Sort entries by test attribute

Currently all entries are given in the insertion order, but for test
entries they should come last as they are only accessible in the test
code while other entries are accessible by both.

To prevent test entries from overriding regular ones, we sort them to be
placed later in the classpath.

Author: laeubi

ui/org.eclipse.pde.core/src/org/eclipse/pde/internal/core/RequiredPluginsClasspathContainer.java

@@ -21,6 +21,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -41,6 +42,7 @@
 import org.eclipse.core.runtime.IExtensionRegistry;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.Platform;
+import org.eclipse.jdt.core.IClasspathAttribute;
 import org.eclipse.jdt.core.IClasspathContainer;
 import org.eclipse.jdt.core.IClasspathEntry;
 import org.eclipse.jdt.core.JavaCore;
@@ -137,10 +139,25 @@ public IClasspathEntry[] getClasspathEntries() {
 					System.out.println("\t" + entry); //$NON-NLS-1$
 				}
 			}
+			// see for example
+			// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/4133
+			// we need to make sure that regular entries are before test
+			// entries, this is also the "natural" order of items in regular
+			// classpath
+			Arrays.sort(fEntries, Comparator.comparingInt(cpe -> isTestEntry(cpe) ? 1 : 0));
 		}
 		return fEntries;
 	}
 
+	private boolean isTestEntry(IClasspathEntry cpe) {
+		for (IClasspathAttribute attr : cpe.getExtraAttributes()) {
+			if (IClasspathAttribute.TEST.equals(attr.getName())) {
+				return Boolean.parseBoolean(attr.getValue());
+			}
+		}
+		return false;
+	}
+
 	private IClasspathEntry[] computePluginEntriesByProject() {
 		try {
 			Optional<Project> bndProject = BndProjectManager.getBndProject(project);