Re-add JUnit 4 to org.eclipse.pde.core.requiredPlugins

Due to changes for #2007, the container org.eclipse.pde.core.requiredPlugins is now missing JUnit 4.

This change re-adds JUnit 4 to this container.

Fixes: #2020

Author: trancexpress

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

@@ -24,13 +24,15 @@
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Queue;
 import java.util.Set;
 import java.util.TreeMap;
+import java.util.function.Function;
 import java.util.stream.Stream;
 
 import org.eclipse.core.resources.IFile;
@@ -79,6 +81,8 @@ class RequiredPluginsClasspathContainer {
 	private static final Version JUNIT_5_9 = new Version(5, 9, 0);
 	private static final VersionRange BELOW_JUNIT_5_9 = new VersionRange("[1.0,5.9)"); //$NON-NLS-1$
 
+	@SuppressWarnings("nls")
+	private static final Set<String> JUNIT4_PLUGINS = Set.of("org.junit");
 	@SuppressWarnings("nls")
 	private static final Set<String> JUNIT5_RUNTIME_PLUGINS = Set.of("org.junit", //
 			"junit-platform-launcher",
@@ -594,7 +598,11 @@ private void addJunit5RuntimeDependencies(Set<BundleDescription> added, List<ICl
 			// JUnit 5.8 and below bundles don't have specific version requirements that we can use
 			junitRequirements = collectRuntimeRequirementsBelowJunit5_9();
 		} else {
-			junitRequirements = DependencyManager.findRequirementsClosure(List.of(junitBundle));
+			junitRequirements = new LinkedHashSet<>();
+			List<BundleDescription> junit4Requirements = collectRuntimeRequirements(JUNIT4_PLUGINS, PluginRegistry::findModel);
+			junitRequirements.addAll(junit4Requirements);
+			List<BundleDescription> junit5AndAboveRequirements = collectRuntimeRequirements(List.of(junitBundle));
+			junitRequirements.addAll(junit5AndAboveRequirements);
 		}
 		if (junitRequirements.isEmpty()) {
 			return;
@@ -617,11 +625,17 @@ private void addJunit5RuntimeDependencies(Set<BundleDescription> added, List<ICl
 	}
 
 	private static List<BundleDescription> collectRuntimeRequirementsBelowJunit5_9() {
-		List<BundleDescription> roots = JUNIT5_RUNTIME_PLUGINS.stream()
-				.map(id -> PluginRegistry.findModel(id, BELOW_JUNIT_5_9)).filter(Objects::nonNull)
+		return collectRuntimeRequirements(JUNIT5_RUNTIME_PLUGINS, id -> PluginRegistry.findModel(id, BELOW_JUNIT_5_9));
+	}
+
+	private static List<BundleDescription> collectRuntimeRequirements(Collection<String> bundleIds, Function<String, IPluginModelBase> findModel) {
+		List<BundleDescription> roots = bundleIds.stream().map(findModel).filter(Objects::nonNull)
 				.filter(IPluginModelBase::isEnabled).map(IPluginModelBase::getBundleDescription).toList();
-		Set<BundleDescription> closure = DependencyManager.findRequirementsClosure(roots,
-				INCLUDE_OPTIONAL_DEPENDENCIES);
+		return collectRuntimeRequirements(roots);
+	}
+
+	private static List<BundleDescription> collectRuntimeRequirements(List<BundleDescription> roots) {
+		Set<BundleDescription> closure = DependencyManager.findRequirementsClosure(roots, INCLUDE_OPTIONAL_DEPENDENCIES);
 		String systemBundleBSN = TargetPlatformHelper.getPDEState().getSystemBundle();
 		return closure.stream().filter(b -> !b.getSymbolicName().equals(systemBundleBSN))
 				.sorted(Comparator.comparing(BundleDescription::getSymbolicName)).toList();