gradlex-org · jjohannes · Nov 2, 2025 · Oct 31, 2025
diff --git a/src/main/java/org/gradlex/javamodule/testing/JavaModuleTestingExtension.java b/src/main/java/org/gradlex/javamodule/testing/JavaModuleTestingExtension.java
@@ -30,8 +30,10 @@
 import org.gradlex.javamodule.testing.internal.bridges.JavaModuleDependenciesBridge;
 import org.gradlex.javamodule.testing.internal.provider.WhiteboxTestCompileArgumentProvider;
 import org.gradlex.javamodule.testing.internal.provider.WhiteboxTestRuntimeArgumentProvider;
+import org.jspecify.annotations.NullMarked;
 
 @SuppressWarnings("UnstableApiUsage")
+@NullMarked
 public abstract class JavaModuleTestingExtension {
     private static final Action<WhiteboxJvmTestSuite> NO_OP_ACTION = c -> {};
 
@@ -251,7 +253,6 @@ private void configureJvmTestSuiteForWhitebox(
                             .orElseGet(() -> {
                                 WhiteboxTestCompileArgumentProvider newProvider =
                                         new WhiteboxTestCompileArgumentProvider(
-                                                sourcesUnderTest.getJava().getSrcDirs(),
                                                 testSources.getJava().getSrcDirs(),
                                                 moduleInfoParser,
                                                 project.getObjects());
@@ -263,6 +264,7 @@ private void configureJvmTestSuiteForWhitebox(
                                         project.getObjects().newInstance(JavaCompileSetModulePathAction.class));
                                 return newProvider;
                             });
+            argumentProvider.setMainSourceFolders(sourcesUnderTest.getJava().getSrcDirs());
             argumentProvider.testRequires(
                     JavaModuleDependenciesBridge.getCompileClasspathModules(project, testSources));
             argumentProvider.testRequires(whiteboxJvmTestSuite.getRequires());
@@ -289,15 +291,15 @@ private void configureJvmTestSuiteForWhitebox(
                             .orElseGet(() -> {
                                 WhiteboxTestRuntimeArgumentProvider newProvider =
                                         new WhiteboxTestRuntimeArgumentProvider(
-                                                sourcesUnderTest.getJava().getSrcDirs(),
                                                 testSources.getJava().getClassesDirectory(),
-                                                sourcesUnderTest.getOutput().getResourcesDir(),
                                                 testSources.getOutput().getResourcesDir(),
                                                 moduleInfoParser,
                                                 project.getObjects());
                                 test.getJvmArgumentProviders().add(newProvider);
                                 return newProvider;
                             });
+            argumentProvider.setMainSourceFolders(sourcesUnderTest.getJava().getSrcDirs());
+            argumentProvider.setResourcesUnderTest(sourcesUnderTest.getOutput().getResourcesDir());
             argumentProvider.testRequires(
                     JavaModuleDependenciesBridge.getRuntimeClasspathModules(project, testSources));
             argumentProvider.testRequires(whiteboxJvmTestSuite.getRequires());

diff --git a/src/main/java/org/gradlex/javamodule/testing/TaskLockService.java b/src/main/java/org/gradlex/javamodule/testing/TaskLockService.java
@@ -3,11 +3,13 @@
 
 import org.gradle.api.services.BuildService;
 import org.gradle.api.services.BuildServiceParameters;
+import org.jspecify.annotations.NullMarked;
 
 /**
  * No-op service that can serve as 'lock' to prevent multiple test tasks from running in parallel:
  * usesService(gradle.sharedServices.registerIfAbsent(TaskLockService.NAME, TaskLockService::class) { maxParallelUsages = 1 })
  */
+@NullMarked
 public abstract class TaskLockService implements BuildService<BuildServiceParameters.None> {
     public static String NAME = "taskLock";
 }
diff --git a/src/main/java/org/gradlex/javamodule/testing/WhiteboxJvmTestSuite.java b/src/main/java/org/gradlex/javamodule/testing/WhiteboxJvmTestSuite.java
@@ -4,7 +4,9 @@
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.Property;
 import org.gradle.api.tasks.SourceSet;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 public interface WhiteboxJvmTestSuite {
 
