running a subset of JUnit @Test methods

guerda's solution is good. Here's what I ended up doing (it's a mix of Luke Francl's recipe, which I linked before, and some other stuff I saw on the net):

import org.junit.runner.manipulation.Filter;
import org.junit.runner.Description;

public final class AntCLFilter extends Filter {
    private static final String TEST_CASES = "tests";
    private static final String ANT_PROPERTY = "${tests}";
    private static final String DELIMITER = "\\,";
    private String[] testCaseNames;

    public AntCLFilter() {
        super();
        if (hasTestCases()) testCaseNames = getTestCaseNames();
    }

    public String describe() {
        return "Filters out all tests not explicitly named in a comma-delimited list in the system property 'tests'.";
    }

    public boolean shouldRun(Description d) {
        String displayName = d.getDisplayName();
        // cut off the method name:
        String testName = displayName.substring(0, displayName.indexOf('('));
        if (testCaseNames == null) return true;

        for (int i = 0; i < testCaseNames.length; i++)
            if (testName.equals(testCaseNames[i]))
                return true;
        return false;
    }

    /**
     * Check to see if the test cases property is set. Ignores Ant's
     * default setting for the property (or null to be on the safe side).
     **/
    public static boolean hasTestCases() {
        return
            System.getProperty( TEST_CASES ) == null ||
            System.getProperty( TEST_CASES ).equals( ANT_PROPERTY ) ?
            false : true;
    }

    /**
     * Create a List of String names of test cases specified in the
     * JVM property in comma-separated format.
     *
     * @return a List of String test case names
     *
     * @throws NullPointerException if the TEST_CASES property
     * isn't set
     **/
    private static String[] getTestCaseNames() {

        if ( System.getProperty( TEST_CASES ) == null ) {
            throw new NullPointerException( "Test case property is not set" );
        }

        String testCases = System.getProperty( TEST_CASES );
        String[] cases = testCases.split(DELIMITER);

        return cases;
    }
}

import org.junit.internal.runners.*;
import org.junit.runner.manipulation.Filter;
import org.junit.runner.manipulation.NoTestsRemainException;

public class FilteredRunner extends TestClassRunner {

    public FilteredRunner(Class<?> clazz) throws InitializationError {
        super(clazz);
        Filter f = new AntCLFilter();
        try {
            f.apply(this);
        } catch (NoTestsRemainException ex) {
            throw new RuntimeException(ex);
        }
    }
}

Then I annotated my test class with:

@RunWith(FilteredRunner.class)
public class MyTest {

and put the following in my ant buildfile:

<target name="runtest"
        description="Runs the test you specify on the command line with -Dtest="
        depends="compile, ensure-test-name">
    <junit printsummary="withOutAndErr" fork="yes">
        <sysproperty key="tests" value="${tests}" />
        <classpath refid="classpath" />
        <formatter type="plain" usefile="false" />
        <batchtest>
            <fileset dir="${src}">
                <include name="**/${test}.java" />
            </fileset>
        </batchtest>
    </junit>
</target>

the key line there being the sysproperty tag.

And now I can run

ant runtest -Dtest=MyTest -Dtests=testFoo,testBar

as desired. This works with JUnit 4.1 --- in 4.4, subclass from JUnit4ClassRunner, and in 4.5 and later, subclass from BlockJUnit4ClassRunner.

Create your own TestClassMethodsRunner (it's not documentated or I don't find it now).
A TestClassMethodsRunner executes all TestCases and you can set up a filtered TestClassMethodsRunner.

All you have to do is override the TestMethodRunner createMethodRunner(Object, Method, RunNotifier) method. This is a simple an hacky solution:

public class FilteredTestRunner extends TestClassMethodsRunner {

    public FilteredTestRunner(Class<?> aClass) {
        super(aClass);
    }

    @Override
    protected TestMethodRunner createMethodRunner(Object aTest, Method aMethod, RunNotifier aNotifier) {
        if (aTest.getClass().getName().contains("NOT")) {
            return new TestMethodRunner(aTest, aMethod, aNotifier, null) {
                @Override
                public void run() {
                    //do nothing with this test.
                }
            };
        } else {
            return super.createMethodRunner(aTest, aMethod, aNotifier);
        }
    }

}

With this TestRunner, you execute all Tests that don't contain the string "NOT". Others will be ignored :) Just add the @RunWith annotation with your TestRunner class to your test.

@RunWith(FilteredTestRunner.class)
public class ThisTestsWillNOTBeExecuted {
   //No test is executed.
}

@RunWith(FilteredTestRunner.class)
public class ThisTestsWillBeExecuted {
   //All tests are executed.
}

In the createMethodRunner method you can check the current test against a list of tests that must be executed or introduce new criterias.

Good luck with this!

Hints for a nicer solution are appreciated!

Since JUnit 4.12 we have @Category annotations to solve just that problem.

There is a simpler way for the common case where you need to run only one test method, without having to go through the hassle of creating a custom Runner or Filter:

public class MyTestClass {

  public static void main(final String[] args) throws Exception {
    final JUnitCore junit = new JUnitCore();
    final String singleTest = // Get the name of test from somewhere (environment, system property, whatever you want).
    final Request req;
    if (singleTest != null) {
      req = Request.method(MyTestClass.class, singleTest);
    } else {
      req = Request.aClass(MyTestClass.class);
    }
    final Result result = junit.run(req);
    // Check result.getFailures etc.
    if (!result.wasSuccessful()) {
      System.exit(1);
    }
  }

  // Your @Test methods here.

}