Create a first Maven 4 test case

org.eclipse.m2e.core.tests/resources/projects/HelloMaven4/README.md

@@ -0,0 +1,74 @@
+# Hello Maven 4 Test Project
+
+## Overview
+This is a demonstration project showcasing Maven 4 features for testing m2e compatibility.
+The project is based on real-world usage patterns from [jline3](https://github.com/jline/jline3).
+
+## Project Structure
+```
+HelloMaven4/
+├── pom.xml (parent)
+├── hello-core/ (library subproject)
+│   └── src/main/java/org/eclipse/m2e/tests/demo/core/
+│       └── GreetingService.java
+└── hello-app/ (application subproject)
+    └── src/main/java/org/eclipse/m2e/tests/demo/app/
+        └── HelloWorldApp.java
+```
+
+## Maven 4 Features Used
+
+This project demonstrates the following Maven 4 features from [What's New in Maven 4](https://maven.apache.org/whatsnewinmaven4.html):
+
+### 1. ✅ New Model Version 4.1.0
+- **Feature**: Maven 4 introduces a new POM model version `4.1.0`
+- **Usage**: All POMs use `<modelVersion>4.1.0</modelVersion>` and `xmlns="http://maven.apache.org/POM/4.1.0"` namespace
+- **Location**: All `pom.xml` files
+- **Status**: Demonstrated
+
+### 2. ✅ Subprojects Instead of Modules
+- **Feature**: Maven 4 uses `<subprojects>` instead of `<modules>` for better semantics
+- **Usage**: Parent POM uses `<subprojects>` to declare child projects
+- **Location**: `pom.xml` (parent)
+- **Status**: Demonstrated
+
+### 3. ✅ Inheritance of GroupId and Version
+- **Feature**: Child projects can omit `<groupId>` and `<version>` when inheriting from parent
+- **Usage**: Child POMs (`hello-core` and `hello-app`) omit these elements
+- **Location**: `hello-core/pom.xml` and `hello-app/pom.xml`
+- **Status**: Demonstrated
+
+### 4. ⏳ Build/Consumer POM Split
+- **Feature**: Maven 4 separates build-time and consumption-time concerns
+- **Usage**: Not explicitly demonstrated in this simple project
+- **Status**: Not applicable for this simple test case
+
+### 5. ⏳ Better Java Version Handling
+- **Feature**: Improved handling of Java versions with `maven.compiler.release`
+- **Usage**: Uses `maven.compiler.release` property set to 11
+- **Location**: Parent POM properties
+- **Status**: Partially demonstrated
+
+## Testing with Maven 4
+
+This project is designed to be built with **Maven 4.0.0-rc-2** or later (Preview release).
+
+To verify Maven 4 compatibility:
+```bash
+# Requires Maven 4.0.0-rc-2 or later
+mvn clean install
+```
+
+## Purpose
+
+This test project serves two main goals:
+
+1. **Demonstrate Incompatibility**: Show that current m2e does NOT support Maven 4 features
+2. **Validation Target**: Provide a test case to verify Maven 4 support as it's implemented
+
+## References
+
+- [Apache Maven 4 Downloads](https://maven.apache.org/download.cgi)
+- [What's New in Maven 4](https://maven.apache.org/whatsnewinmaven4.html)
+- [JLine3 Project](https://github.com/jline/jline3) - Real-world Maven 4 usage example
+- [Maven 4 Announcement](https://lists.apache.org/thread/jnb3snhdm4b564gz8hbctp9rfk8fc67n)

org.eclipse.m2e.core.tests/resources/projects/HelloMaven4/hello-app/pom.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+    Maven 4 Subproject - demonstrates dependency on sibling subproject
+
+    This module also inherits groupId and version from parent
+-->
+<project xmlns="http://maven.apache.org/POM/4.1.0" 
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.1.0 https://maven.apache.org/xsd/maven-4.1.0.xsd">
+
+    <modelVersion>4.1.0</modelVersion>
+
+    <parent>
+        <groupId>org.eclipse.m2e.tests.demo</groupId>
+        <artifactId>hello-maven4-parent</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>hello-app</artifactId>
+
+    <name>Hello Maven 4 App</name>
+    <description>Application module demonstrating Maven 4 features</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.eclipse.m2e.tests.demo</groupId>
+            <artifactId>hello-core</artifactId>
+            <version>1.0.0-SNAPSHOT</version>
+        </dependency>
+    </dependencies>
+</project>

org.eclipse.m2e.core.tests/resources/projects/HelloMaven4/hello-app/src/main/java/org/eclipse/m2e/tests/demo/app/HelloWorldApp.java

