build: migrate tests from JUnit 4 to JUnit 6

build-logic/src/main/kotlin/gestalt-library-common.gradle.kts

@@ -27,7 +27,7 @@ extensions.configure<ru.vyarus.gradle.plugin.animalsniffer.AnimalSnifferExtensio
 
 // Extra details provided for unit tests
 tasks.withType<Test> {
-    useJUnit()
+    useJUnitPlatform()
 
     // ignoreFailures: Specifies whether the build should break when the verifications performed by this task fail.
     ignoreFailures = true

gestalt-android-testbed/build.gradle

@@ -20,6 +20,11 @@ android {
         sourceCompatibility JavaVersion.VERSION_17
         targetCompatibility JavaVersion.VERSION_17
     }
+    testOptions {
+        unitTests.all {
+            it.useJUnitPlatform()
+        }
+    }
     packagingOptions {
         merge "META-INF/annotations/*"
     }
@@ -45,7 +50,10 @@ dependencies {
     implementation(libs.slf4j.api)
     implementation("com.github.tony19:logback-android:1.3.0-3")
     implementation(project(":testpack:testpack-api"))
-    testImplementation(libs.junit)
+    testImplementation(libs.junit.jupiter.api)
+    testRuntimeOnly(libs.junit.jupiter.engine)
+    testRuntimeOnly(libs.junit.platform.launcher)
+    // androidTest runs on-device via AndroidJUnitRunner, which is JUnit4-only - not migrated.
     androidTestImplementation("androidx.test:runner:1.6.2")
     androidTestImplementation("androidx.test.ext:junit:1.2.1")
     androidTestImplementation("androidx.test.espresso:espresso-core:3.6.1")

gestalt-android-testbed/src/test/java/org/terasology/gestalt/android/testbed/ExampleUnitTest.java

@@ -16,9 +16,9 @@
 
 package org.terasology.gestalt.android.testbed;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 /**
  * Example local unit test, which will execute on the development machine (host).

gestalt-android/build.gradle

@@ -51,7 +51,6 @@ dependencies {
     implementation(libs.guava)
 
     implementation("androidx.appcompat:appcompat:1.7.0")
-    testImplementation(libs.junit)
     androidTestImplementation("androidx.test:runner:1.6.2")
     androidTestImplementation("androidx.test.espresso:espresso-core:3.6.1")
 

gestalt-asset-core/build.gradle.kts

@@ -17,7 +17,9 @@ dependencies {
     api(libs.jcip)
 
     testAnnotationProcessor(project(":gestalt-inject-java"))
-    testImplementation(libs.junit)
+    testImplementation(libs.junit.jupiter.api)
+    testRuntimeOnly(libs.junit.jupiter.engine)
+    testRuntimeOnly(libs.junit.platform.launcher)
     testImplementation(libs.logback)
     testImplementation(libs.mockito)
 }

