[MNG-1701] Validate that a plugin is not configured twice in the pom

git-svn-id: https://svn.apache.org/repos/asf/maven/maven-3/trunk@928426 13f79535-47bb-0310-9956-ffa450edef68

maven-model-builder/src/main/java/org/apache/maven/model/validation/DefaultModelValidator.java

@@ -34,6 +34,7 @@ import org.apache.maven.model.DistributionManagement;
 import org.apache.maven.model.Model;
 import org.apache.maven.model.Parent;
 import org.apache.maven.model.Plugin;
+import org.apache.maven.model.PluginManagement;
 import org.apache.maven.model.Profile;
 import org.apache.maven.model.ReportPlugin;
 import org.apache.maven.model.Reporting;
@@ -95,6 +96,18 @@ public class DefaultModelValidator
 
             validateRepositories( problems, model.getPluginRepositories(), "pluginRepositories.pluginRepository", request );
 
+            Build build = model.getBuild();
+            if ( build != null )
+            {
+                validateRawPlugins( problems, build.getPlugins(), false, request );
+
+                PluginManagement mngt = build.getPluginManagement();
+                if ( mngt != null )
+                {
+                    validateRawPlugins( problems, mngt.getPlugins(), true, request );
+                }
+            }
+
             Set<String> profileIds = new HashSet<String>();
 
             for ( Profile profile : model.getProfiles() )
@@ -124,6 +137,33 @@ public class DefaultModelValidator
         }
     }
 
+    private void validateRawPlugins( ModelProblemCollector problems, List<Plugin> plugins, boolean managed,
+                                     ModelBuildingRequest request )
+    {
+        Severity errOn31 = getSeverity( request, ModelBuildingRequest.VALIDATION_LEVEL_MAVEN_3_1 );
+
+        String prefix = ( managed ? "build.pluginManagement." : "build." ) + "plugins.plugin.";
+
+        Map<String, Plugin> index = new HashMap<String, Plugin>();
+
+        for ( Plugin plugin : plugins )
+        {
+            String key = plugin.getKey();
+
+            Plugin existing = index.get( key );
+
+            if ( existing != null )
+            {
+                addViolation( problems, errOn31, prefix + "(groupId:artifactId)", null,
+                              "must be unique but found duplicate declaration of plugin " + key );
+            }
+            else
+            {
+                index.put( key, plugin );
+            }
+        }
+    }
+
     public void validateEffectiveModel( Model model, ModelBuildingRequest request, ModelProblemCollector problems )
     {
         validateStringNotEmpty( "modelVersion", problems, Severity.ERROR, model.getModelVersion() );

maven-model-builder/src/test/java/org/apache/maven/model/validation/DefaultModelValidatorTest.java

@@ -439,4 +439,15 @@ public class DefaultModelValidatorTest
         assertTrue( result.getWarnings().get( 0 ).contains( "'modules.module' has been specified without a path" ) );
     }
 
+    public void testDuplicatePlugin()
+        throws Exception
+    {
+        SimpleProblemCollector result = validateRaw( "duplicate-plugin.xml" );
+
+        assertViolations( result, 0, 0, 2 );
+
+        assertTrue( result.getWarnings().get( 0 ).contains( "duplicate declaration of plugin test:duplicate" ) );
+        assertTrue( result.getWarnings().get( 1 ).contains( "duplicate declaration of plugin test:managed-duplicate" ) );
+    }
+
 }

maven-model-builder/src/test/resources/poms/validation/duplicate-plugin.xml

@@ -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.
+-->
+
+<project>
+  <modelVersion>4.0.0</modelVersion>
+  <artifactId>aid</artifactId>
+  <groupId>gid</groupId>
+  <version>0.1</version>
+  <packaging>pom</packaging>
+
+  <build>
+    <pluginManagement>
+      <plugins>
+        <plugin>
+          <groupId>test</groupId>
+          <artifactId>managed-duplicate</artifactId>
+        </plugin>
+        <plugin>
+          <groupId>test</groupId>
+          <artifactId>managed-duplicate</artifactId>
+        </plugin>
+      </plugins>
+    </pluginManagement>
+    <plugins>
+      <plugin>
+        <groupId>test</groupId>
+        <artifactId>duplicate</artifactId>
+      </plugin>
+      <plugin>
+        <groupId>test</groupId>
+        <artifactId>duplicate</artifactId>
+      </plugin>
+    </plugins>
+  </build>
+</project>