@@ -0,0 +1,19 @@
+package org.eclipse.m2e.tests.demo.app;
+
+import org.eclipse.m2e.tests.demo.core.GreetingService;
+
+/**
+ * Simple HelloWorld application demonstrating Maven 4 multi-subproject structure.
+ */
+public class HelloWorldApp {
+
+    public static void main(String[] args) {
+        GreetingService service = new GreetingService();
+
+        String name = args.length > 0 ? args[0] : "Maven 4 World";
+        String greeting = service.greet(name);
+
+        System.out.println(greeting);
+        System.out.println("Built with Maven 4!");
+    }
+}

org.eclipse.m2e.core.tests/resources/projects/HelloMaven4/hello-core/pom.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+    Maven 4 Subproject - demonstrates inheritance of groupId and version
+
+    Note: In Maven 4, child projects can omit groupId and version
+    when they inherit from parent, making the POM cleaner
+-->
+<project xmlns="http://maven.apache.org/POM/4.1.0" 
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.1.0 https://maven.apache.org/xsd/maven-4.1.0.xsd">
+
+    <modelVersion>4.1.0</modelVersion>
+
+    <parent>
+        <groupId>org.eclipse.m2e.tests.demo</groupId>
+        <artifactId>hello-maven4-parent</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>hello-core</artifactId>
+
+    <name>Hello Maven 4 Core</name>
+    <description>Core library module demonstrating Maven 4 features</description>
+</project>

org.eclipse.m2e.core.tests/resources/projects/HelloMaven4/hello-core/src/main/java/org/eclipse/m2e/tests/demo/core/GreetingService.java

@@ -0,0 +1,25 @@
+package org.eclipse.m2e.tests.demo.core;
+
+/**
+ * A simple greeting service to demonstrate Maven 4 project structure.
+ */
+public class GreetingService {
+
+    private final String prefix;
+
+    public GreetingService(String prefix) {
+        this.prefix = prefix;
+    }
+
+    public GreetingService() {
+        this("Hello");
+    }
+
+    public String greet(String name) {
+        return prefix + ", " + name + "!";
+    }
+
+    public String getPrefix() {
+        return prefix;
+    }
+}

org.eclipse.m2e.core.tests/resources/projects/HelloMaven4/pom.xml

@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+    Maven 4 Test Project for m2e
+
+    This project demonstrates Maven 4 features including:
+    - Model version 4.1.0
+    - Subprojects instead of modules
+    - Inheritance of groupId and version from parent
+-->
+<project xmlns="http://maven.apache.org/POM/4.1.0" 
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.1.0 https://maven.apache.org/xsd/maven-4.1.0.xsd">
+
+    <modelVersion>4.1.0</modelVersion>
+
+    <groupId>org.eclipse.m2e.tests.demo</groupId>
+    <artifactId>hello-maven4-parent</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+    <packaging>pom</packaging>
+
+    <name>Hello Maven 4 Parent</name>
+    <description>A simple Maven 4 demo project for testing m2e support</description>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.release>11</maven.compiler.release>
+    </properties>
+
+    <subprojects>
+        <subproject>hello-core</subproject>
+        <subproject>hello-app</subproject>
+    </subprojects>
+
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-compiler-plugin</artifactId>
+                    <version>3.11.0</version>
+                </plugin>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-jar-plugin</artifactId>
+                    <version>3.3.0</version>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+</project>