     /**

diff --git a/src/main/java/org/gradlex/javamodule/testing/internal/ModuleInfoParser.java b/src/main/java/org/gradlex/javamodule/testing/internal/ModuleInfoParser.java
@@ -9,7 +9,10 @@
 import org.gradle.api.file.RegularFile;
 import org.gradle.api.provider.Provider;
 import org.gradle.api.provider.ProviderFactory;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
+@NullMarked
 public class ModuleInfoParser {
 
     private final ProjectLayout layout;
@@ -20,6 +23,7 @@ public ModuleInfoParser(ProjectLayout layout, ProviderFactory providers) {
         this.providers = providers;
     }
 
+    @Nullable
     public String moduleName(Set<File> sourceFolders) {
         for (File folder : sourceFolders) {
             Provider<RegularFile> moduleInfoFile =
@@ -33,6 +37,7 @@ public String moduleName(Set<File> sourceFolders) {
         return null;
     }
 
+    @Nullable
     static String moduleName(String moduleInfoFileContent) {
         boolean inComment = false;
         boolean moduleKeywordFound = false;

diff --git a/src/main/java/org/gradlex/javamodule/testing/internal/ModuleInfoRequiresParser.java b/src/main/java/org/gradlex/javamodule/testing/internal/ModuleInfoRequiresParser.java
@@ -4,7 +4,9 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 public class ModuleInfoRequiresParser {
     private static final String RUNTIME_KEYWORD = "/*runtime*/";
 

diff --git a/...in/java/org/gradlex/javamodule/testing/internal/bridges/JavaModuleDependenciesBridge.java b/...in/java/org/gradlex/javamodule/testing/internal/bridges/JavaModuleDependenciesBridge.java
@@ -7,9 +7,13 @@
 import org.gradle.api.Project;
 import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.SourceSet;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
+@NullMarked
 public class JavaModuleDependenciesBridge {
 
+    @Nullable
     public static Provider<?> create(Project project, String moduleName, SourceSet sourceSetWithModuleInfo) {
         Object javaModuleDependencies = project.getExtensions().findByName("javaModuleDependencies");
         if (javaModuleDependencies == null) {

diff --git a/...org/gradlex/javamodule/testing/internal/provider/WhiteboxTestCompileArgumentProvider.java b/...org/gradlex/javamodule/testing/internal/provider/WhiteboxTestCompileArgumentProvider.java
@@ -11,25 +11,29 @@
 import org.gradle.api.provider.Provider;
 import org.gradle.process.CommandLineArgumentProvider;
 import org.gradlex.javamodule.testing.internal.ModuleInfoParser;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 public class WhiteboxTestCompileArgumentProvider implements CommandLineArgumentProvider {
-    private final Set<File> mainSourceFolders;
     private final Set<File> testSourceFolders;
     private final ModuleInfoParser moduleInfoParser;
 
+    @SuppressWarnings("NotNullFieldNotInitialized")
+    private Set<File> mainSourceFolders;
+
     private final ListProperty<String> allTestRequires;
 
     public WhiteboxTestCompileArgumentProvider(
-            Set<File> mainSourceFolders,
-            Set<File> testSourceFolders,
-            ModuleInfoParser moduleInfoParser,
-            ObjectFactory objects) {
-        this.mainSourceFolders = mainSourceFolders;
+            Set<File> testSourceFolders, ModuleInfoParser moduleInfoParser, ObjectFactory objects) {
         this.testSourceFolders = testSourceFolders;
         this.moduleInfoParser = moduleInfoParser;
         this.allTestRequires = objects.listProperty(String.class);
     }
 
+    public void setMainSourceFolders(Set<File> mainSourceFolders) {
+        this.mainSourceFolders = mainSourceFolders;
+    }
+
     public void testRequires(Provider<List<String>> testRequires) {
         allTestRequires.addAll(testRequires);
     }

diff --git a/...org/gradlex/javamodule/testing/internal/provider/WhiteboxTestRuntimeArgumentProvider.java b/...org/gradlex/javamodule/testing/internal/provider/WhiteboxTestRuntimeArgumentProvider.java
@@ -12,36 +12,45 @@
 import org.gradle.api.provider.Provider;
 import org.gradle.process.CommandLineArgumentProvider;
 import org.gradlex.javamodule.testing.internal.ModuleInfoParser;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 public class WhiteboxTestRuntimeArgumentProvider implements CommandLineArgumentProvider {
-    private final Set<File> mainSourceFolders;
     private final Provider<Directory> testClassesFolders;
-    private final File resourcesUnderTest;
     private final File testResources;
     private final ModuleInfoParser moduleInfoParser;
 
