From: Mike C. <cla...@us...> - 2004-10-28 15:39:36
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Update of /cvsroot/junit/junit/doc/faq In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv7259 Modified Files: faq.htm Log Message: Index: faq.htm =================================================================== RCS file: /cvsroot/junit/junit/doc/faq/faq.htm,v retrieving revision 1.27 retrieving revision 1.28 diff -u -d -r1.27 -r1.28 --- faq.htm 23 Sep 2004 21:19:56 -0000 1.27 +++ faq.htm 28 Oct 2004 15:39:10 -0000 1.28 @@ -1,4 +1,5 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <html> <head> <title>JUnit FAQ</title> <meta http-equiv=Content-Type content="text/html; charset=iso-8859-1"> </head> <body> <h1><font color=#33ff33>J</font><font color=#cc0000>U</font>nit FAQ</h1> </p> <p></p> <hr size="1"> <!-- Summary --> <i> <p> JUnit is an open source Java testing framework used to write and run repeatable tests. <p> It is an instance of the xUnit architecture for unit testing frameworks. </i> <hr size="1"> <p> Maintained by:<br/> <a href="mailto:mi...@cl...">Mike Clark</a><br/> <a href="http://www.clarkware.com">Clarkware Consulting, Inc.</a> </p> <p> Last modified on September 23, 2004 </p> <hr> <br> <!-- Table Of Contents --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td> <b><font color="#000000" size="+1"> <a name="toc">Table of Contents:</a> </font></b> </td> </tr> </table> <ol> <li><b><a href="#faqinfo">FAQ Info:</a></b> <ol> <li><a href="#faqinfo_1">Who is responsible for this FAQ?</a></li> <li><a href="#faqinfo_2">How can I contribute to this FAQ?</a></li> <li><a href="#faqinfo_3">Where do I get the latest version of this FAQ?</a></li> </ol> </li> <p> <li><b><a href="#overview">Overview:</a></b> <ol> <li><a href="#overview_1">What is JUnit?</a></li> <li><a href="#overview_2">Where is the JUnit home page?</a></li> <li><a href="#overview_3">Where are the JUnit mailing lists and forums?</a></li> <li><a href="#overview_4">Where is the JUnit documentation?</a></li> <li><a href="#overview_5">Where can I find articles on JUnit?</a></li> <li><a href="#overview_6">What's the latest news on JUnit?</a></li> <li><a href="#overview_7">How is JUnit licensed?</a></li> <li><a href="#overview_8">What awards has JUnit won?</a></li> </ol> </li> <p> <li><b><a href="#started">Getting Started:</a></b> <ol> <li><a href="#started_1">Where do I download JUnit?</a></li> <li><a href="#started_2">How do I install JUnit?</a></li> <li><a href="#started_3">How do I uninstall JUnit?</a></li> <li><a href="#started_4">How do I ask questions?</a></li> <li><a href="#started_5">How do I submit bugs, patches, or feature requests?</a></li> </ol> </li> <p> <li><b><a href="#tests">Writing Tests:</a></b> <ol> <li><a href="#tests_1">How do I write and run a simple test?</a></li> <li><a href="#tests_2">How do I use a test fixture?</a></li> <li><a href="#tests_3">Why isn't my test fixture being run?</a></li> <li><a href="#tests_4">How do I test a method that doesn't return anything?</a></li> <li><a href="#tests_5">Under what conditions should I test get() and set() methods?</a></li> <li><a href="#tests_6">Under what conditions should I not test get() and set() methods?</a></li> <li><a href="#tests_7">How do I write a test that passes when an expected exception is thrown?</a></li> <li><a href="#tests_8">How do I write a test that fails when an unexpected exception is thrown?</a></li> <li><a href="#tests_9">What's the difference between a failure and an error?</a></li> <li><a href="#tests_10">How do I test protected methods?</a></li> <li><a href="#tests_11">How do I test private methods?</a></li> <li><a href="#tests_12">Why does JUnit only report the first failure in a single test?</a></li> <li><a href="#tests_13">In Java 1.4, 'assert' is a keyword. Won't this conflict with JUnit's assert() method?</a></li> <li><a href="#tests_14">How do I test things that must be run in a J2EE container (e.g. servlets, EJBs)?</a></li> <li><a href="#tests_15">Do I need to write a TestCase class for every class I need to test?</a></li> <li><a href="#tests_16">Is there a basic template I can use to create a test?</a></li> <li><a href="#tests_17">How do I write a test for an abstract class?</a></li> </ol> </li> <p> <li><b><a href="#organize">Organizing Tests:</a></b> <ol> <li><a href="#organize_1">Where should I put my test files?</a></li> <li><a href="#organize_2">How do I write a test suite for all of my tests?</a></li> <li><a href="#organize_3">How can I run setUp() and tearDown() code once for all of my tests?</a></li> </ol> </li> <p> <li><b><a href="#running">Running Tests:</a></b> <ol> <li><a href="#running_1">What CLASSPATH settings are needed to run JUnit?</a> </li> <li><a href="#running_2">Why do I get a NoClassDefFoundError when trying to test JUnit or run the samples?</a> </li> <li><a href="#running_3">How do I run the JUnit GUI test runner?</a> </li> <li><a href="#running_4">How do I run JUnit from my command window?</a> </li> <li><a href="#running_5">How do I run JUnit using Ant?</a> </li> <li><a href="#running_6">How do I use Ant to create HTML test reports?</a> </li> <li><a href="#running_7">How do I pass command-line arguments to a test execution?</a> </li> <li><a href="#running_8">Why do I get an error (ClassCastException or LinkageError) using the GUI TestRunners?</a> </li> <li><a href="#running_9">Why do I get a LinkageError when using XML interfaces in my TestCase?</a> </li> <li><a href="#running_10">Why do I get a ClassCastException when I use narrow() in an EJB client TestCase?</a> </li> <li><a href="#running_11">Why do I get the warning "AssertionFailedError: No tests found in XXX" when I run my test?</a> </li> <li><a href="#running_12">Why do I see "Unknown Source" in the stack trace of a test failure, rather than the source file's line number?</a> </li> <li><a href="#running_13">Why does the "excluded.properties" trick not work when running JUnit's GUI from inside my favorite IDE?</a> </li> <li><a href="#running_14">How do I get one test suite to invoke another?</a> </li> <li><a href="#running_15">How do I organize all test classes in a TestSuite automatically and not use or manage a TestSuite explicitly?</a> </li> </ol> </li> <p> <li><b><a href="#best">Best Practices:</a></b> <ol> <li><a href="#best_1">When should tests be written?</a></li> <li><a href="#best_2">Do I have to write a test for everything?</a></li> <li><a href="#best_3">How simple is 'too simple to break'?</a></li> <li><a href="#best_4">How often should I run my tests?</a></li> <li><a href="#best_5">What do I do when a defect is reported?</a></li> <li><a href="#best_6">Why not just use System.out.println()?</a></li> <li><a href="#best_7">Why not just use a debugger?</a></li> </ol> </li> <p> <li><b><a href="#extend">Extending JUnit:</a></b> <ol> <li><a href="#extend_1">How do I extend JUnit?</a></li> <li><a href="#extend_2">What kinds of extensions are available?</a></li> </ol> </li> <p> <li><b><a href="#misc">Miscellaneous:</a></b> <ol> <li><a href="#misc_1">How do I integrate JUnit with my IDE?</a></li> <li><a href="#misc_2">How do I launch a debugger when a test fails?</a></li> <li><a href="#misc_3">Where can I find unit testing frameworks similar to JUnit for other languages?