Added a bit of test

src/main/java/net/neoforged/moddevgradle/tasks/JarJar.java

@@ -12,6 +12,7 @@
 import org.gradle.api.file.FileSystemOperations;
 import org.gradle.api.model.ObjectFactory;
 import org.gradle.api.tasks.InputFiles;
+import org.gradle.api.tasks.Internal;
 import org.gradle.api.tasks.Nested;
 import org.gradle.api.tasks.OutputDirectory;
 import org.gradle.api.tasks.SkipWhenEmpty;
@@ -56,27 +57,36 @@ public abstract class JarJar extends DefaultTask {
  @OutputDirectory
  public abstract DirectoryProperty getOutputDirectory();
 
+ @Internal
+ public abstract DirectoryProperty getBuildDirectory();
+
  private final FileSystemOperations fileSystemOperations;
 
  @Inject
  public JarJar(FileSystemOperations fileSystemOperations) {
  this.fileSystemOperations = fileSystemOperations;
  this.getOutputDirectory().convention(getProject().getLayout().getBuildDirectory().dir("generated/" + getName()));
+ this.getBuildDirectory().convention(getProject().getLayout().getBuildDirectory());
  }
 
  @TaskAction
  protected void run() {
  List<ResolvedJarJarArtifact> includedJars = new ArrayList<>(getJarJarArtifacts().getResolvedArtifacts().get());
  fileSystemOperations.delete(spec -> spec.delete(getOutputDirectory()));
 
+ var buildDir = getBuildDirectory().getAsFile().get().toPath();
+
  var artifactFiles = new ArrayList<>(includedJars.stream().map(ResolvedJarJarArtifact::getFile).toList());
  // Now we have to handle pure file collection dependencies that do not have artifact ids
  for (var file : getInputFiles()) {
  if (!artifactFiles.contains(file)) {
+ // This is only intended for libraries built by this project, so this is a shoddy check
+ if (!file.toPath().startsWith(buildDir)) {
+ throw new GradleException("Cannot embed file dependencies in the jar if they aren't in this projects build directory.");
+ }
+
  // Create a hashcode to use as a version
  var hashCode = hashFile(file);
-
- // We only support file dependencies that are likely built by this project
  includedJars.add(new ResolvedJarJarArtifact(
  file,
  file.getName(),

testproject/jijtest/build.gradle

@@ -2,10 +2,26 @@ plugins {
  id 'net.neoforged.moddev'
 }
 
+sourceSets {
+ service
+}
+
+def serviceJar = tasks.register("serviceJar", Jar) {
+ from(sourceSets.service.output)
+ archiveClassifier = "service"
+ manifest {
+ attributes(
+ 'FMLModType': "LIBRARY"
+ )
+ }
+}
+
 dependencies {
+ implementation files(sourceSets.service.output)
  testImplementation 'org.junit.jupiter:junit-jupiter:5.10.2'
  testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
  jarJar(project(":coremod"))
+ jarJar(files(serviceJar))
 
  jarJar("org.commonmark:commonmark") {
  version {
@@ -35,6 +51,9 @@ neoForge {
  coremod {
  dependency project(":coremod")
  }
+ service {
+ sourceSet sourceSets.service
+ }
  }
 
  unitTest {

testproject/jijtest/src/service/java/jijtestservice/Service.java

@@ -0,0 +1,5 @@
+package jijtestservice;
+
+public class Service {
+
+}

testproject/jijtest/src/service/resources/META-INF/MANIFEST.MF

@@ -0,0 +1,3 @@
+Manifest-Version: 1.0
+Note: Dummy Manifest file only for in-dev runtime
+FMLModType: LIBRARY

testproject/jijtest/src/test/java/jijtest/CoreModTest.java

@@ -12,5 +12,10 @@ public class CoreModTest {
  void testPresenceOfCoreMod() throws Exception {
  var field = assertDoesNotThrow(() -> ItemStack.class.getField("CORE_MOD_MARKER"));
  assertTrue(field.getBoolean(null));
+
+ var obj = new jijtestservice.Service();
+ // ensures it is *not* a transforming classloader, meaning it was loaded in our parent layer
+ assertEquals("cpw.mods.cl.ModuleClassLoader", obj.getClass().getClassLoader().getClass().getName());
+ assertEquals("cpw.mods.modlauncher.TransformingClassLoader", getClass().getClassLoader().getClass().getName());
  }
 }