Add support for deterministic testing with JUnit

naver · Jan 18, 2025 · 9f8474a · 9f8474a
1 parent 7a67237
commit 9f8474a
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Showing 4 changed files with 84 additions and 36 deletions.
diff --git a/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/random/Randoms.java b/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/random/Randoms.java
@@ -18,14 +18,12 @@
 
 package com.navercorp.fixturemonkey.api.random;
 
-import java.util.Random;
-
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+import net.jqwik.engine.SourceOfRandomness;
 import org.apiguardian.api.API;
 import org.apiguardian.api.API.Status;
 
-import net.jqwik.engine.SourceOfRandomness;
-
-import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+import java.util.Random;
 
 /**
  * Reference jqwik SourceOfRandomness
@@ -47,7 +45,7 @@ public abstract class Randoms {
 		}
 		USE_JQWIK_ENGINE = useJqwikEngine;
 		SEED = ThreadLocal.withInitial(System::nanoTime);
-		CURRENT = ThreadLocal.withInitial(() -> Randoms.create(SEED.get()));
+		CURRENT = ThreadLocal.withInitial(() -> Randoms.newGlobalSeed(SEED.get()));
 	}
 
 	/**
@@ -60,10 +58,30 @@ public static Random create(String seed) {
 		return CURRENT.get();
 	}
 
+	/**
+	 * sets the initialized seed value.
+	 * If the seed has been initialized, it will no longer be changed.
+	 *
+	 * @param seed the seed value
+	 */
 	public static void setSeed(long seed) {
 		SEED.set(seed);
 	}
 
+	/**
+	 * Creates a new random instance with the given seed.
+	 * It affects the global seed value across multiple FixtureMonkey instances.
+	 * It is not recommended to use this method directly unless you intend to.
+	 * It is generally recommended to use {@link #setSeed(long)} instead.
+	 *
+	 * @param seed the seed value
+	 * @return a new random instance
+	 */
+	public static Random newGlobalSeed(long seed) {
+		initializeGlobalSeed(seed);
+		return CURRENT.get();
+	}
+
 	public static Random current() {
 		return USE_JQWIK_ENGINE
 			? SourceOfRandomness.current()
@@ -78,17 +96,24 @@ public static int nextInt(int bound) {
 		return current().nextInt(bound);
 	}
 
-	private static Random create(long seed) {
+	/**
+	 * Creates a new random instance with the given seed. It is not thread safe.
+	 * It is generally recommended to use {@link #setSeed(long)} instead.
+	 * It affects the global seed value across multiple FixtureMonkey instances.
+	 *
+	 * @param seed the seed value
+	 */
+	private static void initializeGlobalSeed(long seed) {
 		if (USE_JQWIK_ENGINE) {
 			SEED.set(seed);
-			return SourceOfRandomness.create(String.valueOf(seed));
+			Random random = SourceOfRandomness.create(String.valueOf(seed));
+			CURRENT.set(random);
 		}
 
 		try {
 			Random random = newRandom(seed);
 			CURRENT.set(random);
 			SEED.set(seed);
-			return random;
 		} catch (NumberFormatException nfe) {
 			throw new IllegalArgumentException(String.format("[%s] is not a valid random seed.", seed));
 		}
@@ -127,7 +152,7 @@ private XorShiftRandom(long seed) {
 		protected int next(int nbits) {
 			long value = nextLong();
 			value &= ((1L << nbits) - 1);
-			return (int)value;
+			return (int) value;
 		}
 
 		/**

diff --git a/fixture-monkey-junit-jupiter/build.gradle.kts b/fixture-monkey-junit-jupiter/build.gradle.kts
@@ -1,5 +1,5 @@
 plugins {
-    id("org.jetbrains.kotlin.jvm") 
+    id("org.jetbrains.kotlin.jvm")
     id("com.navercorp.fixturemonkey.gradle.plugin.java-conventions")
     id("com.navercorp.fixturemonkey.gradle.plugin.maven-publish-conventions")
 }
@@ -16,5 +16,7 @@ dependencies {
 }
 
 tasks.withType<Test> {
-    useJUnitPlatform()
+    useJUnitPlatform {
+        includeEngines("junit-jupiter")
+    }
 }
diff --git a/.../java/com/navercorp/fixturemonkey/junit/jupiter/extension/FixtureMonkeySeedExtension.java b/.../java/com/navercorp/fixturemonkey/junit/jupiter/extension/FixtureMonkeySeedExtension.java
@@ -17,26 +17,38 @@
  */
 package com.navercorp.fixturemonkey.junit.jupiter.extension;
 
-import java.lang.reflect.Method;
-
+import com.navercorp.fixturemonkey.api.random.Randoms;
+import com.navercorp.fixturemonkey.junit.jupiter.annotation.Seed;
 import org.junit.jupiter.api.extension.AfterTestExecutionCallback;
 import org.junit.jupiter.api.extension.BeforeTestExecutionCallback;
 import org.junit.jupiter.api.extension.ExtensionContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.navercorp.fixturemonkey.api.random.Randoms;
-import com.navercorp.fixturemonkey.junit.jupiter.annotation.Seed;
+import java.lang.reflect.Method;
 