</a></li> </ol> </li> </ol> <!-- FAQ Info --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td align="left" width="90%"> <a name="faqinfo"><b><font size="+1">FAQ Info:</font></b></a> </td> <td align="right"> <a href="#toc">top</a> </td> </tr> </table> <ol> <li><b><a name="faqinfo_1">Who is responsible for this FAQ?</a></b> <p> The current version of this FAQ is maintained by <a href="mailto:mi...@cl...">Mike Clark</a>. <p> Most of the wisdom contained in this FAQ comes from the collective insights and hard-won experiences of the many good folks who participate on the JUnit mailing list and the JUnit community at large. <p> If you see your genius represented anywhere in this FAQ without due credit to you, please send me an email and I'll make things right. <p></p> <hr size="1"> </li> <li><b><a name="faqinfo_2">How can I contribute to this FAQ?</a></b> <p> Your contributions to this FAQ are greatly appreciated! The JUnit community thanks you in advance. <p> To contribute to this FAQ, simply write a JUnit-related quest ion and answer, then send the unformatted text to <a href="mailto:mi...@cl...">Mike Clark</a>. Corrections to this FAQ are always appreciated, as well. <p> No reasonable contribution will be denied. Your name will always appear along with any contribution you make. <p></p> <hr size="1"> </li> <li><b><a name="faqinfo_3">Where do I get the latest version of this FAQ?</a></b> <p> The master copy of this FAQ is available at <a href="http://junit.sourceforge.net/doc/faq/faq.htm">http://junit.sourceforge.net/doc/faq/faq.htm</a>. <p> The entries in this FAQ are also documented in the <a href="http://www.jguru.com/faq/JUnit">jGuru FAQ</a>. <p> The JUnit distribution also includes this FAQ in the <code>doc</code> directory. <p></p> <hr size="1"> </li> </ol> <!-- Overview --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td align="left" width="90%"> <a name="overview"><b><font size="+1">Overview:</font></b></a> </td> <td align="right"> <a href="#toc">top</a> </td> </tr> </table> <ol> <li><b><a name="overview_1">What is JUnit?</a></b> <p> JUnit is an open source Java testing framework used to write and run repeatable tests. It is an instance of the xUnit architecture for unit testing frameworks. <p> JUnit features include: <ul> <li>Assertions for testing expected results</li> <li>Test fixtures for sharing common test data</li> <li>Test suites for easily organizing and running tests</li> <li>Graphical and textual test runners</li> </ul> <p> JUnit was originally written by Erich Gamma and Kent Beck. <p></p> <hr size="1"> </li> <li><b><a name="overview_2">Where is the JUnit home page?</a></b> <p> The official JUnit home page is <a href="http://junit.org">http://junit.org</a>. <p></p> <hr size="1"> </li> <li><b><a name="overview_3">Where are the JUnit mailing lists and forums?</a></b> <p> There are 3 mailing lists dedicated to everything JUnit: <ul> <li><a href="http://lists.sourceforge.net/lists/listinfo/junit-announce">JUnit announcements</a></li> <li><a href="http://groups.yahoo.com/group/junit/">JUnit user list</a></li> <li><a href="http://lists.sourceforge.net/lists/listinfo/junit-devel">JUnit developer list</a></li> </ul> <p> You can <a href="http://groups.yahoo.com/group/junit/">search</a> the JUnit user list archives for answers to frequently asked questions not included here. <p> There is also a <a href="http://www.jguru.com/forums/home.jsp?topic=JUnit">jGuru discussion forum</a> dedicated to everything JUnit. <p></p> <hr size="1"> </li> <li><b><a name="overview_4">Where is the JUnit documentation?</a></b> <p> The following documents are included in the JUnit distribution in the <code>doc</code> directory: <ul> <li><a href="http://junit.sourceforge.net/doc/testinfected/testing.htm">JUnit Test Infected: Programmers Love Writing Tests</a></li> <li><a href="http://junit.sourceforge.net/doc/cookbook/cookbook.htm">JUnit Cookbook</a></li> <li><a href="http://junit.sourceforge.net/doc/cookstour/cookstour.htm">JUnit - A Cook's Tour</a></li> <li><a href="http://junit.sourceforge.net/doc/faq/faq.htm">JUnit FAQ</a></li> </ul> <p></p> <hr size="1"> </li> <li><b><a name="overview_5">Where can I find articles on JUnit?</a></b> <p> The JUnit home page maintains a list of <a href="http://www.junit.org/news/article/index.htm">JUnit articles</a>. <p></p> <hr size="1"> </li> <li><b><a name="overview_6">What's the latest news on JUnit?</a></b> <p> The JUnit home page publishes the <a href="http://www.junit.org/news/index.htm">latest JUnit news</a>. <p></p> <hr size="1"> </li> <li><b><a name="overview_7">How is JUnit licensed?</a></b> <p> JUnit is <a href="http://www.opensource.org/">Open Source Software</a>, released under <a href="http://oss.software.ibm.com/developerworks/oss/license-cpl.html">IBM's Common Public License Version 0.5</a> and hosted on <a href="http://sourceforge.net/projects/junit/">SourceForge</a>. <p></p> <hr size="1"> </li> <li><b><a name="overview_8">What awards has JUnit won?</a></b> <p> <ul> <li> <a href="http://www.javaworld.com/javaworld/jw-03-2002/jw-0326-awards.html">2002 JavaWorld Editors' Choice Awards (ECA)</a> <p> Best Java Performance Monitoring/Testing Tool </li> <li> <a href="http://www.javaworld.com/javaworld/jw-06-2001/j1-01-awards.html">2001 JavaWorld Editors' Choice Awards (ECA)</a> <p> Best Java Performance Monitoring/Testing Tool </li> </ul> <p></p> <hr size="1"> </li> </ol> <!-- Getting Started --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td align="left" width="90%"> <a name="started"><b><font size="+1">Getting Started:</font></b></a> </td> <td align="right"> <a href="#toc">top</a> </td> </tr> </table> <ol> <li><b><a name="started_1">Where do I download JUnit?</a></b> <p> The latest version of JUnit is available on <a href="http://sourceforge.net/project/showfiles.php?group_id=15278">SourceForge</a>. <p></p> <hr size="1"> </li> <li><b><a name="started_2">How do I install JUnit?</a></b> <p> <ol> <li> First, <a href="http://sourceforge.net/project/showfiles.php?group_id=15278">download</a> the latest version of JUnit, referred to below as <code>junit.zip</code>. </li> <br><br> <li> Then install JUnit on your platform of choice: <p> <u>Windows</u> <p> To install JUnit on Windows, follow these steps: <p> <ol> <li>Unzip the <code>junit.zip</code> distribution file to a directory referred to as <code>%JUNIT_HOME%</code>. </li> <p> <li>Add JUnit to the classpath: <p> <code>set CLASSPATH=%CLASSPATH%;%JUNIT_HOME%\junit.jar</code> </li> </ol> <p> <u>Unix (bash)</u> <p> To install JUnit on Unix, follow these steps: <p> <ol> <li>Unzip the <code>junit.zip</code> distribution file to a directory referred to as <code>$JUNIT_HOME</code>. </li> <p> <li>Add JUnit to the classpath: <p> <code>export CLASSPATH=$CLASSPATH:$JUNIT_HOME/junit.jar</code> </li> </ol> </li> <br> <li> <i>(Optional)</i> Unzip the <code>$JUNIT_HOME/src.jar</code> file. </li> <br><br> <li> Test the installation by using either the textual or graphical test runner to run the sample tests distributed with JUnit. <p> <i>Note: The sample tests are not contained in the <code>junit.jar</code>, but in the installation directory directly. Therefore, make sure that the JUnit installation directory is in the CLASSPATH.