+    @SuppressWarnings("NotNullFieldNotInitialized")
+    private Set<File> mainSourceFolders;
+
+    @SuppressWarnings("NotNullFieldNotInitialized")
+    private File resourcesUnderTest;
+
     private final ListProperty<String> allTestRequires;
     private final ListProperty<String> allTestOpensTo;
     private final ListProperty<String> allTestExportsTo;
 
     public WhiteboxTestRuntimeArgumentProvider(
-            Set<File> mainSourceFolders,
             Provider<Directory> testClassesFolders,
-            File resourcesUnderTest,
             File testResources,
             ModuleInfoParser moduleInfoParser,
             ObjectFactory objects) {
-
-        this.mainSourceFolders = mainSourceFolders;
         this.testClassesFolders = testClassesFolders;
-        this.resourcesUnderTest = resourcesUnderTest;
         this.testResources = testResources;
         this.moduleInfoParser = moduleInfoParser;
         this.allTestRequires = objects.listProperty(String.class);
         this.allTestOpensTo = objects.listProperty(String.class);
         this.allTestExportsTo = objects.listProperty(String.class);
     }
 
+    public void setMainSourceFolders(Set<File> mainSourceFolders) {
+        this.mainSourceFolders = mainSourceFolders;
+    }
+
+    public void setResourcesUnderTest(File resourcesUnderTest) {
+        this.resourcesUnderTest = resourcesUnderTest;
+    }
+
     public void testRequires(Provider<List<String>> testRequires) {
         allTestRequires.addAll(testRequires);
     }

diff --git a/src/test/java/org/gradlex/javamodule/testing/test/CustomizationTest.java b/src/test/java/org/gradlex/javamodule/testing/test/CustomizationTest.java
@@ -36,6 +36,36 @@ void can_customize_whitebox_test_suites_in_multiple_steps() {
         assertThat(testResult.getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
     }
 
+    @Test
+    void can_change_sourcesUnderTest_of_whitebox_test_suite() {
+        build.useTestFixturesPlugin();
+        build.file("app/src/testFixtures/java/module-info.java")
+                .writeText("""
+            module org.example.fixtures {
+            }
+            """);
+        build.file("app/src/testFixtures/java/org/example/app/Main.java")
+                .writeText("""
+            package org.example.app;
+            public class Main {}
+            """);
+        build.appBuildFile.appendText(
+                """
+            javaModuleTesting.whitebox(testing.suites["test"]) {
+                sourcesUnderTest.set(sourceSets.testFixtures);
+                requires.add("org.junit.jupiter.api")
+            }
+            """);
+
+        var result = build.runTests();
+        var testResult = result.task(":app:test");
+
+        assertThat(result.getOutput()).contains("Main Module: org.example.fixtures");
+        assertThat(result.getOutput()).contains("Test Module: org.example.fixtures");
+        assertThat(testResult).isNotNull();
+        assertThat(testResult.getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+    }
+
     @Test
     void can_define_whitebox_test_suite_requires_in_moduleinfo_file() {
         build.appModuleInfoFile.writeText("""

diff --git a/src/test/java/org/gradlex/javamodule/testing/test/fixture/GradleBuild.java b/src/test/java/org/gradlex/javamodule/testing/test/fixture/GradleBuild.java
@@ -74,7 +74,7 @@ public GradleBuild(Path dir) {
                 testLogging.showStandardStreams = true
             }
             tasks.withType<JavaCompile>().configureEach { options.release.set(11) }
-        """
+            """
                         .formatted(launcherDependency));
         file("app/src/main/java/org/example/app/Main.java")
                 .writeText(
@@ -151,15 +151,11 @@ public BuildResult fail() {
     }
 
     public GradleRunner runner(String... args) {
-        return runner(true, args);
-    }
-
-    public GradleRunner runner(boolean projectIsolation, String... args) {
         boolean debugMode = ManagementFactory.getRuntimeMXBean()
                 .getInputArguments()
                 .toString()
                 .contains("-agentlib:jdwp");
-        List<String> latestFeaturesArgs = GRADLE_VERSION_UNDER_TEST != null || !projectIsolation
+        List<String> latestFeaturesArgs = GRADLE_VERSION_UNDER_TEST != null || debugMode
                 ? List.of()
                 : List.of(
                         "--configuration-cache",