JUnit: A Java Testing Framework for Test-Driven Development, Slides of Java Programming

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JUnit for Test Driven Development

What is Test Driven Development

& JUnit?

• Test driven development (TDD) is one of the most successful

productivity enhancing techniques used by many in eXtreme

Programming. TDD has three step: write test, write code &

refactor.

• JUnit is an open source Java testing framework used in TDD.

JUnit was originally written by Erich Gamma and Kent Beck. It

is an instance of the xUnit architecture for unit testing

frameworks.

Desgin of JUnit (2)

• The test class can use the setUp() and tearDown() methods

to initialize and release common objects under test, referred

to as the test fixture.

• TestCase instances can be composed into TestSuites that

can automatically invoke all the testXXX() in each TestCase

instance. TestSuite can also have other TestSuite instances

and this allows the test to run automatically and provide test

status.

How to install JUnit?

• First, download the latest version of JUnit from

http://www.junit.org (Note: Eclipse should

already have JUnit installed.)

• For installing JUnit on Windows:

• Unzip the junit.zip to %JUNIT_HOME%
• Add JUnit to classpath:
• set CLASSPATH=%JUNIT_HOME%\junit.jar

• For installing JUnit on UNIX:

How to write JUnit Test Case?

• To write a test case follows these steps:

– Define a subclass of TestCase.

– Overide the setUp() method to initialize objects

under test.

– Optionally overide tearDown() method to release

object under test.

– Define one or more public testXXX() methods

that exercise the objects under test.

Sample Test Case

import junit.framework.TestCase;

public class ShoppingCartTest extends TestCase {

private ShoppingCart cart; private Product book1; // Sets up the test fixture. //Called before every testcase method. protected void setUp() { cart = new ShoppingCart();

Sample Test Case (3)

public void testEmpty() { cart.empty(); assertEquals(0, cart.getItemCount()); }

...

};

How to write JUnit Test Suite?

• A TestSuite comprises of various TestCase

instances.

• To write a test suite follow these steps:

– Create a class that defines a static suite() factory

method which creates TestSuites for all tests.

– Optionally define a main() method that runs the

TestSuite in batch mode.

Sample Test Suite (2)

// Another example test suite of tests. suite.addTest(CreditCardTestSuite.suite());

// Add more tests here return suite;

}

//Runs the test suite using the textual runner.

public static void main(String[] args) {

junit.textui.TestRunner.run(suite());

}

How to Run JUnit tests?

• JUnit provides textual and graphical interface (GI) to run tests.

Both interface indicates how many tests were run, errors or

failures and test status, “OK” for textual and green bar in GI.

• For running tests from textual interface: java

junit.textui.TestRunner ShoppingCartTest

• For running tests from graphical interface: java

junit.swingui.TestRunner ShoppingCartTest

Why use JUnit?

• Its free!

• It is simple and elegant to use.

• It is easy and inexpensive to write tests using

the JUnit testing framework.

• JUnit tests checks their own result and provide

quick visual feedback.

• Tests can be composed into TestSuites.

• It is integrated into IDE’s like Eclipse and

NetBeans.