</i> <p> For the textual TestRunner, type: <p> <blockquote><pre> java junit.textui.TestRunner junit.samples.AllTests </pre></blockquote> <p> For the graphical TestRunner, type: <p> <blockquote><pre> java junit.swingui.TestRunner junit.samples.AllTests </pre></blockquote> <p> All the tests should pass with an "OK" (textual) or a green bar (graphical). <p> If the tests don't pass, verify that <code>junit.jar</code> is in the CLASSPATH. </li> <br><br> <li> Finally, <a href="#overview_4">read</a> the documentation. </li> </ol> <p></p> <hr size="1"> </li> <li><b><a name="started_3">How do I uninstall JUnit?</a></b> <p> <ol> <li>Delete the directory structure where you unzipped the JUnit distribution </li> <br> <li>Remove <code>junit.jar</code> from the classpath </li> </ol> <p> JUnit does not modify the registry so simply removing all the files will fully uninstall it. <p></p> <hr size="1"> </li> <li><b><a name="started_4">How do I ask questions?</a></b> <p> Questions that are not answered in the <a href="http://junit.sourceforge.net/doc/faq/faq.htm">FAQ</a> or in the <a href="#overview_4">documentation</a> should be posted to the <a href="http://www.jguru.com/forums/home.jsp?topic=JUnit">jGuru discussion forum</a> or the <a href="http://groups.yahoo.com/group/junit/">JUnit user mailing list</a>. </p> <p> Please stick to technical issues on the discussion forum and mailing lists. Keep in mind that these are public, so do <b>not</b> include any confidental information in your questions! <p> You should also read <a href="http://www.catb.org/~esr/faqs/smart-questions.html">"How to ask questions the smart way"</a> by Eric Raymond before participating in the discussion forum and mailing lists. <p> <i> NOTE: <br> Please do NOT submit bugs, patches, or feature requests to the discussion forum or mailing lists. <br> Refer instead to <a href="#started_5">"How do I submit bugs, patches, or feature requests?"</a>. </i> <p></p> <hr size="1"> </li> <li><b><a name="started_5">How do I submit bugs, patches, or feature requests?</a></b> <p> JUnit celebrates programmers testing their own software. In this spirit, bugs, patches, and feature requests that include JUnit tests have a better chance of being addressed than those without. <p> JUnit is forged on <a href="http://sourceforge.net/projects/junit">SourceForge</a>. Please use the tools provided by SourceForge for your submissions. <p></p> <hr size="1"> </li> </ol> <!-- Writing Tests --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td align="left" width="90%"> <a name="tests"><b><font size="+1">Writing Tests:</font></b></a> </td> <td align="right"> <a href="#toc">top</a> </td> </tr> </table> <ol> <li><b><a name="tests_1"></a>How do I write and run a simple test?</b> <p> <ol> <li>Create a subclass of <code>TestCase</code>: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> package junitfaq; import java.util.*; import junit.framework.*; public class SimpleTest extends TestCase { </pre></table> </li> <br> <li>Write a test method to assert expected results on the object under test: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> public void testEmptyCollection() { Collection collection = new ArrayList(); assertTrue(collection.isEmpty()); } </pre></table> </li> <br> <li>Write a <code>suite()</code> method that uses reflection to dynamically create a test suite containing all the <code>testXXX()</code> methods: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> public static Test suite() { return new TestSuite(SimpleTest.class); } </pre></table> </li> <br> <li>Write a <code>main()</code> method to conveniently run the test with the textual test runner: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> public static void main(String args[]) { junit.textui.TestRunner.run(suite()); } } </pre></table> </li> <br> <li>Run the test: <p> <ul> <li> To run the test with the textual test runner used in <code>main()</code>, type: <p> <blockquote><pre> java junitfaq.SimpleTest </pre></blockquote> <p> The passing test results in the following textual output: <p> <blockquote><pre> . Time: 0 OK (1 tests) </pre></blockquote> <br> <li> To run the test with the graphical test runner, type: <p> <blockquote><pre> java junit.swingui.TestRunner junitfaq.SimpleTest </pre></blockquote> <p> The passing test results in a green bar displayed in the graphical UI. </ul> </li> </ol> <p></p> <hr size="1"> </li> <li><b><a name="tests_2"></a>How do I use a test fixture?</b> <p> A test fixture is useful if you have two or more tests for a common set of objects. Using a test fixture avoids duplicating the test code necessary to initialize and cleanup those common objects for each test. <p> +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <html> <head> <title>JUnit FAQ</title> <meta http-equiv=Content-Type content="text/html; charset=iso-8859-1"> </head> <body> <h1><font color=#33ff33>J</font><font color=#cc0000>U</font>nit FAQ</h1> </p> <p></p> <hr size="1"> <!-- Summary --> <i> <p> JUnit is an open source Java testing framework used to write and run repeatable tests. <p> It is an instance of the xUnit architecture for unit testing frameworks. </i> <hr size="1"> <p> Maintained by:<br/> <a href="mailto:mi...@cl...">Mike Clark</a><br/> <a href="http://www.clarkware.com">Clarkware Consulting, Inc.</a> </p> <p> Last modified on October 28, 2004 </p> <hr> <br> <!-- Table Of Contents --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td> <b><font color="#000000" size="+1"> <a name="toc">Table of Contents:</a> </font></b> </td> </tr> </table> <ol> <li><b><a href="#faqinfo">FAQ Info:</a></b> <ol> <li><a href="#faqinfo_1">Who is responsible for this FAQ?</a></li> <li><a href="#faqinfo_2">How can I contribute to this FAQ?</a></li> <li><a href="#faqinfo_3">Where do I get the latest version of this FAQ?</a></li> </ol> </li> <p> <li><b><a href="#overview">Overview:</a></b> <ol> <li><a href="#overview_1">What is JUnit?</a></li> <li><a href="#overview_2">Where is the JUnit home page?</a></li> <li><a href="#overview_3">Where are the JUnit mailing lists and forums?</a></li> <li><a href="#overview_4">Where is the JUnit documentation?</a></li> <li><a href="#overview_5">Where can I find articles on JUnit?</a></li> <li><a href="#overview_6">What's the latest news on JUnit?</a></li> <li><a href="#overview_7">How is JUnit licensed?</a></li> <li><a href="#overview_8">What awards has JUnit won?</a></li> </ol> </li> <p> <li><b><a href="#started">Getting Started:</a></b> <ol> <li><a href="#started_1">Where do I download JUnit?</a></li> <li><a href="#started_2">How do I install JUnit?</a></li> <li><a href="#started_3">How do I uninstall JUnit?</a></li> <li><a href="#started_4">How do I ask questions?</a></li> <li><a href="#started_5">How do I submit bugs, patches, or feature requests?</a></li> </ol> </li> <p> <li><b><a href="#tests">Writing Tests:</a></b> <ol> <li><a href="#tests_1">How do I write and run a simple test?</a></li> <li><a href="#tests_2">How do I use a test fixture?</a></li> <li><a href="#tests_3">Why isn't my test fixture being run?</a></li> <li><a href="#tests_4">How do I test a method that doesn't return anything?</a></li> <li><a href="#tests_5">Under what conditions should I test get() and set() methods?