Use same default seed for method and class ordering

Prior to this commit the default seeds were generated separately but the
configuration parameter that allows using a fixed seed only allowed to
set both to the same value making it impossible to reproduce a failure
for different default seeds. Since the default seed is now identical,
this scenario is avoided.

Fixes #3817.

junit-jupiter-api/src/main/java/org/junit/jupiter/api/ClassOrderer.java

@@ -185,8 +185,8 @@ private static int getOrder(ClassDescriptor descriptor) {
 	 * <h2>Custom Seed</h2>
 	 *
 	 * <p>By default, the random <em>seed</em> used for ordering classes is the
-	 * value returned by {@link System#nanoTime()} during static initialization
-	 * of this class. In order to support repeatable builds, the value of the
+	 * value returned by {@link System#nanoTime()} during static class
+	 * initialization. In order to support repeatable builds, the value of the
 	 * default random seed is logged at {@code CONFIG} level. In addition, a
 	 * custom seed (potentially the default seed from the previous test plan
 	 * execution) may be specified via the {@value Random#RANDOM_SEED_PROPERTY_NAME}
@@ -203,13 +203,12 @@ class Random implements ClassOrderer {
 		private static final Logger logger = LoggerFactory.getLogger(Random.class);
 
 		/**
-		 * Default seed, which is generated during initialization of this class
-		 * via {@link System#nanoTime()} for reproducibility of tests.
+		 * Default seed, which is generated during initialization of the
+		 * {@link MethodOrderer.Random} class for reproducibility of tests.
 		 */
-		private static final long DEFAULT_SEED;
+		static final long DEFAULT_SEED = MethodOrderer.Random.DEFAULT_SEED;
 
 		static {
-			DEFAULT_SEED = System.nanoTime();
 			logger.config(() -> "ClassOrderer.Random default seed: " + DEFAULT_SEED);
 		}
 

junit-jupiter-api/src/main/java/org/junit/jupiter/api/MethodOrderer.java

@@ -269,7 +269,7 @@ class Random implements MethodOrderer {
 		 * Default seed, which is generated during initialization of this class
 		 * via {@link System#nanoTime()} for reproducibility of tests.
 		 */
-		private static final long DEFAULT_SEED;
+		static final long DEFAULT_SEED;
 
 		static {
 			DEFAULT_SEED = System.nanoTime();

junit-jupiter-engine/src/test/java/org/junit/jupiter/engine/extension/RandomlyOrderedTests.java → junit-jupiter-engine/src/test/java/org/junit/jupiter/api/RandomlyOrderedTests.java

@@ -8,23 +8,20 @@
  * https://www.eclipse.org/legal/epl-v20.html
  */
 
-package org.junit.jupiter.engine.extension;
+package org.junit.jupiter.api;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.engine.Constants.DEFAULT_TEST_CLASS_ORDER_PROPERTY_NAME;
 import static org.junit.jupiter.engine.Constants.DEFAULT_TEST_METHOD_ORDER_PROPERTY_NAME;
 import static org.junit.platform.engine.discovery.DiscoverySelectors.selectClass;
 
 import java.util.Collections;
 import java.util.LinkedHashSet;
+import java.util.OptionalLong;
 import java.util.Set;
 import java.util.stream.IntStream;
 
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.ClassOrderer;
-import org.junit.jupiter.api.MethodOrderer;
-import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.TestInfo;
 import org.junit.platform.testkit.engine.EngineTestKit;
 import org.junit.platform.testkit.engine.Events;
 
@@ -39,21 +36,29 @@ class RandomlyOrderedTests {
 	void randomSeedForClassAndMethodOrderingIsDeterministic() {
 		IntStream.range(0, 20).forEach(i -> {
 			callSequence.clear();
-			var tests = executeTests(1618034L);
+			var tests = executeTests(OptionalLong.of(1618034));
 
 			tests.assertStatistics(stats -> stats.succeeded(callSequence.size()));
 			assertThat(callSequence).containsExactlyInAnyOrder("B_TestCase#b", "B_TestCase#c", "B_TestCase#a",
 				"C_TestCase#b", "C_TestCase#c", "C_TestCase#a", "A_TestCase#b", "A_TestCase#c", "A_TestCase#a");
 		});
 	}
 
-	private Events executeTests(long randomSeed) {
+	@Test
+	void defaultSeedForClassAndMethodOrderingIsIdentical() {
+		executeTests(OptionalLong.empty());
+
+		assertEquals(MethodOrderer.Random.DEFAULT_SEED, ClassOrderer.Random.DEFAULT_SEED);
+	}
+
+	private Events executeTests(@SuppressWarnings("OptionalUsedAsFieldOrParameterType") OptionalLong randomSeed) {
 		// @formatter:off
-		return EngineTestKit
+		EngineTestKit.Builder builder = EngineTestKit
 				.engine("junit-jupiter")
 				.configurationParameter(DEFAULT_TEST_CLASS_ORDER_PROPERTY_NAME, ClassOrderer.Random.class.getName())
-				.configurationParameter(DEFAULT_TEST_METHOD_ORDER_PROPERTY_NAME, MethodOrderer.Random.class.getName())
-				.configurationParameter(MethodOrderer.Random.RANDOM_SEED_PROPERTY_NAME, String.valueOf(randomSeed))
+				.configurationParameter(DEFAULT_TEST_METHOD_ORDER_PROPERTY_NAME, MethodOrderer.Random.class.getName());
+		randomSeed.ifPresent(seed -> builder.configurationParameter(MethodOrderer.Random.RANDOM_SEED_PROPERTY_NAME, String.valueOf(seed)));
+		return builder
 				.selectors(selectClass(A_TestCase.class), selectClass(B_TestCase.class), selectClass(C_TestCase.class))
 				.execute()
 				.testEvents();