How does Eclipse actually run Junit tests?

by

To answer your problem first, if you have a discrepancy between the Ant junit and Eclipse JUnit, it’s probably a classpath or environmental problem. The easiest way is to find a test that performs differently between the two and print out the System properties, and work at it from that direction. Another thing to try would be to run the ant scripts from within Eclipse, to see if this makes any difference (because the environment will change)

Eclipse does not use Ant to run the tests.

As for how Eclipse runs JUnit tests, here is a quick overview. Be warned: there is some deep magic in the Eclipse JUnit plugin.

Eclipse has 4 JUnit plugins, which are all installed by default in most configurations:

  1. org.eclipse.jdt.junit: git://dev.eclipse.org/org.eclipse.jdt/org.eclipse.jdt.junit.git
  2. org.eclipse.jdt.junit.core: git://dev.eclipse.org/org.eclipse.jdt/org.eclipse.jdt.junit.core.git
  3. org.eclipse.jdt.junit.runtime: git://dev.eclipse.org/org.eclipse.jdt/org.eclipse.jdt.junit.runtime.git
  4. org.eclipse.jdt.junit4.runtime: git://dev.eclipse.org/org.eclipse.jdt/org.eclipse.jdt.junit4.runtime.git

These are git mirrors of the actual CVS repositories. Last time I tried to use them, they didn’t compile, but they’ll give you the code and you can at least import the projects into Eclipse and look at them.

If we ignore the configuration pages, how the plugin creates run configurations, the code for the JUnit view itself and how it finds the relevant tests to run, we can concentrate on how it runs the tests.

The core classes are org.eclipse.jdt.junit.launcher.JUnitLaunchConfigurationDelegate and org.eclipse.jdt.internal.junit.runner.RemoteTestRunner. JUnitLaunchConfigurationDelegate reads the launch configuration and forks a JVM in which the tests will be run. The main class for this new JVM is RemoteTestRunner. The tests to be run are passed as parameters to the forked JVM, either as a single test or as a list of tests in a temporary file if you’re doing Run as JUnit on a project. If you’re debugging, this new JVM can be kept alive by checking the Keep alive when debugging checkbox in the run configuration. In this case, the JVM will stick around and reruns of existing tests will be sent via sockets.

RemoteTestRunner runs the tests and passes back the results via sockets to Eclipse, which then updates the JUnit view. The heart of this is org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference, which runs the test (for JUnit 4), and org.eclipse.jdt.internal.junit4.runner.JUnit4TestListener, which is the RunListener for these tests. JUnit4TestListener extends RunListener, but doesn’t override testAssumptionFailure, which is probably why your tests are passing in Eclipse. RunListener.testAssumptionFailure is an empty method, it does nothing, so your notifications will be ignored.

I would start by cloning the git repos, importing the projects into Eclipse and trying to work through the code.

More Related Contents:

  1. JUnit testing with simulated user input
  2. Easy way of running the same junit test over and over?
  3. java.lang.NoClassDefFoundError: org/hamcrest/SelfDescribing
  4. No tests found with test runner ‘JUnit 4’
  5. Eclipse – debugger doesn’t stop at breakpoint
  6. Eclipse No tests found using JUnit 5 caused by NoClassDefFoundError for LauncherFactory
  7. java.lang.NoClassDefFoundError in junit
  8. how to export (JUnit) test suite as executable jar
  9. Eclipse Java IDE JUnit5: junit.jupiter.api.Assertions is not accessible
  10. Using assertArrayEquals in unit tests
  11. I'm trying to create a basic android application on eclipse [closed]
  12. Why won’t eclipse oxygen start (for the first time)? [duplicate]
  13. Maven does not find JUnit tests to run
  14. org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 15
  15. Eclipse/Maven error: “No compiler is provided in this environment”
  16. Custom JUnit Report?
  17. Incompatible JVM in GGTS (Eclipse) and JAVA 1.8
  18. Android Geocoder getFromLocationName always returns null
  19. hamcrest tests always fail
  20. How do I run my application as superuser from Eclipse?
  21. Saving Logcat to a text file in Android Device
  22. Mocking Logger and LoggerFactory with PowerMock and Mockito
  23. Java 9 + maven + junit: does test code need module-info.java of its own and where to put it?
  24. How to add shortcut keys for java code in eclipse
  25. How to test main class of Spring-boot application
  26. Error when try install plugin
  27. m2Eclipse plugin: What does ‘Resolve Workspace Artifacts’ do?
  28. Powermock – java.lang.IllegalStateException: Failed to transform class
  29. Setting the correct PATH for Eclipse
  30. Why is Ant giving me a Unsupported major.minor version error

Leave a Comment