</a></li> <li><a href="#tests_6">Under what conditions should I not test get() and set() methods?</a></li> <li><a href="#tests_7">How do I write a test that passes when an expected exception is thrown?</a></li> <li><a href="#tests_8">How do I write a test that fails when an unexpected exception is thrown?</a></li> <li><a href="#tests_9">What's the difference between a failure and an error?</a></li> <li><a href="#tests_10">How do I test protected methods?</a></li> <li><a href="#tests_11">How do I test private methods?</a></li> <li><a href="#tests_12">Why does JUnit only report the first failure in a single test?</a></li> <li><a href="#tests_13">In Java 1.4, 'assert' is a keyword. Won't this conflict with JUnit's assert() method?</a></li> <li><a href="#tests_14">How do I test things that must be run in a J2EE container (e.g. servlets, EJBs)?</a></li> <li><a href="#tests_15">Do I need to write a TestCase class for every class I need to test?</a></li> <li><a href="#tests_16">Is there a basic template I can use to create a test?</a></li> <li><a href="#tests_17">How do I write a test for an abstract class?</a></li> +<li><a href="#tests_18">When are tests garbage collected?</a></li> </ol> </li> <p> <li><b><a href="#organize">Organizing Tests:</a></b> <ol> <li><a href="#organize_1">Where should I put my test files?</a></li> <li><a href="#organize_2">How do I write a test suite for all of my tests?</a></li> <li><a href="#organize_3">How can I run setUp() and tearDown() code once for all of my tests?</a></li> </ol> </li> <p> <li><b><a href="#running">Running Tests:</a></b> <ol> <li><a href="#running_1">What CLASSPATH settings are needed to run JUnit?</a> </li> <li><a href="#running_2">Why do I get a NoClassDefFoundError when trying to test JUnit or run the samples?</a> </li> <li><a href="#running_3">How do I run the JUnit GUI test runner?</a> </li> <li><a href="#running_4">How do I run JUnit from my command window?</a> </li> <li><a href="#running_5">How do I run JUnit using Ant?</a> </li> <li><a href="#running_6">How do I use Ant to create HTML test reports?</a> </li> <li><a href="#running_7">How do I pass command-line arguments to a test execution?</a> </li> <li><a href="#running_8">Why do I get an error (ClassCastException or LinkageError) using the GUI TestRunners?</a> </li> <li><a href="#running_9">Why do I get a LinkageError when using XML interfaces in my TestCase?</a> </li> <li><a href="#running_10">Why do I get a ClassCastException when I use narrow() in an EJB client TestCase?</a> </li> <li><a href="#running_11">Why do I get the warning "AssertionFailedError: No tests found in XXX" when I run my test?</a> </li> <li><a href="#running_12">Why do I see "Unknown Source" in the stack trace of a test failure, rather than the source file's line number?</a> </li> <li><a href="#running_13">Why does the "excluded.properties" trick not work when running JUnit's GUI from inside my favorite IDE?</a> </li> <li><a href="#running_14">How do I get one test suite to invoke another?</a> </li> <li><a href="#running_15">How do I organize all test classes in a TestSuite automatically and not use or manage a TestSuite explicitly?</a> </li> </ol> </li> <p> <li><b><a href="#best">Best Practices:</a></b> <ol> <li><a href="#best_1">When should tests be written?</a></li> <li><a href="#best_2">Do I have to write a test for everything?</a></li> <li><a href="#best_3">How simple is 'too simple to break'?</a></li> <li><a href="#best_4">How often should I run my tests?</a></li> <li><a href="#best_5">What do I do when a defect is reported?</a></li> <li><a href="#best_6">Why not just use System.out.println()?</a></li> <li><a href="#best_7">Why not just use a debugger?</a></li> </ol> </li> <p> <li><b><a href="#extend">Extending JUnit:</a></b> <ol> <li><a href="#extend_1">How do I extend JUnit?</a></li> <li><a href="#extend_2">What kinds of extensions are available?</a></li> </ol> </li> <p> <li><b><a href="#misc">Miscellaneous:</a></b> <ol> <li><a href="#misc_1">How do I integrate JUnit with my IDE?</a></li> <li><a href="#misc_2">How do I launch a debugger when a test fails?</a></li> <li><a href="#misc_3">Where can I find unit testing frameworks similar to JUnit for other languages?</a></li> </ol> </li> </ol> <!-- FAQ Info --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td align="left" width="90%"> <a name="faqinfo"><b><font size="+1">FAQ Info:</font></b></a> </td> <td align="right"> <a href="#toc">top</a> </td> </tr> </table> <ol> <li><b><a name="faqinfo_1">Who is responsible for this FAQ?</a></b> <p> The current version of this FAQ is maintained by <a href="mailto:mi...@cl...">Mike Clark</a>. <p> Most of the wisdom contained in this FAQ comes from the collective insights and hard-won experiences of the many good folks who participate on the JUnit mailing list and the JUnit community at large. <p> If you see your genius represented anywhere in this FAQ without due credit to you, please send me an email and I'll make things right. <p></p> <hr size="1"> </li> <li><b><a name="faqinfo_2">How can I contribute to this FAQ?</a></b> <p> Your contributions to this FAQ are greatly appreciated! The JUnit community thanks you in advance. <p> To contribute to this FAQ, simply write a JUnit-related question and answer, then send the unformatted text to <a href="mailto:mi...@cl...">Mike Clark</a>. Corrections to this FAQ are always appreciated, as well. <p> No reasonable contribution will be denied. Your name will always appear along with any contribution you make. <p></p> <hr size="1"> </li> <li><b><a name="faqinfo_3">Where do I get the latest version of this FAQ?</a></b> <p> The master copy of this FAQ is available at <a href="http://junit.sourceforge.net/doc/faq/faq.htm">http://junit.sourceforge.net/doc/faq/faq.htm</a>. <p> The entries in this FAQ are also documented in the <a href="http://www.jguru.com/faq/JUnit">jGuru FAQ</a>. <p> The JUnit distribution also includes this FAQ in the <code>doc</code> directory. <p></p> <hr size="1"> </li> </ol> <!-- Overview --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td align="left" width="90%"> <a name="overview"><b><font size="+1">Overview:</font></b></a> </td> <td align="right"> <a href="#toc">top</a> </td> </tr> </table> <ol> <li><b><a name="overview_1">What is JUnit?</a></b> <p> JUnit is an open source Java testing framework used to write and run repeatable tests. It is an instance of the xUnit architecture for unit testing frameworks. <p> JUnit features include: <ul> <li>Assertions for testing expected results</li> <li>Test fixtures for sharing common test data</li> <li>Test suites for easily organizing and running tests</li> <li>Graphical and textual test runners</li> </ul> <p> JUnit was originally written by Erich Gamma and Kent Beck. <p></p> <hr size="1"> </li> <li><b><a name="overview_2">Where is the JUnit home page?</a></b> <p> The official JUnit home page is <a href="http://junit.org">http://junit.org</a>. <p></p> <hr size="1"> </li> <li><b><a name="overview_3">Where are the JUnit mailing lists and forums?