Java™ Application Development on Linux - Dator

13.4 Installing and Running JUnit301The JDK installation directory has a subdirectory named jre/lib/ext.Don’t put the JUnit JAR file in there. If you have followed our instructions,you’re OK, since we had you create a new directory.To use JUnit, the junit.jar file needs to be in your classpath. Forexample:$ export CLASSPATH="${CLASSPATH}:${HOME}/junit/junit3.8.1/junit.jar"That’s all the installing there is. It doesn’t feel like much, because youhaven’t done much. All it provides is a JAR file that you will use when you wantto run tests. That’s where it gets interesting.13.4.2 Using JUnitTo test out your installation, cd to the directory where you unpacked JUnit.If it isn’t already part of it, add the current directory (“.”) to your CLASSPATH:$ export CLASSPATH="${CLASSPATH}:."Then try:$ java junit.swingui.TestRunner junit.samples.AllTestsYou should see a Java Swing GUI appear, with a green bar showing theprogress of the testing (Figure 13.3).NOTEYou may see an error message like this in your terminal window:(data/time) java.util.prefs.FileSystemPreferences checkLock...WARNING: Could not lock System prefs.Unix error code 136742412(data/time) java.util.prefs.FileSystemPreferences syncWorldWARNING: Couldn't flush system prefs: java.util.prefs.Backi...It will keep repeating as long as JUnit’s GUI is running. The easiest fix isto make the jre directory world-writable while you run the GUI the first time. Itwill create the files it needs (in a directory, .systemPrefs), and thereafterstop pestering you. Remember to change permissions on the directory back totheir original value.