gestalt-asset-core/gradle.lockfile

@@ -17,18 +17,25 @@ com.googlecode.gentyref:gentyref:1.2.0=annotationProcessor,runtimeClasspath,test
 com.squareup:javapoet:1.13.0=annotationProcessor,testAnnotationProcessor
 com.toasttab.android:gummy-bears-api-24:0.15.0=signature
 javax.inject:javax.inject:1=annotationProcessor,compileClasspath,runtimeClasspath,testAnnotationProcessor,testCompileClasspath,testRuntimeClasspath
-junit:junit:4.12=testCompileClasspath,testRuntimeClasspath
 net.bytebuddy:byte-buddy-agent:1.17.7=testCompileClasspath,testRuntimeClasspath
 net.bytebuddy:byte-buddy:1.17.7=testCompileClasspath,testRuntimeClasspath
 net.jcip:jcip-annotations:1.0=compileClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
+org.apiguardian:apiguardian-api:1.1.2=testCompileClasspath
 org.checkerframework:checker-compat-qual:2.5.2=annotationProcessor,compileClasspath,runtimeClasspath,testAnnotationProcessor,testCompileClasspath,testRuntimeClasspath
 org.codehaus.mojo:animal-sniffer-annotations:1.17=annotationProcessor,compileClasspath,runtimeClasspath,testAnnotationProcessor,testCompileClasspath,testRuntimeClasspath
 org.codehaus.mojo:animal-sniffer-annotations:1.24=animalsniffer
 org.codehaus.mojo:animal-sniffer:1.24=animalsniffer
-org.hamcrest:hamcrest-core:1.3=testCompileClasspath,testRuntimeClasspath
 org.javassist:javassist:3.27.0-GA=runtimeClasspath,testRuntimeClasspath
+org.jspecify:jspecify:1.0.0=testCompileClasspath
+org.junit.jupiter:junit-jupiter-api:6.1.3=testCompileClasspath,testRuntimeClasspath
+org.junit.jupiter:junit-jupiter-engine:6.1.3=testRuntimeClasspath
+org.junit.platform:junit-platform-commons:6.1.3=testCompileClasspath,testRuntimeClasspath
+org.junit.platform:junit-platform-engine:6.1.3=testRuntimeClasspath
+org.junit.platform:junit-platform-launcher:6.1.3=testRuntimeClasspath
+org.junit:junit-bom:6.1.3=testCompileClasspath,testRuntimeClasspath
 org.mockito:mockito-core:5.23.0=testCompileClasspath,testRuntimeClasspath
 org.objenesis:objenesis:3.3=testRuntimeClasspath
+org.opentest4j:opentest4j:1.3.0=testCompileClasspath,testRuntimeClasspath
 org.ow2.asm:asm:9.7=animalsniffer
 org.slf4j:slf4j-api:1.7.25=annotationProcessor,compileClasspath,runtimeClasspath,testAnnotationProcessor,testCompileClasspath,testRuntimeClasspath
 empty=

gestalt-asset-core/src/test/java/org/terasology/gestalt/assets/AbstractFragmentProducerTest.java

@@ -19,7 +19,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.terasology.gestalt.assets.management.AssetManager;
 import org.terasology.gestalt.assets.management.AssetTypeManager;
 
@@ -33,8 +33,8 @@
 import virtualModules.test.stubs.text.TextData;
 import virtualModules.test.stubs.text.TextFactory;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 

gestalt-asset-core/src/test/java/org/terasology/gestalt/assets/AssetManagerTest.java

@@ -18,7 +18,7 @@
 
 import com.google.common.collect.ImmutableSet;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.terasology.gestalt.assets.management.AssetManager;
 import org.terasology.gestalt.assets.management.Context;
 import org.terasology.gestalt.assets.management.ContextManager;
@@ -37,9 +37,9 @@
 import virtualModules.test.stubs.text.TextData;
 import virtualModules.test.stubs.text.TextFactory;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;

gestalt-asset-core/src/test/java/org/terasology/gestalt/assets/AssetTypeTest.java

@@ -18,7 +18,7 @@
 
 import com.google.common.collect.ImmutableSet;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.terasology.gestalt.naming.Name;
 
 import java.io.IOException;
@@ -29,11 +29,11 @@
 import virtualModules.test.stubs.text.TextData;
 import virtualModules.test.stubs.text.TextFactory;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotSame;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;

gestalt-asset-core/src/test/java/org/terasology/gestalt/assets/ResourceUrnTest.java

@@ -16,14 +16,15 @@
 
 package org.terasology.gestalt.assets;
 
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
 import org.terasology.gestalt.assets.exceptions.InvalidUrnException;
 import org.terasology.gestalt.naming.Name;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Immortius
@@ -42,7 +43,7 @@ public class ResourceUrnTest {
     @Test
     public void moduleAndResourceConstructor() {
         ResourceUrn urn = new ResourceUrn(TEST_MODULE, TEST_RESOURCE);
-        Assert.assertEquals(new Name(TEST_MODULE), urn.getModuleName());
+        Assertions.assertEquals(new Name(TEST_MODULE), urn.getModuleName());
         assertEquals(new Name(TEST_RESOURCE), urn.getResourceName());
         assertTrue(urn.getFragmentName().isEmpty());
         assertEquals(URN_STRING, urn.toString());
@@ -105,9 +106,9 @@ public void fragmentInstanceConstructor() {
         assertEquals(URN_FRAGMENT_INSTANCE_STRING, urn.toString());
     }
 
