Unit Testing with JUnit

Dan FleckSpring 2010

What is Unit Testing?

A procedure to validate individual units of Source Code

Example: A procedure, method or class

Validating each individual piece reduces errors when integrating the pieces together later

Automated Unit Tests with JUnitJunit is a unit testing

framework for Java Allows you to write unit tests

in Java using a simple interface

Automated testing enables running and rerunning tests very easily and quickly

An example unit test

@Testpublic void testCellChangePropagates() {

Spreadsheet sheet = new Spreadsheet();

sheet.put("A1", "5"); sheet.put("A2", "=A1"); sheet.put("A1", "10");

assertEquals("10",sheet.get("A2")); }

Junit Assert During a test use Asserts to specify if the test passed or failed

org.junit.Assert – allows you to test if certain ideas hold by asserting results: http://junit.sourceforge.net/javadoc/

assertEquals(expected, actual) assertEquals(message, expected, actual) assertEquals(expected, actual, delta) assertEquals(message, expected, actual, delta) assertFalse(condition) assertFalse(message, condition) Assert(Not)Null(object) Assert(Not)Null(message, object) Assert(Not)Same(expected, actual) Assert(Not)Same(message, expected, actual) assertTrue(condition) assertTrue(message, condition)

Junit Methods – Java annotations @BeforeClass // Run before all tests in class public static void setUpClass() throws Exception {}

@AfterClass // Run after all tests in class public static void tearDownClass() throws Exception {}

@Before // Run before each test in class public void setUp() {}

@After // Run after each test in class public void tearDown() {}

@Test public void testMain() { http://www.cavdar.net/2008/07/21/junit-4-in-60-seconds/

Junit with Netbeans

1. New File2. Choose file type: Junit3. Choose Test for Existing Class4. Junit test with all stubs

created for that class5. Fill in the individual tests6. Run Tests (Netbeans options)

Note: If this option doesn’t exist use New File->Other->Junit->Test for existing class

Junit Documentation/Tutorials http://junit.sourceforge.net/

http://code.google.com/p/t2framework/wiki/JUnitQuickTutorial

http://junit.sourceforge.net/doc/testinfected/testing.htm (older)

Lines of code coverage analysis

Determining which lines of code your tests have exercised and which they have not

Allows you to detect if your unit tests (or system tests) are adequately covering all possibilities or not

This is just one way to test

Lines of code coverage analysis with Netbeans• Install Unit Test Code

Coverage Viewer module• (See next slide for instructions)

• Write a Unit Test• Run test and view highlighted

code

Installing the Code Coverage Plugin Go into Netbeans -> Tools -> Plugins

Search for "Code Coverage" and install it.

If you don't see it in the list of available plugins, go to the "Settings" tab and check "Netbeans Beta”, reload the catalog, and then try again.

If you don't see Netbeans Beta in the list on Settings, add the following source for plugins:

Netbeans Beta

http://updates.netbeans.org/netbeans/updates/6.8/uc/final/beta/catalog.xml.gz

How do you you combine coverage with traditional system test scripts? Traditional system testing uses scripts- 1. Enter salary- 2. Enter number of dependents- 3. Click “Calculate Taxes” button- …

To combine this with coverage, launch the GUI while capturing coverage statistics

Run the test case to determine coverage

How to write test cases

See sample system test case http://www.cs.gmu.edu/~kdobolyi/cs421/

SAMPLESystemTestCase.doc

See sample unit test case http://www.cs.gmu.edu/~kdobolyi/cs421/

Main.java http://www.cs.gmu.edu/~kdobolyi/cs421/

Triangle.java http://www.cs.gmu.edu/~kdobolyi/cs421/

Triangle.java

Class Exercise - Lets try it out! Using the

SystemRequirementsSpecificationExample.doc

Each team pick a use caseDocument the overall system

or unit tests you would write to test

Do the same for a non-functional requirement (sec 5)

Summary

Unit tests can help test the details of your program

Automated unit tests provide constant visibility and easy retesting

Test coverage supplies valuable information when running both unit tests and system tests