[MNG-7891] IT for configuring extensions (#296)

Co-authored-by: Christoph Läubrich <christoph@laeubi-soft.de>
diff --git a/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng7891ConfigurationForExtensionsTest.java b/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng7891ConfigurationForExtensionsTest.java
new file mode 100644
index 0000000..a390cec
--- /dev/null
+++ b/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng7891ConfigurationForExtensionsTest.java
@@ -0,0 +1,81 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.it;
+
+import java.io.File;
+import java.util.List;
+
+import org.apache.maven.shared.verifier.Verifier;
+import org.apache.maven.shared.verifier.util.ResourceExtractor;
+import org.junit.jupiter.api.Test;
+
+class MavenITmng7891ConfigurationForExtensionsTest extends AbstractMavenIntegrationTestCase {
+
+    protected MavenITmng7891ConfigurationForExtensionsTest() {
+        super("(4.0.0-alpha-7,)");
+    }
+
+    @Test
+    void testConfigurationForCoreExtension() throws Exception {
+        File testDir = ResourceExtractor.simpleExtractResources(getClass(), "/mng-7891-extension-configuration");
+
+        Verifier verifier = newVerifier(new File(testDir, "extension").getAbsolutePath());
+        verifier.addCliArgument("install");
+        verifier.execute();
+        verifier.verifyErrorFreeLog();
+
+        verifier = newVerifier(new File(testDir, "core-extension").getAbsolutePath());
+        verifier.addCliArgument("install");
+        verifier.addCliArgument("-DuserValue=the-value");
+        verifier.execute();
+        verifier.verifyErrorFreeLog();
+
+        List<String> logFile = verifier.loadFile(verifier.getBasedir(), verifier.getLogFileName(), false);
+        String projects = logFile.stream()
+                .filter(s -> s.contains("All projects are read now"))
+                .findFirst()
+                .orElse(null);
+        assertNotNull(projects);
+        assertFalse(projects.contains("$"));
+    }
+
+    @Test
+    void testConfigurationForBuildExtension() throws Exception {
+        File testDir = ResourceExtractor.simpleExtractResources(getClass(), "/mng-7891-extension-configuration");
+
+        Verifier verifier = newVerifier(new File(testDir, "extension").getAbsolutePath());
+        verifier.addCliArgument("install");
+        verifier.execute();
+        verifier.verifyErrorFreeLog();
+
+        verifier = newVerifier(new File(testDir, "build-extension").getAbsolutePath());
+        verifier.addCliArgument("install");
+        verifier.addCliArgument("-DuserValue=the-value");
+        verifier.execute();
+        verifier.verifyErrorFreeLog();
+
+        List<String> logFile = verifier.loadFile(verifier.getBasedir(), verifier.getLogFileName(), false);
+        String projects = logFile.stream()
+                .filter(s -> s.contains("All projects are read now"))
+                .findFirst()
+                .orElse(null);
+        assertNotNull(projects);
+        assertFalse(projects.contains("$"));
+    }
+}
diff --git a/core-it-suite/src/test/java/org/apache/maven/it/TestSuiteOrdering.java b/core-it-suite/src/test/java/org/apache/maven/it/TestSuiteOrdering.java
index 2b8c5e9..a039462 100644
--- a/core-it-suite/src/test/java/org/apache/maven/it/TestSuiteOrdering.java
+++ b/core-it-suite/src/test/java/org/apache/maven/it/TestSuiteOrdering.java
@@ -120,6 +120,7 @@
          * the tests are to finishing. Newer tests are also more likely to fail, so this is
          * a fail fast technique as well.