-    @Test(expected = InvalidUrnException.class)
+    @Test
     public void invalidUrnStringConstructor() {
-        new ResourceUrn("blerg");
+        assertThrows(InvalidUrnException.class, () -> new ResourceUrn("blerg"));
     }
 
     @Test

gestalt-asset-core/src/test/java/org/terasology/gestalt/assets/module/AssetFileDataProducerTest.java

@@ -16,7 +16,7 @@
 
 package org.terasology.gestalt.assets.module;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.terasology.gestalt.assets.ResourceUrn;
 import org.terasology.gestalt.assets.format.producer.AssetFileDataProducer;
 import org.terasology.gestalt.module.ModuleEnvironment;
@@ -30,9 +30,9 @@
 import virtualModules.test.stubs.text.TextFileFormat;
 import virtualModules.test.stubs.text.TextMetadataFileFormat;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Immortius

gestalt-asset-core/src/test/java/org/terasology/gestalt/assets/module/ModuleAwareAssetTypeManagerTest.java

@@ -16,7 +16,7 @@
 
 package org.terasology.gestalt.assets.module;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.terasology.gestalt.assets.AssetData;
 import org.terasology.gestalt.assets.AssetDataProducer;
 import org.terasology.gestalt.assets.AssetFactory;
@@ -41,9 +41,9 @@
 import virtualModules.test.stubs.text.TextData;
 import virtualModules.test.stubs.text.TextFactory;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 

gestalt-asset-core/src/test/java/org/terasology/gestalt/assets/module/ModuleDependencyResolutionStrategyTest.java

@@ -18,13 +18,13 @@
 
 import com.google.common.collect.ImmutableSet;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.terasology.gestalt.module.ModuleEnvironment;
 import org.terasology.gestalt.naming.Name;
 
 import java.util.Collections;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 /**
  * @author Immortius

gestalt-asset-core/src/test/java/org/terasology/gestalt/assets/module/autoreload/ModuleEnvironmentWatcherTest.java

@@ -17,7 +17,7 @@
 package org.terasology.gestalt.assets.module.autoreload;
 
 import com.google.common.collect.SetMultimap;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.terasology.gestalt.assets.AssetType;
@@ -41,10 +41,12 @@
 import java.io.Writer;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.Collections;
 import java.util.Optional;
 
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
 
 public class ModuleEnvironmentWatcherTest {
 
@@ -95,21 +97,45 @@ public Optional<ResourceUrn> deltaFileDeleted(FileReference file, Name module, N
             }
         };
         AssetType<Text, TextData> assetType = new AssetType<>(Text.class, new TextFactory());
+        ResourceUrn urn = new ResourceUrn(module.getId(), new Name("test.txt"));
         watcher.register("text", subscriber, assetType);
         watcher.checkForChanges();
         Files.createDirectories(tempDirectory.resolve("assets").resolve("text"));
         watcher.checkForChanges();
         Files.createFile(tempDirectory.resolve("assets").resolve("text").resolve("test.txt"));
-        SetMultimap<AssetType<?, ?>, ResourceUrn> changed = watcher.checkForChanges();
-        assertTrue(changed.containsEntry(assetType, new ResourceUrn(module.getId(), new Name("test.txt"))));
+        awaitChange(watcher, assetType, urn);
         try (Writer writer = Files.newBufferedWriter(tempDirectory.resolve("assets").resolve("text").resolve("test.txt"))) {
             writer.write("This is my text");
         }
-        changed = watcher.checkForChanges();
-        assertTrue(changed.containsEntry(assetType, new ResourceUrn(module.getId(), new Name("test.txt"))));
+        awaitChange(watcher, assetType, urn);
         FilesUtil.recursiveDelete(tempDirectory);
         watcher.checkForChanges();
 
