junit-platform-engine/src/main/java/org/junit/platform/engine/EngineDiscoveryRequest.java

@@ -18,6 +18,7 @@
 import org.apiguardian.api.API;
 import org.junit.platform.commons.JUnitException;
 import org.junit.platform.engine.reporting.OutputDirectoryProvider;
+import org.junit.platform.engine.support.store.NamespacedHierarchicalStore;
 
 /**
  * {@code EngineDiscoveryRequest} provides a {@link TestEngine} access to the
@@ -94,4 +95,7 @@ default OutputDirectoryProvider getOutputDirectoryProvider() {
 		throw new JUnitException(
 			"OutputDirectoryProvider not available; probably due to unaligned versions of the junit-platform-engine and junit-platform-launcher jars on the classpath/module path.");
 	}
+
+	@API(status = EXPERIMENTAL, since = "5.13")
+	NamespacedHierarchicalStore<Namespace> getStore();
 }

junit-platform-engine/src/main/java/org/junit/platform/engine/Namespace.java

@@ -71,7 +71,7 @@ public int hashCode() {
 	 * existing sequence of parts in this namespace.
 	 *
 	 * @return new namespace; never {@code null}
-	 * @since 5.8
+	 * @since 5.13
 	 */
 	@API(status = STABLE, since = "5.13")
 	public Namespace append(Object... parts) {
@@ -80,6 +80,6 @@ public Namespace append(Object... parts) {
 		ArrayList<Object> newParts = new ArrayList<>(this.parts.size() + parts.length);
 		newParts.addAll(this.parts);
 		Collections.addAll(newParts, parts);
-		return new Namespgitace(newParts);
+		return new Namespace(newParts);
 	}
 }

junit-platform-launcher/src/main/java/org/junit/platform/launcher/LauncherDiscoveryRequest.java

@@ -19,6 +19,8 @@
 import org.junit.platform.engine.DiscoveryFilter;
 import org.junit.platform.engine.DiscoverySelector;
 import org.junit.platform.engine.EngineDiscoveryRequest;
+import org.junit.platform.engine.Namespace;
+import org.junit.platform.engine.support.store.NamespacedHierarchicalStore;
 
 /**
  * {@code LauncherDiscoveryRequest} extends the {@link EngineDiscoveryRequest} API
@@ -96,4 +98,6 @@ default LauncherDiscoveryListener getDiscoveryListener() {
 		return LauncherDiscoveryListener.NOOP;
 	}
 
+	NamespacedHierarchicalStore<Namespace> getStore();
+
 }

junit-platform-launcher/src/main/java/org/junit/platform/launcher/core/DefaultDiscoveryRequest.java

@@ -20,7 +20,9 @@
 import org.junit.platform.engine.DiscoveryFilter;
 import org.junit.platform.engine.DiscoverySelector;
 import org.junit.platform.engine.EngineDiscoveryRequest;
+import org.junit.platform.engine.Namespace;
 import org.junit.platform.engine.reporting.OutputDirectoryProvider;
+import org.junit.platform.engine.support.store.NamespacedHierarchicalStore;
 import org.junit.platform.launcher.EngineFilter;
 import org.junit.platform.launcher.LauncherDiscoveryListener;
 import org.junit.platform.launcher.LauncherDiscoveryRequest;
@@ -54,14 +56,17 @@ final class DefaultDiscoveryRequest implements LauncherDiscoveryRequest {
 
 	private final OutputDirectoryProvider outputDirectoryProvider;
 
+	private final NamespacedHierarchicalStore<Namespace> store;
+
 	DefaultDiscoveryRequest(List<DiscoverySelector> selectors, List<EngineFilter> engineFilters,
 			List<DiscoveryFilter<?>> discoveryFilters, List<PostDiscoveryFilter> postDiscoveryFilters,
-			LauncherConfigurationParameters configurationParameters, LauncherDiscoveryListener discoveryListener,
-			OutputDirectoryProvider outputDirectoryProvider) {
+			NamespacedHierarchicalStore<Namespace> store, LauncherConfigurationParameters configurationParameters,
+			LauncherDiscoveryListener discoveryListener, OutputDirectoryProvider outputDirectoryProvider) {
 		this.selectors = selectors;
 		this.engineFilters = engineFilters;
 		this.discoveryFilters = discoveryFilters;
 		this.postDiscoveryFilters = postDiscoveryFilters;
+		this.store = store;
 		this.configurationParameters = configurationParameters;
 		this.discoveryListener = discoveryListener;
 		this.outputDirectoryProvider = outputDirectoryProvider;
@@ -99,6 +104,11 @@ public LauncherDiscoveryListener getDiscoveryListener() {
 		return this.discoveryListener;
 	}
 
+	@Override
+	public NamespacedHierarchicalStore<Namespace> getStore() {
+		return this.store;
+	}
+
 	@Override
 	public OutputDirectoryProvider getOutputDirectoryProvider() {
 		return this.outputDirectoryProvider;

junit-platform-launcher/src/main/java/org/junit/platform/launcher/core/LauncherDiscoveryRequestBuilder.java

@@ -29,7 +29,9 @@
 import org.junit.platform.engine.DiscoveryFilter;
 import org.junit.platform.engine.DiscoverySelector;
 import org.junit.platform.engine.Filter;
+import org.junit.platform.engine.Namespace;
 import org.junit.platform.engine.reporting.OutputDirectoryProvider;
+import org.junit.platform.engine.support.store.NamespacedHierarchicalStore;
 import org.junit.platform.launcher.EngineFilter;
 import org.junit.platform.launcher.LauncherConstants;
 import org.junit.platform.launcher.LauncherDiscoveryListener;
@@ -110,6 +112,8 @@ public final class LauncherDiscoveryRequestBuilder {
 	private final Map<String, String> configurationParameters = new HashMap<>();
 	private final List<String> configurationParametersResources = new ArrayList<>();
 	private final List<LauncherDiscoveryListener> discoveryListeners = new ArrayList<>();
+	// TODO[#4252] Use the session-level store as its parent.
+	private final NamespacedHierarchicalStore<Namespace> store = new NamespacedHierarchicalStore<>(null);
 	private boolean implicitConfigurationParametersEnabled = true;
 	private ConfigurationParameters parentConfigurationParameters;
 	private OutputDirectoryProvider outputDirectoryProvider;
@@ -336,7 +340,8 @@ public LauncherDiscoveryRequest build() {
 		LauncherDiscoveryListener discoveryListener = getLauncherDiscoveryListener(launcherConfigurationParameters);
 		OutputDirectoryProvider outputDirectoryProvider = getOutputDirectoryProvider(launcherConfigurationParameters);
 		return new DefaultDiscoveryRequest(this.selectors, this.engineFilters, this.discoveryFilters,
-			this.postDiscoveryFilters, launcherConfigurationParameters, discoveryListener, outputDirectoryProvider);
+			this.postDiscoveryFilters, this.store, launcherConfigurationParameters, discoveryListener,
+			outputDirectoryProvider);
 	}
 
 	private OutputDirectoryProvider getOutputDirectoryProvider(