          */
+        suite.addTestSuite(MavenITmng7891ConfigurationForExtensionsTest.class);
         suite.addTestSuite(MavenITmng6401ProxyPortInterpolationTest.class);
         suite.addTestSuite(MavenITmng7228LeakyModelTest.class);
         suite.addTestSuite(MavenITmng7819FileLockingWithSnapshotsTest.class);
diff --git a/core-it-suite/src/test/resources/mng-7891-extension-configuration/build-extension/pom.xml b/core-it-suite/src/test/resources/mng-7891-extension-configuration/build-extension/pom.xml
new file mode 100644
index 0000000..951402a
--- /dev/null
+++ b/core-it-suite/src/test/resources/mng-7891-extension-configuration/build-extension/pom.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.1.0" root="true">
+  <groupId>org.apache.maven.its.mng7891</groupId>
+  <artifactId>build-extension</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+  <build>
+    <extensions>
+      <extension>
+        <groupId>org.apache.maven.its.mng7891</groupId>
+        <artifactId>extension</artifactId>
+        <version>1.0-SNAPSHOT</version>
+        <configuration>
+          <messages>
+            <sessionStart>The session has just started at ${maven.build.timestamp}</sessionStart>
+            <projectsRead>All projects are read now! The build will start and the user has passed -DuserValue=${userValue} on the commandline</projectsRead>
+          </messages>
+        </configuration>
+      </extension>
+    </extensions>
+  </build>
+</project>
diff --git a/core-it-suite/src/test/resources/mng-7891-extension-configuration/core-extension/.mvn/extensions.xml b/core-it-suite/src/test/resources/mng-7891-extension-configuration/core-extension/.mvn/extensions.xml
new file mode 100644
index 0000000..b11a717
--- /dev/null
+++ b/core-it-suite/src/test/resources/mng-7891-extension-configuration/core-extension/.mvn/extensions.xml
@@ -0,0 +1,13 @@
+<extensions>
+	<extension>
+		<groupId>org.apache.maven.its.mng7891</groupId>
+		<artifactId>extension</artifactId>
+		<version>1.0-SNAPSHOT</version>
+		<configuration>
+			<messages>
+				<sessionStart>The session has just started at ${maven.build.timestamp}</sessionStart>
+				<projectsRead>All projects are read now! The build will start and the user has passed -DuserValue=${userValue} on the commandline</projectsRead>
+			</messages>
+		</configuration>
+	</extension>
+</extensions>
diff --git a/core-it-suite/src/test/resources/mng-7891-extension-configuration/core-extension/pom.xml b/core-it-suite/src/test/resources/mng-7891-extension-configuration/core-extension/pom.xml
new file mode 100644
index 0000000..248798e
--- /dev/null
+++ b/core-it-suite/src/test/resources/mng-7891-extension-configuration/core-extension/pom.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.1.0" root="true">
+  <groupId>org.apache.maven.its.mng7891</groupId>
+  <artifactId>core-extension</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+</project>
diff --git a/core-it-suite/src/test/resources/mng-7891-extension-configuration/extension/pom.xml b/core-it-suite/src/test/resources/mng-7891-extension-configuration/extension/pom.xml
new file mode 100644
index 0000000..d145a98
--- /dev/null
+++ b/core-it-suite/src/test/resources/mng-7891-extension-configuration/extension/pom.xml
@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.1.0" root="true">
+  <groupId>org.apache.maven.its.mng7891</groupId>
+  <artifactId>extension</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <properties>
+    <javaVersion>8</javaVersion>
+    <maven.compiler.source>${javaVersion}</maven.compiler.source>
+    <maven.compiler.target>${javaVersion}</maven.compiler.target>
+    <maven.version>3.8.6</maven.version>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.apache.maven</groupId>
+      <artifactId>maven-core</artifactId>
+      <version>${maven.version}</version>
+      <scope>provided</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.eclipse.sisu</groupId>
+        <artifactId>sisu-maven-plugin</artifactId>
+        <version>0.3.5</version>
+        <executions>
+          <execution>
+            <id>index-project</id>
+            <goals>
+              <goal>main-index</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>
diff --git a/core-it-suite/src/test/resources/mng-7891-extension-configuration/extension/src/main/java/org/apache/maven/its/mng7891/MyLifecycleParticipant.java b/core-it-suite/src/test/resources/mng-7891-extension-configuration/extension/src/main/java/org/apache/maven/its/mng7891/MyLifecycleParticipant.java
new file mode 100644
index 0000000..21f5f67
--- /dev/null
+++ b/core-it-suite/src/test/resources/mng-7891-extension-configuration/extension/src/main/java/org/apache/maven/its/mng7891/MyLifecycleParticipant.java
@@ -0,0 +1,51 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.its.mng7891;
+
+import javax.inject.Inject;
+import javax.inject.Named;
+import javax.inject.Singleton;
+
+import org.apache.maven.AbstractMavenLifecycleParticipant;
+import org.apache.maven.MavenExecutionException;
+import org.apache.maven.execution.MavenSession;
+import org.codehaus.plexus.configuration.PlexusConfiguration;
+import org.codehaus.plexus.logging.Logger;
+
+@Named
+@Singleton
+public class MyLifecycleParticipant extends AbstractMavenLifecycleParticipant {
+
+    private PlexusConfiguration configuration;
+    private Logger logger;
+
+    @Inject
+    public MyLifecycleParticipant(
+            @Named("org.apache.maven.its.mng7891:extension") PlexusConfiguration configuration, Logger logger) {
+        this.configuration = configuration;
+        this.logger = logger;
+    }
+
+    @Override
+    public void afterProjectsRead(MavenSession session) throws MavenExecutionException {
+        PlexusConfiguration messages = configuration.getChild("messages");
+        PlexusConfiguration sessionStart = messages.getChild("projectsRead");
+        logger.info(sessionStart.getValue("No session projects read message configured"));
+    }
+}