Suite.java

package org.junit.runners;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.util.HashSet;
import java.util.Set;

import org.junit.internal.runners.InitializationError;
import org.junit.internal.runners.MethodValidator;
import org.junit.internal.runners.TestClassRunner;
import org.junit.runner.Request;

/**
 * Using <code>Suite</code> as a runner allows you to manually
 * build a suite containing tests from many classes. It is the JUnit 4 equivalent of the JUnit 3.8.x
 * static {@link junit.framework.Test} <code>suite()</code> method. To use it, annotate a class
 * with <code>@RunWith(Suite.class)</code> and <code>@SuiteClasses(TestClass1.class, ...)</code>.
 * When you run this class, it will run all the tests in all the suite classes.
 */
public class Suite extends TestClassRunner {
	/**
	 * The <code>SuiteClasses</code> annotation specifies the classes to be run when a class
	 * annotated with <code>@RunWith(Suite.class)</code> is run.
	 */
	@Retention(RetentionPolicy.RUNTIME)
	@Target(ElementType.TYPE)
	public @interface SuiteClasses {
		public Class<?>[] value();
	}

	/**
	 * Internal use only.
	 */
	public Suite(Class<?> klass) throws InitializationError {
		this(klass, getAnnotatedClasses(klass));
	}

	// This won't work correctly in the face of concurrency. For that we need to
	// add parameters to getRunner(), which would be much more complicated.
	private static Set<Class<?>> parents = new HashSet<Class<?>>();
	
	private static Class<?> addParent(Class<?> parent) throws InitializationError {
		if (!parents.add(parent))
			throw new InitializationError(String.format("class '%s' (possibly indirectly) contains itself as a SuiteClass", parent.getName()));
		return parent;
	}
	
	protected Suite(Class<?> klass, Class<?>[] annotatedClasses) throws InitializationError {
		super(addParent(klass), Request.classes(klass.getName(), annotatedClasses).getRunner());
		parents.remove(klass);
	}

	private static Class<?>[] getAnnotatedClasses(Class<?> klass) throws InitializationError {
		SuiteClasses annotation= klass.getAnnotation(SuiteClasses.class);
		if (annotation == null)
			throw new InitializationError(String.format("class '%s' must have a SuiteClasses annotation", klass.getName()));
		return annotation.value();
	}
	
	@Override
	protected void validate(MethodValidator methodValidator) {
		methodValidator.validateStaticMethods();
		methodValidator.validateInstanceMethods();
	}
}