Each test method should use a variety of assert … methods to perform tests on the state of its class.  Any method in a TestCase class is considered a test if it begins with the word “test”.  You can write many tests (have many test methods)  Each test method should use a variety of assert … methods to perform tests on the state of its class.

19 Testing » JUnit Assert Methods  Assert methods include:  assertTrue(boolean)  assertFalse(boolean)  assertNull(object)  assertNotNull(object)  assertEquals(x,y)  assertSame(firstObject, secondObj)  assertNotSame(firstObject, secondObj)  Assert methods include:  assertTrue(boolean)  assertFalse(boolean)  assertNull(object)  assertNotNull(object)  assertEquals(x,y)  assertSame(firstObject, secondObj)  assertNotSame(firstObject, secondObj)

20 Testing » Example of a Test Case package stackTests; import junit.framework.TestCase; import stack.MyStack; public class Tests extends TestCase { protected void setUp() throws Exception { super.setUp(); } protected void tearDown() throws Exception { super.tearDown(); } public void testPush() { MyStack = new MyStack(5); m.push(27); assertEquals(m.pop(), 27); } package stackTests; import junit.framework.TestCase; import stack.MyStack; public class Tests extends TestCase { protected void setUp() throws Exception { super.setUp(); } protected void tearDown() throws Exception { super.tearDown(); } public void testPush() { MyStack = new MyStack(5); m.push(27); assertEquals(m.pop(), 27); }

21 Testing » Running JUnit Test Case  Select TestCase class  From the Run menu select Run » Run As » JUnit Test  This will run the tests in your TestCase class along with the setUp and tearDown methods  You will then get a report in the JUnit window  Select TestCase class  From the Run menu select Run » Run As » JUnit Test  This will run the tests in your TestCase class along with the setUp and tearDown methods  You will then get a report in the JUnit window

22 Testing » JUnit Window  Red indicates a test has failed  You can see which test failed  You can see the call trace leading to the failure  Red indicates a test has failed  You can see which test failed  You can see the call trace leading to the failure

23 Testing » JUnit Window  You can see how many tests ran  How many failures occurred  You can see the details of the failure  Errors occur when exceptions are thrown (e.g., when assertions fail)  You can see how many tests ran  How many failures occurred  You can see the details of the failure  Errors occur when exceptions are thrown (e.g., when assertions fail)

24 Testing » Exercise  Go through the Stack class and add additional unit tests.  The stack class is at  /csc216/lec/001/exercises/stack.java /csc216/lec/001/exercises/stack.java  Submit one of your test cases here. Submit one  Go through the Stack class and add additional unit tests.  The stack class is at  /csc216/lec/001/exercises/stack.java /csc216/lec/001/exercises/stack.java  Submit one of your test cases here. Submit one

25 Important terms  Black-box testing  White-box testing  Regression testing  Test coverage  Black-box testing  White-box testing  Regression testing  Test coverage