</a></b> <p> There are 3 mailing lists dedicated to everything JUnit: <ul> <li><a href="http://lists.sourceforge.net/lists/listinfo/junit-announce">JUnit announcements</a></li> <li><a href="http://groups.yahoo.com/group/junit/">JUnit user list</a></li> <li><a href="http://lists.sourceforge.net/lists/listinfo/junit-devel">JUnit developer list</a></li> </ul> <p> You can <a href="http://groups.yahoo.com/group/junit/">search</a> the JUnit user list archives for answers to frequently asked questions not included here. <p> There is also a <a href="http://www.jguru.com/forums/home.jsp?topic=JUnit">jGuru discussion forum</a> dedicated to everything JUnit. <p></p> <hr size="1"> </li> <li><b><a name="overview_4">Where is the JUnit documentation?</a></b> <p> The following documents are included in the JUnit distribution in the <code>doc</code> directory: <ul> <li><a href="http://junit.sourceforge.net/doc/testinfected/testing.htm">JUnit Test Infected: Programmers Love Writing Tests</a></li> <li><a href="http://junit.sourceforge.net/doc/cookbook/cookbook.htm">JUnit Cookbook</a></li> <li><a href="http://junit.sourceforge.net/doc/cookstour/cookstour.htm">JUnit - A Cook's Tour</a></li> <li><a href="http://junit.sourceforge.net/doc/faq/faq.htm">JUnit FAQ</a></li> </ul> <p></p> <hr size="1"> </li> <li><b><a name="overview_5">Where can I find articles on JUnit?</a></b> <p> The JUnit home page maintains a list of <a href="http://www.junit.org/news/article/index.htm">JUnit articles</a>. <p></p> <hr size="1"> </li> <li><b><a name="overview_6">What's the latest news on JUnit?</a></b> <p> The JUnit home page publishes the <a href="http://www.junit.org/news/index.htm">latest JUnit news</a>. <p></p> <hr size="1"> </li> <li><b><a name="overview_7">How is JUnit licensed?</a></b> <p> JUnit is <a href="http://www.opensource.org/">Open Source Software</a>, released under <a href="http://oss.soft ware.ibm.com/developerworks/oss/license-cpl.html">IBM's Common Public License Version 0.5</a> and hosted on <a href="http://sourceforge.net/projects/junit/">SourceForge</a>. <p></p> <hr size="1"> </li> <li><b><a name="overview_8">What awards has JUnit won?</a></b> <p> <ul> <li> <a href="http://www.javaworld.com/javaworld/jw-03-2002/jw-0326-awards.html">2002 JavaWorld Editors' Choice Awards (ECA)</a> <p> Best Java Performance Monitoring/Testing Tool </li> <li> <a href="http://www.javaworld.com/javaworld/jw-06-2001/j1-01-awards.html">2001 JavaWorld Editors' Choice Awards (ECA)</a> <p> Best Java Performance Monitoring/Testing Tool </li> </ul> <p></p> <hr size="1"> </li> </ol> <!-- Getting Started --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td align="left" width="90%"> <a name="started"><b><font size="+1">Getting Started:</font></b></a> </td> <td align="right"> <a href="#toc">top</a> </td> </tr> </table> <ol> <li><b><a name="started_1">Where do I download JUnit?</a></b> <p> The latest version of JUnit is available on <a href="http://sourceforge.net/project/showfiles.php?group_id=15278">SourceForge</a>. <p></p> <hr size="1"> </li> <li><b><a name="started_2">How do I install JUnit?</a></b> <p> <ol> <li> First, <a href="http://sourceforge.net/project/showfiles.php?group_id=15278">download</a> the latest version of JUnit, referred to below as <code>junit.zip</code>. </li> <br><br> <li> Then install JUnit on your platform of choice: <p> <u>Windows</u> <p> To install JUnit on Windows, follow these steps: <p> <ol> <li>Unzip the <code>junit.zip</code> distribution file to a directory referred to as <code>%JUNIT_HOME%</code>. </li> <p> <li>Add JUnit to the classpath: <p> <code>set CLASSPATH=%CLASSPATH%;%JUNIT_HOME%\junit.jar</code> </li> </ol> <p> <u>Unix (bash)</u> <p> To install JUnit on Unix, follow these steps: <p> <ol> <li>Unzip the <code>junit.zip</code> distribution file to a directory referred to as <code>$JUNIT_HOME</code>. </li> <p> <li>Add JUnit to the classpath: <p> <code>export CLASSPATH=$CLASSPATH:$JUNIT_HOME/junit.jar</code> </li> </ol> </li> <br> <li> <i>(Optional)</i> Unzip the <code>$JUNIT_HOME/src.jar</code> file. </li> <br><br> <li> Test the installation by using either the textual or graphical test runner to run the sample tests distributed with JUnit. <p> <i>Note: The sample tests are not contained in the <code>junit.jar</code>, but in the installation directory directly. Therefore, make sure that the JUnit installation directory is in the CLASSPATH.</i> <p> For the textual TestRunner, type: <p> <blockquote><pre> java junit.textui.TestRunner junit.samples.AllTests </pre></blockquote> <p> For the graphical TestRunner, type: <p> <blockquote><pre> java junit.swingui.TestRunner junit.samples.AllTests </pre></blockquote> <p> All the tests should pass with an "OK" (textual) or a green bar (graphical). <p> If the tests don't pass, verify that <code>junit.jar</code> is in the CLASSPATH. </li> <br><br> <li> Finally, <a href="#overview_4">read</a> the documentation. </li> </ol> <p></p> <hr size="1"> </li> <li><b><a name="started_3">How do I uninstall JUnit?</a></b> <p> <ol> <li>Delete the directory structure where you unzipped the JUnit distribution </li> <br> <li>Remove <code>junit.jar</code> from the classpath </li> </ol> <p> JUnit does not modify the registry so simply removing all the files will fully uninstall it. <p></p> <hr size="1"> </li> <li><b><a name="started_4">How do I ask questions?</a></b> <p> Questions that are not answered in the <a href="http://junit.sourceforge.net/doc/faq/faq.htm">FAQ</a> or in the <a href="#overview_4">documentation</a> should be posted to the <a href="http://www.jguru.com/forums/home.jsp?topic=JUnit">jGuru discussion forum</a> or the <a href="http://groups.yahoo.com/group/junit/">JUnit user mailing list</a>. </p> <p> Please stick to technical issues on the discussion forum and mailing lists. Keep in mind that these are public, so do <b>not</b> include any confidental information in your questions! <p> You should also read <a href="http://www.catb.org/~esr/faqs/smart-questions.html">"How to ask questions the smart way"</a> by Eric Raymond before participating in the discussion forum and mailing lists. <p> <i> NOTE: <br> Please do NOT submit bugs, patches, or feature requests to the discussion forum or mailing lists. <br> Refer instead to <a href="#started_5">"How do I submit bugs, patches, or feature requests?"</a>. </i> <p></p> <hr size="1"> </li> <li><b><a name="started_5">How do I submit bugs, patches, or feature requests?</a></b> <p> JUnit celebrates programmers testing their own software. In this spirit, bugs, patches, and feature requests that include JUnit tests have a better chance of being addressed than those without. <p> JUnit is forged on <a href="http://sourceforge.net/projects/junit">SourceForge</a>. Please use the tools provided by SourceForge for your submissions. <p></p> <hr size="1"> </li> </ol> <!-- Writing Tests --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td align="left" width="90%"> <a name="tests"><b><font size="+1">Writing Tests:</font></b></a> </td> <td align="right"> <a href="#toc">top</a> </td> </tr> </table> <ol> <li><b><a name="tests_1"></a>How do I write and run a simple test?</b> <p> <ol> <li>Create a subclass of <code>TestCase</code>: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> package junitfaq; import java.util.*; import junit.framework.