Handle classes with empty names (e.g. anonymous classes)

Fixes #87.

src/main/java/org/junit/support/testng/engine/ClassDescriptor.java

@@ -40,11 +40,16 @@ class ClassDescriptor extends AbstractTestDescriptor {
 	ExecutionStrategy executionStrategy = new IncludeMethodsExecutionStrategy();
 
 	ClassDescriptor(UniqueId uniqueId, Class<?> testClass, Set<TestTag> tags) {
-		super(uniqueId, testClass.getSimpleName(), ClassSource.from(testClass));
+		super(uniqueId, determineDisplayName(testClass), ClassSource.from(testClass));
 		this.testClass = testClass;
 		this.tags = tags;
 	}
 
+	private static String determineDisplayName(Class<?> testClass) {
+		String simpleName = testClass.getSimpleName();
+		return simpleName.isEmpty() ? testClass.getName() : simpleName;
+	}
+
 	@Override
 	public String getLegacyReportingName() {
 		return testClass.getName();

src/test/java/org/junit/support/testng/engine/DiscoveryIntegrationTests.java

@@ -27,6 +27,7 @@
 import java.util.Map;
 import java.util.regex.Pattern;
 
+import example.basics.AnonymousClassTestCase;
 import example.basics.DryRunTestCase;
 import example.basics.IgnoredTestCase;
 import example.basics.InheritedClassLevelOnlyAnnotationTestCase;
@@ -314,6 +315,17 @@ void discoversNestedTestClasses() {
 		assertThat(classDescriptor.getChildren()).hasSize(1);
 	}
 
+	@Test
+	void ignoresAnonymousClasses() {
+		var selectedTestClass = AnonymousClassTestCase.class.getName() + "$1";
+		var request = request().selectors(selectClass(selectedTestClass)).build();
+
+		var rootDescriptor = testEngine.discover(request, engineId);
+
+		assertThat(rootDescriptor.getUniqueId()).isEqualTo(engineId);
+		assertThat(rootDescriptor.getChildren()).isEmpty();
+	}
+
 	interface InterfaceTestCase {
 	}
 

src/testFixtures/java/example/basics/AnonymousClassTestCase.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package example.basics;
+
+import org.testng.annotations.Test;
+
+public class AnonymousClassTestCase {
+
+	@Test
+	public void test() {
+		new AnonymousClassTestCase() {
+			@SuppressWarnings("unused")
+			@Test
+			public void method() {
+			}
+		};
+	}
+}