+/**
+ * This extension sets the seed for generating random numbers before a test method is executed.
+ * It also logs the seed used for the test if the test fails.
+ * It aims to make the test deterministic and reproducible.
+ * <p>
+ * If the test method has a {@link Seed} annotation, it uses the value of the annotation as the seed.
+ * If the test method does not have a {@link Seed} annotation, it uses the hash code of the test method as the seed.
+ */
 public final class FixtureMonkeySeedExtension implements BeforeTestExecutionCallback, AfterTestExecutionCallback {
 	private static final Logger LOGGER = LoggerFactory.getLogger(FixtureMonkeySeedExtension.class);
 
 	@Override
-	public void beforeTestExecution(ExtensionContext context) throws Exception {
+	public void beforeTestExecution(ExtensionContext context) {
 		Seed seed = context.getRequiredTestMethod().getAnnotation(Seed.class);
 		if (seed != null) {
 			setSeed(seed.value());
+			return;
 		}
+
+		Method testMethod = context.getRequiredTestMethod();
+		int methodHashCode = testMethod.hashCode();
+		setSeed(methodHashCode);
 	}
 
 	/**
@@ -45,7 +57,7 @@ public void beforeTestExecution(ExtensionContext context) throws Exception {
 	 * If the test failed, it logs the seed used for the test.
 	 **/
 	@Override
-	public void afterTestExecution(ExtensionContext context) throws Exception {
+	public void afterTestExecution(ExtensionContext context) {
 		if (context.getExecutionException().isPresent()) {
 			logSeedIfTestFailed(context);
 		}
@@ -55,7 +67,7 @@ public void afterTestExecution(ExtensionContext context) throws Exception {
 	 * Sets the seed for generating random numbers.
 	 **/
 	private void setSeed(long seed) {
-		Randoms.setSeed(seed);
+		Randoms.newGlobalSeed(seed);
 	}
 
 	/**

diff --git a/...a/com/navercorp/fixturemonkey/junit/jupiter/extension/FixtureMonkeySeedExtensionTest.java b/...a/com/navercorp/fixturemonkey/junit/jupiter/extension/FixtureMonkeySeedExtensionTest.java
@@ -17,19 +17,15 @@
  */
 package com.navercorp.fixturemonkey.junit.jupiter.extension;
 
-import static org.assertj.core.api.BDDAssertions.then;
-
-import java.util.Arrays;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
-
-import org.junit.jupiter.api.RepeatedTest;
-import org.junit.jupiter.api.extension.ExtendWith;
-
 import com.navercorp.fixturemonkey.FixtureMonkey;
 import com.navercorp.fixturemonkey.api.type.TypeReference;
 import com.navercorp.fixturemonkey.junit.jupiter.annotation.Seed;
+import org.junit.jupiter.api.RepeatedTest;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import java.util.*;
+
+import static org.assertj.core.api.BDDAssertions.then;
 
 @ExtendWith(FixtureMonkeySeedExtension.class)
 class FixtureMonkeySeedExtensionTest {
@@ -59,10 +55,7 @@ void latterValue() {
 	@Seed(1)
 	@RepeatedTest(100)
 	void containerReturnsSame() {
-		List<String> expected = Arrays.asList(
-			"仛禦催ᘓ蓊類౺阹瞻塢飖獾ࠒ⒐፨婵얎⽒竻·俌欕悳잸횑ٻ킐結",
-			"塸聩ዡ㘇뵥刲禮ᣮ鎊熇捺셾壍Ꜻꌩ垅凗❉償粐믩࠱哠"
-		);
+		List<String> expected = Collections.singletonList("仛禦催ᘓ蓊類౺阹瞻塢飖獾ࠒ⒐፨婵얎⽒竻·俌欕悳잸횑ٻ킐結");
 
 		List<String> actual = SUT.giveMeOne(new TypeReference<List<String>>() {
 		});
@@ -73,9 +66,7 @@ void containerReturnsSame() {
 	@Seed(1)
 	@RepeatedTest(100)
 	void containerMattersOrder() {
-		Set<String> expected = new HashSet<>(
-			Arrays.asList("仛禦催ᘓ蓊類౺阹瞻塢飖獾ࠒ⒐፨婵얎⽒竻·俌欕悳잸횑ٻ킐結", "塸聩ዡ㘇뵥刲禮ᣮ鎊熇捺셾壍Ꜻꌩ垅凗❉償粐믩࠱哠")
-		);
+		Set<String> expected = new HashSet<>(Collections.singletonList("仛禦催ᘓ蓊類౺阹瞻塢飖獾ࠒ⒐፨婵얎⽒竻·俌欕悳잸횑ٻ킐結"));
 
 		Set<String> actual = SUT.giveMeOne(new TypeReference<Set<String>>() {
 		});
@@ -94,4 +85,22 @@ void multipleContainerReturnsDiff() {
 
 		then(firstSet).isNotEqualTo(secondList);
 	}
+
+	@Seed(1)
+	@RepeatedTest(100)
+	void multipleFixtureMonkeyInstancesReturnsAsOneInstance() {
+		List<String> expected = Arrays.asList(
+			"✠섨ꝓ仛禦催ᘓ蓊類౺阹瞻塢飖獾ࠒ⒐፨",
+			"欕悳잸"
+		);
+		FixtureMonkey firstFixtureMonkey = FixtureMonkey.create();
+		FixtureMonkey secondFixtureMonkey = FixtureMonkey.create();
+
+		List<String> actual = Arrays.asList(
+			firstFixtureMonkey.giveMeOne(String.class),
+			secondFixtureMonkey.giveMeOne(String.class)
+		);
+
+		then(actual).isEqualTo(expected);
+	}
 }