org.eclipse.m2e.core.tests/src/org/eclipse/m2e/core/Maven4Test.java

@@ -0,0 +1,136 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Red Hat Inc. and others
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *      Red Hat Inc. - initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.m2e.core;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import java.io.File;
+
+import org.eclipse.core.resources.IProject;
+import org.eclipse.core.resources.ResourcesPlugin;
+import org.eclipse.core.runtime.FileLocator;
+import org.eclipse.m2e.tests.common.AbstractMavenProjectTestCase;
+import org.junit.After;
+import org.junit.Test;
+
+/**
+ * Test case for Maven 4 support in m2e.
+ * 
+ * This test demonstrates that m2e currently does NOT support Maven 4 features.
+ * As Maven 4 support is implemented, this test can be enhanced to verify:
+ * - Model version 4.1.0 parsing
+ * - Subprojects support (instead of modules)
+ * - Inheritance of groupId and version
+ * - Build/Consumer POM split
+ * 
+ * Based on real-world usage from https://github.com/jline/jline3
+ * 
+ * @see https://maven.apache.org/whatsnewinmaven4.html
+ */
+public class Maven4Test extends AbstractMavenProjectTestCase {
+
+  @After
+  public void clearWorkspace() throws Exception {
+    for(IProject p : ResourcesPlugin.getWorkspace().getRoot().getProjects()) {
+      p.delete(true, null);
+    }
+  }
+
+  /**
+   * Test Maven 4 project with model version 4.1.0 and subprojects.
+   * 
+   * This test attempts to import a Maven 4 project that uses:
+   * - Model version 4.1.0
+   * - Subprojects instead of modules
+   * - Inheritance of groupId and version from parent
+   * 
+   * Expected behavior:
+   * - With current m2e (Maven 3 only): This test is expected to fail or show errors
+   * - With Maven 4 support: This test should pass and projects should be imported correctly
+   */
+  @Test
+  public void testMaven4BasicProject() throws Exception {
+    // Get the Maven 4 test project
+    File sourceDirectory = new File(
+        FileLocator.toFileURL(getClass().getResource("/resources/projects/HelloMaven4")).toURI());
+
+    assertNotNull("HelloMaven4 project directory should exist", sourceDirectory);
+    assertTrue("HelloMaven4 project directory should be a directory", sourceDirectory.isDirectory());
+
+    File parentPom = new File(sourceDirectory, "pom.xml");
+    assertTrue("Parent pom.xml should exist", parentPom.exists());
+
+    // Attempt to import the Maven 4 project
+    // Note: This will likely fail with current m2e since it doesn't support Maven 4
+    try {
+      IProject project = importProject("resources/projects/HelloMaven4/pom.xml");
+
+      // If we get here, the project was imported (unexpected with current m2e)
+      assertNotNull("Parent project should be imported", project);
+
+      // Check if subprojects are recognized
+      // Note: With Maven 4 support, these should be imported as child projects
+      IProject helloCore = ResourcesPlugin.getWorkspace().getRoot().getProject("hello-core");
+      IProject helloApp = ResourcesPlugin.getWorkspace().getRoot().getProject("hello-app");
+
+      // These assertions will help verify Maven 4 support when implemented
+      // For now, they document what should work with Maven 4
+      assertNotNull("hello-core subproject should be recognized", helloCore);
+      assertNotNull("hello-app subproject should be recognized", helloApp);
+
+    } catch (Exception e) {
+      // Expected with current m2e - Maven 4 is not yet supported
+      // This documents that m2e needs Maven 4 support
+      System.err.println("Expected failure with Maven 3 based m2e: " + e.getMessage());
+
+      // For now, we'll let this exception indicate Maven 4 is not supported
+      // When Maven 4 support is added, this test should pass without exceptions
+      fail("Maven 4 project import failed (expected with current m2e): " + e.getMessage());
+    }
+  }
+
+  /**
+   * Test that Maven 4 model version 4.1.0 is recognized.
+   * 
+   * This is a more basic test that just checks if the model version is parsed correctly.
+   * When Maven 4 support is added, this should pass.
+   */
+  @Test
+  public void testMaven4ModelVersion() throws Exception {
+    File sourceDirectory = new File(
+        FileLocator.toFileURL(getClass().getResource("/resources/projects/HelloMaven4")).toURI());
+    File parentPom = new File(sourceDirectory, "pom.xml");
+
+    assertTrue("Parent pom.xml should exist", parentPom.exists());
+
+    // Try to read the POM
+    // With Maven 4 support, this should recognize the 4.1.0 model version
+    try {
+      // This will likely fail with current Maven 3 based implementation
+      // as it doesn't recognize model version 4.1.0
+      @SuppressWarnings("unused")
+      IProject project = importProject("resources/projects/HelloMaven4/pom.xml");
+
+      // If we get here, Maven 4 model version was recognized
+      // This indicates Maven 4 support is working
+
+    } catch (Exception e) {
+      // Expected with current m2e
+      System.err.println("Maven 4 model version not supported yet: " + e.getMessage());
+      fail("Maven 4 model version 4.1.0 is not supported (expected with current m2e): " + e.getMessage());
+    }
+  }
+}