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Re: [DotGNU]pnetlib::csunit

From: Sriram Karra
Subject: Re: [DotGNU]pnetlib::csunit
Date: 12 Apr 2002 18:48:50 +0530
User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.1

Rhys Weatherley <address@hidden> writes:

> S11001001 wrote:
> > Could Rhys or someone please post a quick HOWTO for writing
> > pnetlib unit tests?
> The "csunit" framework is a stripped-down version of JUnit/NUnit,
> designed for automated tests within an automake framework, but not
> much else.

I have not really looked at csunit... But if it is really very similar
to JUnit, maybe someone can make some simple mods to the following
document: a for-dummies' like howto on JUnit I wrote a little while
back.  I did that because I wanted something smaller / simpler than
what was available on

Date: March 2, 2002

JUnit For Dummies


This document is a brief introduction to Junit, a “Unit Tester” for Java programs, written in Java.


About JUnit


JUnit is an open source tool that can be used to perform “Unit Testing” of Java programs.  The latest version, as of this writing, is JUnit 3.7.  It can be downloaded from:



What is Unit Testing?


A “Unit Test” is a simple piece of test code that tests one teeny-weeny bit of your program.  A Unit Test does not test application level functionality.  A Unit Testing tool is a framework that makes it Easy™ to write, maintain, execute, and collect & present results from, a number of unit tests.


With JUnit, we can do all of the above.  JUnit comes with a graphical interface as well as a command line interface.  It also interacts with sophisticated development environments like IBMÂ’s VisualAge for Java


Using JUnit


Using the JUnit testing framework will involve the following steps:


  • Writing tests
  • Executing the tests and collecting/viewing results.


Writing tests


You should first write a class that extends junit.framework.TestCase like this:


import junit.framework.*;

public class MyTest extends TestCase



Each unit test you write will be a method of this class.  It is a popular convention to give the tests a name that starts with `testÂ’.


The code below shows a class with two tests:


public class MyArithTests extends TestCase


     public MyArithTests (String name)





     public void test_one()


              int a = 1, b = 2, c;

              c = a + b;

              assert( 3 == c);



     public void test_two()


              int a = 1, b = 2, c;

              c = a * b;

              assert( 2 == c);




assert() is a function that is available via the TestCase class.  The assert succeeds if the condition passed to it is true, and it fails otherwise. test_one wants to check if JavaÂ’s implementation of the “+” operator is right or wrong!!  When an assert fails, the JUnit makes a note that the test has failed, and if a test routine returns without any error/failure, JUnit makes a note that the test has succeeded.


Add as many unit tests as you like, and compile the java file(s).


Executing the Unit Tests


The JUnit framework can present the test results in three different interfaces – a command-line interface, and two graphical interfaces, one each based on java.awt and java.swing APIs.  The invocation of the test execution command depends on which interface you want the results in.


If you want a vanilla awt-based output, issue the following command:


java junit.awtui.TestRunner MyArithTests


If you are in the mood for a swing-enhanced user experience, fire the following command:


java junit.swingui.TestRunner MyArithTests


If you are in a graphics-impaired state, the following might be the recipe for you:


java junit.textui.TestRunner MyArithTests



What happens, really, is quite simple.  The main function in TestRunner extracts all the methods from the MyArithTests class that start with “test” and runs them, keeping track of any errors that occur while that happens.  Errors include failed `assert()Â’s, exceptions and all that stuff.  Screenshots and the like are beyond the scope of this document writerÂ’s abilities.  Readers are encouraged to experience the feeling themselves.



Expert JUnit!!


What we have seen is the simplest way to invoke and use JUnit.  It is more than likely that testing non-trivial code will need non-trivial testing.  There are some additional features in JUnit that we will touch upon here. 


setUp() and tearDown()


In the example above, both test_one() and test_two() declared and used the same variables a, b, c, and even assigned the same values to a, b.  It would be great if we can simply set them up once and reuse them.  This will be a recurring pattern.  We will want to setup a set of objects and use them in different tests.  In a normal class, we could have made a, b, c as private members and written a constructor to initialize the variables of our choice.  But overloading constructors like this will not work with the JUnit framework, and so there is a method called setUp() which can be overridden to initialize our variables.  The following code snippet shows how we could use the setUp method:


public class MyArithTests extends TestCase


            private int a, b, c;

            void setUp()


                        a = 1; b = 2;


            // Â… Snipped



As you would have guessed, tearDown() is run at windup time.  You can use it, perhaps, to do some reporting of your own or whatever!




JUnit is a very simple tool that can be used to organize and easily execute a number of test cases, which can be built incrementally.  This document did not cover all features of JUnit but is only meant to be an introduction with which you can get right into using JUnit beneficially.

"Have you ever fought an IDEA, Picard?"
      -- Gowron, Star Trek, TNG

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