     }
 
+    /**
+     * checkForChanges() does a single non-blocking WatchService poll - the OS delivers file
+     * events asynchronously (inotify/FSEvents/etc.), so a change made just before calling it can
+     * still be in flight and not show up in that one poll, especially under CI's slower/virtualized
+     * filesystems. Retries for up to 5s instead of asserting on a single poll's result, so the test
+     * doesn't flake on delivery timing while still failing for real if the change never arrives.
+     */
+    private static void awaitChange(ModuleEnvironmentWatcher watcher, AssetType<?, ?> assetType, ResourceUrn urn) throws IOException {
+        Instant deadline = Instant.now().plus(Duration.ofSeconds(5));
+        SetMultimap<AssetType<?, ?>, ResourceUrn> changed;
+        do {
+            changed = watcher.checkForChanges();
+            if (changed.containsEntry(assetType, urn)) {
+                return;
+            }
+            try {
+                Thread.sleep(20);
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+                throw new IOException("Interrupted while waiting for a file change to be detected", e);
+            }
+        } while (Instant.now().isBefore(deadline));
+        fail("Expected " + urn + " to show up as changed within 5s, last poll's result: " + changed);
+    }
+
 }

gestalt-di/build.gradle.kts

@@ -29,7 +29,9 @@ dependencies {
     implementation(libs.guava)
     api(project(":gestalt-inject"))
 
-    testImplementation(libs.junit)
+    testImplementation(libs.junit.jupiter.api)
+    testRuntimeOnly(libs.junit.jupiter.engine)
+    testRuntimeOnly(libs.junit.platform.launcher)
     testImplementation(libs.logback)
     testImplementation(libs.mockito)
 

gestalt-di/gradle.lockfile

@@ -17,19 +17,26 @@ com.googlecode.gentyref:gentyref:1.2.0=testAnnotationProcessor,testRuntimeClassp
 com.squareup:javapoet:1.13.0=testAnnotationProcessor
 com.toasttab.android:gummy-bears-api-24:0.15.0=signature
 javax.inject:javax.inject:1=compileClasspath,runtimeClasspath,testAnnotationProcessor,testCompileClasspath,testRuntimeClasspath
-junit:junit:4.12=testCompileClasspath,testRuntimeClasspath
 net.bytebuddy:byte-buddy-agent:1.17.7=testCompileClasspath,testRuntimeClasspath
 net.bytebuddy:byte-buddy:1.17.7=testCompileClasspath,testRuntimeClasspath
 net.jcip:jcip-annotations:1.0=testRuntimeClasspath
 net.sf.trove4j:trove4j:3.0.3=testRuntimeClasspath
+org.apiguardian:apiguardian-api:1.1.2=testCompileClasspath
 org.checkerframework:checker-compat-qual:2.5.2=compileClasspath,runtimeClasspath,testAnnotationProcessor,testCompileClasspath,testRuntimeClasspath
 org.codehaus.mojo:animal-sniffer-annotations:1.17=compileClasspath,runtimeClasspath,testAnnotationProcessor,testCompileClasspath,testRuntimeClasspath
 org.codehaus.mojo:animal-sniffer-annotations:1.24=animalsniffer
 org.codehaus.mojo:animal-sniffer:1.24=animalsniffer
-org.hamcrest:hamcrest-core:1.3=testCompileClasspath,testRuntimeClasspath
 org.javassist:javassist:3.27.0-GA=testRuntimeClasspath
+org.jspecify:jspecify:1.0.0=testCompileClasspath
+org.junit.jupiter:junit-jupiter-api:6.1.3=testCompileClasspath,testRuntimeClasspath
+org.junit.jupiter:junit-jupiter-engine:6.1.3=testRuntimeClasspath
+org.junit.platform:junit-platform-commons:6.1.3=testCompileClasspath,testRuntimeClasspath
+org.junit.platform:junit-platform-engine:6.1.3=testRuntimeClasspath
+org.junit.platform:junit-platform-launcher:6.1.3=testRuntimeClasspath
+org.junit:junit-bom:6.1.3=testCompileClasspath,testRuntimeClasspath
 org.mockito:mockito-core:5.23.0=testCompileClasspath,testRuntimeClasspath
 org.objenesis:objenesis:3.3=testRuntimeClasspath
+org.opentest4j:opentest4j:1.3.0=testCompileClasspath,testRuntimeClasspath
 org.ow2.asm:asm:9.7=animalsniffer
 org.slf4j:slf4j-api:1.7.25=compileClasspath,runtimeClasspath,testAnnotationProcessor,testCompileClasspath,testRuntimeClasspath
 empty=annotationProcessor