*; public class SimpleTest extends TestCase { </pre></table> </li> <br> <li>Write a test method to assert expected results on the object under test: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> public void testEmptyCollection() { Collection collection = new ArrayList(); assertTrue(collection.isEmpty()); } </pre></table> </li> <br> <li>Write a <code>suite()</code> method that uses reflection to dynamically create a test suite containing all the <code>testXXX()</code> methods: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> public static Test suite() { return new TestSuite(SimpleTest.class); } </pre></table> </li> <br> <li>Write a <code>main()</code> method to conveniently run the test with the textual test runner: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> public static void main(String args[]) { junit.textui.TestRunner.run(suite()); } } </pre></table> </li> <br> <li>Run the test: <p> <ul> <li> To run the test with the textual test runner used in <code>main()</code>, type: <p> <blockquote><pre> java junitfaq.SimpleTest </pre></blockquote> <p> The passing test results in the following textual output: <p> <blockquote><pre> . Time: 0 OK (1 tests) </pre></blockquote> <br> <li> To run the test with the graphical test runner, type: <p> <blockquote><pre> java junit.swingui.TestRunner junitfaq.SimpleTest </pre></blockquote> <p> The passing test results in a green bar displayed in the graphical UI. </ul> </li> </ol> <p></p> <hr size="1"> </li> <li><b><a name="tests_2"></a>How do I use a test fixture?</b> <p> A test fixture is useful if you have two or more tests for a common set of objects. Using a test fixture avoids duplicating the test code necessary to initialize and cleanup those common objects for each test. <p> Tests can use the objects (variables) in a test fixture, with each test invoking different methods on objects in the fixture and asserting different expected results. Each test runs in its own test fixture to isolate tests from the changes made by other tests. That is, tests don't share the state of objects in the test fixture. Because the tests are isolated, they can be run in any order. <p> To create a test fixture, define a <code>setUp()</code> method that initializes common objects and a <code>tearDown()</code> method to cleanup those objects. The JUnit framework automatically invokes the <code>setUp()</code> method before each test is run and the <code>tearDown()</code> method after each test is run. <p> The following test uses a test fixture to initialize and cleanup a common <code>Collection</code> object such that both tests are isolated from changes made by the other: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> package junitfaq; import junit.framework.*; import java.util.*; public class SimpleTest extends TestCase { private Collection collection; protected void setUp() { collection = new ArrayList(); } protected void tearDown() { collection.clear(); } public void testEmptyCollection() { assertTrue(collection.isEmpty()); } public void testOneItemCollection() { collection.add("itemA"); assertEquals(1, collection.size()); } } </pre></table> <p> Given this test, the methods might execute in the following order: @@ -15,4 +16,14 @@ The ordering of test-method invocations is not guaranteed, so <code>testEmptyCollection()</code> might be executed before <code>testOneItemCollection()</code>. This is why the test methods themselves must be written to be independent of one another. What is guaranteed is that <code>setUp()</code> will execute before each test method and <code>tearDown()</code> will execute after each test method. -</p> <p></p> <hr size="1"> </li> <li><b><a name="tests_3"></a>Why isn't my test fixture being run?</b> <p> Make sure the test fixture methods are defined as follows, noting that both method names are case sensitive: <p> <blockquote><pre> protected void setUp() { // initialization code } protected void tearDown() { // cleanup code } </pre></blockquote> <p></p> <hr size="1"> </li> <li><b><a name="tests_4"></a>How do I test a method that doesn't return anything?</b> <p> <i>(Submitted by: Dave Astels)</i> <p> Often if a method doesn't return a value, it will have some side effect. Actually, if it doesn't return a value AND doesn't have a side effect, it isn't doing anything. <p> There may be a way to verify that the side effect actually occurred as expected. For example, consider the <code>add()</code> method in the Collection classes. There are ways of verifying that the side effect happened (i.e. the object was added). You can check the size and assert that it is what is expected: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> public void testCollectionAdd() { Collection collection = new ArrayList(); assertEquals(0, collection.size()); collection.add("itemA"); assertEquals(1, collection.size()); collection.add("itemB"); assertEquals(2, collection.size()); } </pre></table> <p> Another approach is to make use of <a href="http://www.mockobjects.com">MockObjects</a>. <p> A related issue is to design for testing. For example, if you have a method that is meant to output to a file, don't pass in a filename, or even a <code>FileWriter</code>. Instead, pass in a <code>Writer</code>. That way you can pass in a <code>StringWriter</code> to capture the output for testing purposes. Then you can add a method (e.g. <code>writeToFileNamed(String filename)</code>) to encapsulate the <code>FileWriter</code> creation. <p></p> <hr size="1"> </li> <li><b><a name="tests_5"></a>Under what conditions should I test get() and set() methods?</b> <p> Unit tests are intended to alleviate fear that something might break. If you think a <code>get()</code> or <code>set()</code> method could reasonably break, or has in fact contributed to a defect, then by all means write a test. <p> In short, test until you're confident. What you choose to test is subjective, based on your experiences and confidence level. Remember to be practical and maximize your testing investment. <p> Refer also to <a href="#best_3">"How simple is 'too simple to break'?"</a>. <p></p> <hr size="1"> </li> <li><b><a name="tests_6"></a>Under what conditions should I not test get() and set() methods?</b> <p> <i>(Submitted by: J. B. Rainsberger)</i> <p> Most of the time, get/set methods just can't break, and if they can't break, then why test them? While it is usually better to test more, there is a definite curve of diminishing returns on test effort versus "code coverage". Remember the maxim: "Test until fear turns to boredom." <p> Assume that the <code>getX()</code> method only does "return x;" and that the <code>setX()</code> method only does "this.x = x;". If you write this test: <blockquote><pre> testGetSetX() { setX(23); assertEquals(23, getX()); } </pre></blockquote> then you are testing the equivalent of the following: <blockquote><pre> testGetSetX() { x = 23; assertEquals(23, x); } </pre></blockquote> or, if you prefer, <blockquote><pre> testGetSetX() { assertEquals(23, 23); } </pre></blockquote> At this point, you are testing the Java compiler, or possibly the interpreter, and not your component or application. There is generally no need for you to do Java's testing for them. <p> If you are concerned about whether a property has already been set at the point you wish to call <code>getX()</code>, then you want to test the constructor, and not the <code>getX()</code> method. This kind of test is especially useful if you have multiple constructors: <blockquote><pre> testCreate() { assertEquals(23, new MyClass(23).getX()); } </pre></blockquote> <p></p> <hr size="1"> </li> <li><b><a name="tests_7"></a>How do I write a test that passes when an expected exception is thrown?