filtering by category can lead to ExceptionInInitializerError

[nkeywal]

I am testing the support of categories in maven/surefire.

In categories.Categories#shouldRun you end up calling Description#getTestClass to check the annotations.

This is implemented by a direct classForName(className). This leads to a full initialization of this class (static & so on), even if at the end this test class won't be retained. As the initialization can be expensive for some categories of tests, it's already an issue.

In a context where there is a separation between the jvm used to select/launch the tests and the jvm used to execute them, it just does not work.

This can be very easily fixed in JUnit by not initializing the class in Description#getTestClass by calling
Class.forName(name, false, getClass().getClassLoader());

instead of

Class.forName(name);

This method exists since java 1.2 (see http://download.oracle.com/javase/6/docs/api/java/lang/Class.html#forName%28java.lang.String,%20boolean,%20java.lang.ClassLoader%29)

Tested, it works with maven/surefire.

[Tibor17]

I don't understand what ExceptionInInitializerError has to do with the JUnit in this case.
This exc is thrown because of fault in your code of static context.
Catch the cause of the exception and see what has really happened.

This would be safer:
Class.forName(name, false, Thread.currentThread().getContextClassLoader());

[nkeywal]

Thank for you answer.

Yeah, the initialization fails in our code. Some tests must be executed in an isolated JVM, and cannot be initialized in the same JVM. This works quite well with maven surefire, there is a specific parameter for this (forkMode=always).

But with categories, the selection in JUnit iterates on all the classes and initializes them to look for the meta-data (annotation & methods & so on). As it's not an isolated context if fails.

But JUnit does not need to fully initialize the class just to see if it has to be included. Not doing it prevents initialization conflict between class test categories and improve the performances as the initialization is not necessary if the test is not selected at the end. This is important when working with categories; you don't want to initialize the complex tests when you just want a quick run of the small tests category.

Yes, agreed on the class loader, the second method is better.

[marcphilipp]

Fixed by #362.