Bug 41798 New JUnit Plug-in test requires test suites to extend Test
The new JUnit plug-in test seems to require test suites to extend TestSuite. Otherwise an error is reported in the launch config dialog. It is however still possible to launch a test suite by opening it in the editor and choosing Run->Run As->New JUnit Plug-in Test To reproduce, try to run (and configure) the JDT UI AllAllTests testsuite.
org.eclipse.jdt.junit.core/src/org/eclipse/jdt/internal/junit/util/TestSearchEngine.java
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 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
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 * http://www.eclipse.org/legal/cpl-v10.html
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 * Contributors:
 *     IBM Corporation - initial API and implementation
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package org.eclipse.jdt.internal.junit.util;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.SubProgressMonitor;
import org.eclipse.jface.operation.IRunnableContext;
import org.eclipse.jface.operation.IRunnableWithProgress;
import org.eclipse.ui.IFileEditorInput;
import org.eclipse.jdt.core.Flags;
import org.eclipse.jdt.core.IClassFile;
import org.eclipse.jdt.core.ICompilationUnit;