</b> <p> Catch the exception within the test method. If it isn't thrown, call the <code>fail()</code> method to signal the failure of the test. <p> The following is an example test that passes when the expected <code>IndexOutOfBoundsException</code> is raised: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td> <pre> public void testIndexOutOfBoundsException() { ArrayList emptyList = new ArrayList(); try { Object o = emptyList.get(0); fail("Should raise an IndexOutOfBoundsException"); } catch (IndexOutOfBoundsException success) {} } </pre></table> <p></p> <hr size="1"> </li> <li><b><a name="tests_8"></a>How do I write a test that fails when an unexpected exception is thrown?</b> <p> Declare the exception in the <code>throws</code> clause of the test method and don't catch the exception within the test method. Uncaught exceptions will cause the test to fail with an error. <p> The following is an example test that fails when the <code>IndexOutOfBoundsException</code> is raised: <p> <table><tr><td bgcolor="#cc0000"> </td><td> </td><td> <pre> public void testIndexOutOfBoundsExceptionNotRaised() throws IndexOutOfBoundsException { ArrayList emptyList = new ArrayList(); Object o = emptyList.get(0); } </pre></table> <p></p> <hr size="1"> </li> <li><b><a name="tests_9"></a>What's the difference between a failure and an error?</b> <p> Assertions are used to check for the possibility of failures, therefore failures are anticipated. Errors are unanticipated problems resulting in uncaught exceptions being propagated from a JUnit test method. <p> In the following example, the <code>FileNotFoundException</code> is expected and checked with an assertion. If the expected exception is not raised, then a failure is produced. If any other unexpected <code>IOException</code> or unchecked exception (e.g. <code>NullPointerException</code>) is raised, the JUnit framework catches the exception and signals an error. <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td> <pre> public void testNonexistentFileRead() throws IOException { try { File file = new File("doesNotExist.txt"); FileReader reader = new FileReader(file); assertEquals('a', (char)reader.read()); fail("Read from a nonexistent file?!"); } catch (FileNotFoundException success) {} } </pre></table> <p> In the following example, an <code>IOException</code> is not expected. The JUnit framework will signal an error if an <code>IOException</code> (e.g. <code>FileNotFoundException</code>) or any unchecked exception (e.g. <code>NullPointerException</code>) is raised. <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td> <pre> public void testExistingFileRead() throws IOException { // exists.txt created in setup(), perhaps File file = new File("exists.txt"); FileReader reader = new FileReader(file); assertEquals('a', (char)reader.read()); } </pre></table> <p> Both failures and errors will cause the test to fail. However, it is useful to differentiate between failures and errors because the debugging process is slightly different. <p> In the first example, the use of <code>fail()</code> will not generate a complete stack trace including the method that raised the exception. In this case that's sufficient since we anticipate that the exception will be raised. If it's not raised, then it's a problem with the test itself. <p> In the second example, the JUnit framework catches the exception and generates an error with a complete stack trace for the exception. Since we don't expect this exception to be raised, a complete stack trace is useful in debugging why it was raised. <p></p> <hr size="1"> </li> <li><b><a name="tests_10"></a>How do I test protected methods?</b> <p> Place your tests in the same package as the classes under test. <p> Refer to <a href="#organize_1">"Where should I put my test files?"</a> for examples of how to organize tests for protected method access. <p></p> <hr size="1"> </li> <li><b><a name="tests_11"></a>How do I test private methods?</b> <p> Testing private methods may be an indication that those methods should be moved into another class to promote reusability. <p> But if you must... <p> You can use reflection to subvert the access control mechanism. If you are using JDK 1.3 or higher you can use the <a href="http://groups.yahoo.com/group/junit/files/src/PrivilegedAccessor.java">PrivilegedAccessor</a> class. Examples of how to use this class are available in <a href="http://groups.yahoo.com/group/junit/files/src/PrivilegedAccessorTest.java">PrivilegedAccessorTest</a>. <p></p> <hr size="1"> </li> <li><b><a name="tests_12"></a>Why does JUnit only report the first failure in a single test?</b> <p> <i>(Submitted by: J. B. Rainsberger)</i> <p> Reporting multiple failures in a single test is generally a sign that the test does too much, compared to what a unit test ought to do. Usually this means either that the test is really a functional/acceptance/customer test or, if it is a unit test, then it is too big a unit test. <p> JUnit is designed to work best with a number of small tests. It executes each test within a separate instance of the test class. It reports failure on each test. Shared setup code is most natural when sharing between tests. This is a design decision that permeates JUnit, and when you decide to report multiple failures per test, you begin to fight against JUnit. This is not recommended. <p> Long tests are a design smell and indicate the likelihood of a design problem. Kent Beck is fond of saying in this case that "there is an opportunity to learn something about your design." We would like to see a pattern language develop around these problems, but it has not yet been written down. <p> Finally, note that a single test with multiple assertions is isomorphic to a test case with multiple tests: <p> One test method, three assertions: <p> <blockquote><pre> public class MyTestCase extends TestCase { public void testSomething() { // Set up for the test, manipulating local variables assertTrue(condition1); assertTrue(condition2); assertTrue(condition3); } } </pre></blockquote> <p> Three test methods, one assertion each: <p> <blockquote><pre> public class MyTestCase extends TestCase { // Locale variables become instance variables protected void setUp() { // Set up for the test, manipulating instance variables } public void testCondition1() { assertTrue(condition1); } public void testCondition2() { assertTrue(condition2); } public void testCondition3() { assertTrue(condition3); } } </pre></blockquote> The resulting tests use JUnit's natural execution and reporting mechanism and, failure in one test does not affect the execution of the other tests. You generally want exactly one test to fail for any given bug, if you can manage it. <p></p> <hr size="1"> </li> <li><b><a name="tests_13"></a>In Java 1.4, 'assert' is a keyword. Won't this conflict with JUnit's <code>assert()</code> method?