CSC 216/001 Lecture 4

Unit Testing  Why is it called “unit” testing?  When should tests be written?  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.  Why is it called “unit” testing?  When should tests be written?  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.

Testing at the Boundaries  What does this mean?  Example (from the online notes):  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 the online notes):  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.

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.

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? (Discuss in groups.)  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? (Discuss in groups.)

What is JUnit?  Regression testing framework  Written by Erich Gamma and Kent Beck  Used for unit testing in Java  Open Source  Released under IBM's CPL  Regression testing framework  Written by Erich Gamma and Kent Beck  Used for unit testing in Java  Open Source  Released under IBM's CPL

Testing » Where Does JUnit Come From?  JUnit’s web site:  Eclipse includes JUnit  Eclipse provides new GUI to run JUnit test cases and suites  JDT tools include a plug-in that integrates JUnit into the Java IDE  Allows you to define regression tests for your code and run them from the Java IDE.  JUnit’s web site:  Eclipse includes JUnit  Eclipse provides new GUI to run JUnit test cases and suites  JDT tools include a plug-in that integrates JUnit into the Java IDE  Allows you to define regression tests for your code and run them from the Java IDE.

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.

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.

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

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(); }

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.  Assert methods are inherited  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.  Assert methods are inherited

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

Testing » Adding Two Tests to JUnit Test Case 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 void testCompareSucceed() { assertEquals(0, 0); // this assertion will succeed } public void testCompareFail() { assertEquals(0, 1); // this assertion will fail } 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 void testCompareSucceed() { assertEquals(0, 0); // this assertion will succeed } public void testCompareFail() { assertEquals(0, 1); // this assertion will fail }

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

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  If you wish to see the tests in TestCase click on the Hierarchy tab  Red indicates a test has failed  You can see which test failed  You can see the call trace leading to the failure  If you wish to see the tests in TestCase click on the Hierarchy tab

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)