Add unittests for elements of Model which are neither inherited nor

injected.
Ignoring artifactId and modelVersion, these are required elements.

maven-model-builder/src/test/java/org/apache/maven/model/merge/MavenModelMergerTest.java

@@ -0,0 +1,71 @@
+package org.apache.maven.model.merge;
+
+
+/*
+ * 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.
+ */
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+import java.util.Collections;
+
+import org.apache.maven.model.Model;
+import org.apache.maven.model.Prerequisites;
+import org.apache.maven.model.Profile;
+import org.junit.Test;
+
+public class MavenModelMergerTest
+{
+    private MavenModelMerger modelMerger = new MavenModelMerger();
+
+    // Prerequisites are neither inherited nor injected
+    @Test
+    public void testMergeModel_Prerequisites()
+    {
+        Model parent = new Model();
+        parent.setPrerequisites( new Prerequisites() );
+        Model model = new Model();
+        modelMerger.mergeModel_Prerequisites( model, parent, true, null );
+        assertNull( model.getPrerequisites() );
+        
+        Prerequisites modelPrerequisites = new Prerequisites();
+        modelPrerequisites.setMaven( "3.0" );
+        model.setPrerequisites( modelPrerequisites );
+        modelMerger.mergeModel_Prerequisites( model, parent, true, null );
+        assertEquals( modelPrerequisites, model.getPrerequisites() );
+    }
+
+    // Profiles are neither inherited nor injected
+    @Test
+    public void testMergeModel_Profiles()
+    {
+        Model parent = new Model();
+        parent.setProfiles( Collections.singletonList( new Profile() ) );;
+        Model model = new Model();
+        modelMerger.mergeModel_Profiles( model, parent, true, null );
+        assertEquals( 0, model.getProfiles().size() );
+        
+        Profile modelProfile = new Profile();
+        modelProfile.setId( "MODEL" );
+        model.setProfiles( Collections.singletonList( modelProfile ) );
+        modelMerger.mergeModel_Prerequisites( model, parent, true, null );
+        assertEquals( Collections.singletonList( modelProfile ), model.getProfiles() );
+    }
+
+}