</b> <p> <i>(Submitted by: David Stagner)</i> <p> JUnit 3.7 deprecated <code>assert()</code> and replaced it with <code>assertTrue()</code>, which works exactly the same way. <p> Simply upgrade your JUnit to version 3.7 or higher and change all <code>assert()</code> calls in your existing tests to <code>assertTrue()</code>. <p></p> <hr size="1"> </li> <li><b><a name="tests_14"></a>How do I test things that must be run in a J2EE container (e.g. servlets, EJBs)?</b> <p> Refactoring J2EE components to delegate functionality to other objects that don't have to be run in a J2EE container will improve the design and testability of the software. <p> <a href="http://jakarta.apache.org/cactus/index.html">Cactus</a> is an open source JUnit extension that can be used to test J2EE components in their natural environment. <p></p> <hr size="1"> </li> <li><b><a name="tests_15"></a>Do I need to write a <code>TestCase</code> class for every class I need to test?</b> <p> <i>(Submitted by: J. B. Rainsberger)</i> <p> No. It is a convention to start with one <code>TestCase</code> class per class under test, but it is not necessary. <p> <code>TestCase</code> classes only provide a way to organize tests, nothing more. Generally you will start with one <code>TestCase</code> class per class under test, but then you may find that a small group of tests belong together with their own common test fixture.[1] In this case, you may move those tests to a new <code>TestCase</code> object. This is a simple object-oriented refactoring: separating responsibilities of an object that does too much. <p> Another point to consider is that the <code>TestSuite</code> is the smallest execution unit in JUnit: you cannot execute anything smaller than a TestSuite at one time without changing source code. In this case, you probably do not want to put tests in the same <code>TestCase</code> class unless they somehow "belong together". If you have two groups of tests that you think you'd like to execute separately from one another, it is wise to place them in separate <code>TestCase</code> classes. <p> <i> [1] A test fixture is a common set of test data and collaborating objects shared by many tests. Generally they are implemented as instance variables in the <code>TestCase</code> class. </i> <p></p> <hr size="1"> </li> <li><b><a name="tests_16"></a>Is there a basic template I can use to create a test?</b> <p> <i>(Submitted by: Eric Armstrong)</i> <p> The following templates are a good starting point. Copy/paste and edit these templates to suit your coding style. <p> SampleTest is a basic test template: <p> <blockquote><pre> import junit.framework.TestCase; public class SampleTest extends TestCase { private java.util.List emptyList; /** * Sets up the test fixture. * (Called before every test case method.) */ protected void setUp() { emptyList = new java.util.ArrayList(); } /** * Tears down the test fixture. * (Called after every test case method.) */ protected void tearDown() { emptyList = null; } public void testSomeBehavior() { assertEquals("Empty list should have 0 elements", 0, emptyList.size()); } public void testForException() { try { Object o = emptyList.get(0); fail("Should raise an IndexOutOfBoundsException"); } catch (IndexOutOfBoundsException success) { } } public static void main(String args[]) { junit.textui.TestRunner.run(SampleTest.class); } } </pre></blockquote> SampleTestSuite is a template for a suite of tests: <p> <blockquote><pre> import junit.framework.Test; import junit.framework.TestSuite; public class SampleTestSuite { public static Test suite() { TestSuite suite = new TestSuite("Sample Tests"); // // Add one entry for each test class // or test suite. // suite.addTestSuite(SampleTest.class); // // For a master test suite, use this pattern. // (Note that here, it's recursive!) // suite.addTest(AnotherTestSuite.suite()); return suite; } public static void main(String args[]) { junit.textui.TestRunner.run(suite()); } } </pre></blockquote> <p></p> <hr size="1"> </li> <li><b><a name="tests_17"></a>How do I write a test for an abstract class?</b> <p> Refer to <a href="http://c2.com/cgi/wiki?AbstractTestCases">http://c2.com/cgi/wiki?AbstractTestCases</a>. <p></p> <hr size="1"> </li> </ol> <!-- Organizing Tests --> <table border="0" cellspacing="0" cellpadding="2" width="100%" bgcolor="#33ff33"> <tr> <td align="left" width="90%"> <a name="organize"><b><font size="+1">Organizing Tests:</font></b></a> </td> <td align="right"> <a href="#toc">top</a> </td> </tr> </table> <ol> <li><b><a name="organize_1"></a>Where should I put my test files?</b> <p> You can place your tests in the same package and directory as the classes under test. <p> For example: <blockquote><pre> src com xyz SomeClass.java SomeClassTest.java </pre></blockquote> <p> While adequate for small projects, many developers feel that this approach clutters the source directory, and makes it hard to package up client deliverables without also including unwanted test code, or writing unnecessarily complex packaging tasks. <p> An arguably better way is to place the tests in a separate parallel directory structure with package alignment. <p> For example: <blockquote><pre> src com xyz SomeClass.java test com xyz SomeClassTest.java </pre></blockquote> <p> These approaches allow the tests to access to all the public and package visible methods of the classes under test. <p> Some developers have argued in favor of putting the tests in a sub-package of the classes under test (e.g. com.xyz.test). The author of this FAQ sees no clear advantage to adopting this approach and believes that said developers also put their curly braces on the wrong line. :-) <p></p> <hr size="1"> </li> <li><b><a name="organize_2"></a>How do I write a test suite for all of my tests?</b> <p> Write a <code>suite()</code> method that creates a <code>TestSuite</code> containing all your tests. <p> For example: <p> <table><tr><td bgcolor="#33ff33"> </td><td> </td><td><pre> import junit.framework.*; public class AllTests { public static Test suite() { TestSuite suite = new TestSuite(); suite.addTest(SomeTest.suite()); suite.addTest(AnotherTest.suite()); return suite; } public static void main(String args[]) { junit.textui.TestRunner.run(suite()); } } </pre></table> <p> Running <code>AllTests</code> will automatically run all of its contained tests in one fell swoop. <p> You can arbitrarily group any tests into test suites as appropriate by package, logical layers, test type, etc. <p></p> <hr size="1"> </li> <li><b><a name="organize_3"></a>How can I run setUp() and tearDown() code once for all of my tests?</b> <p> The desire to do this is usually a symptom of excessive coupling in your design. If two or more tests must share the same test fixture state, then the tests may be trying to tell you that the classes under test have some undesirable dependencies. <p> Refactoring the design to further decouple the classes under test and eliminate code duplication is usually a better investment than setting up a shared test fixture. <p> But if you must... <p> You can wrap the test suite containing all your tests in a subclass of <code>TestSetup</code> which invokes <code>setUp()</... [truncated message content] |