Eclipse JUnit 4 provides a NullPointerException

Question

When I try to run the JUnit 4 test, I get a NullPointerException in Eclipse. JUnit3 is working.

I am trying to execute the following test class:

import static org.junit.Assert.fail; import org.junit.Test; public class Test { @Test public void test() { fail("Not yet implemented"); } } 

Here is the exception stack trace:

 java.lang.NullPointerException at org.eclipse.jdt.junit.launcher.JUnitLaunchConfigurationDelegate$ClasspathLocalizer.localURL(JUnitLaunchConfigurationDelegate.java:420) at org.eclipse.jdt.junit.launcher.JUnitLaunchConfigurationDelegate$ClasspathLocalizer.entryString(JUnitLaunchConfigurationDelegate.java:409) at org.eclipse.jdt.junit.launcher.JUnitLaunchConfigurationDelegate$ClasspathLocalizer.addEntry(JUnitLaunchConfigurationDelegate.java:396) at org.eclipse.jdt.junit.launcher.JUnitLaunchConfigurationDelegate$ClasspathLocalizer.localizeClasspath(JUnitLaunchConfigurationDelegate.java:387) at org.eclipse.jdt.junit.launcher.JUnitLaunchConfigurationDelegate.getClasspath(JUnitLaunchConfigurationDelegate.java:364) at org.eclipse.jdt.junit.launcher.JUnitLaunchConfigurationDelegate.launch(JUnitLaunchConfigurationDelegate.java:147) at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:855) at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:704) at org.eclipse.debug.internal.ui.DebugUIPlugin.buildAndLaunch(DebugUIPlugin.java:1047) at org.eclipse.debug.internal.ui.DebugUIPlugin$8.run(DebugUIPlugin.java:1251) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53) 

I am using OS X Snow Leopard with Java SDK 1.6.0_35 (from Apple). Both JDK and JUnit 4 are in my build path. Does the Java version have anything to do with the problem?

UPDATE:

OK, I'm an idiot without thinking about it. I installed Eclipse for C / C ++ developers, as I had to do something in C ++. But I also used the same instance for Android for Android with the Android SDK plugin, and I made some small Java applications. But I did not have Java development tools or Java EE developer tools. I installed them now and JUnit 4 is working now.

I think one of these tools is used for JUnit 4. Strange though JUnit 3 worked. In any case, it works now.

Thank you all for your support.

Answer 1

OK, I'm an idiot without thinking about it. I installed Eclipse for C / C ++ developers, as I had to do something in C ++. But I also used the same instance for Android for Android with the Android SDK plugin, and I made some small Java applications. But I did not have Java development tools or Java EE developer tools. I installed them now and now JUnit 4 is working.

Answer 2

I have the same problems, I am reinstalling ADT from version 22.3 to 23 because there is an update problem. The new version of ADT seems to exclude the Java Development Tool.

You can check "Help" → "About" → "Installation Details" for details.

So, I use the existing Juno update site in eclipse to install JDT (Juno - http://download.eclipse.org/releases/juno ), after that it works fine.

Answer 3

Your org.junit.Test import causes a conflict with the class name. You might want to rename your class test, for example, ATest get:

 java.lang.AssertionError: Not yet implemented at org.junit.Assert.fail(Assert.java:91) at ATest.test(ATest.java:8) 

Another option might be to put Test in a package (so as not to use the default package)

Source:

 import static org.junit.Assert.fail; import org.junit.Test; public class ATest { @Test public void test() { fail("Not yet implemented"); } } 

Tested with Eclipse Juno on Max OS 10.8.0

 java version "1.6.0_35" Java(TM) SE Runtime Environment (build 1.6.0_35-b10-428-10M3811) Java HotSpot(TM) Client VM (build 20.10-b01-428, mixed mode) 

I am sure it will also work on the lion.

Answer 4

There is a solution, yes. As described in UPDATE, the default is JUnit 4, which is not installed. After upgrading to JUnit 3, it works.

Answer 5

I had the same issue with the recently installed Eclipse Neon, and with ADT (Android, which includes Java and usually installs Junit).

I just installed JDT (Java Development Tools) and it works well after.

Answer 6

I had the same problem! Just reset the perspective (right click → Reset) and it will work!