[MNG-6118] Make Maven aware of all projects in a multi module project when using -f or when changing directory to a submodule.

This closes #373

maven-core/src/main/java/org/apache/maven/graph/DefaultGraphBuilder.java

@@ -21,7 +21,6 @@ package org.apache.maven.graph;
 
 import java.io.File;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -36,7 +35,6 @@ import javax.inject.Inject;
 import javax.inject.Named;
 import javax.inject.Singleton;
 
-import org.apache.maven.DefaultMaven;
 import org.apache.maven.MavenExecutionException;
 import org.apache.maven.ProjectCycleException;
 import org.apache.maven.artifact.ArtifactUtils;
@@ -46,20 +44,17 @@ import org.apache.maven.execution.MavenSession;
 import org.apache.maven.execution.ProjectDependencyGraph;
 import org.apache.maven.model.Plugin;
 import org.apache.maven.model.building.DefaultModelProblem;
-import org.apache.maven.model.building.ModelProblem;
-import org.apache.maven.model.building.ModelProblemUtils;
-import org.apache.maven.model.building.ModelSource;
 import org.apache.maven.model.building.Result;
-import org.apache.maven.model.building.UrlModelSource;
 import org.apache.maven.project.DuplicateProjectException;
 import org.apache.maven.project.MavenProject;
-import org.apache.maven.project.ProjectBuilder;
 import org.apache.maven.project.ProjectBuildingException;
-import org.apache.maven.project.ProjectBuildingRequest;
-import org.apache.maven.project.ProjectBuildingResult;
-import org.codehaus.plexus.logging.Logger;
+import org.apache.maven.project.collector.MultiModuleCollectionStrategy;
+import org.apache.maven.project.collector.PomlessCollectionStrategy;
+import org.apache.maven.project.collector.RequestPomCollectionStrategy;
 import org.codehaus.plexus.util.StringUtils;
 import org.codehaus.plexus.util.dag.CycleDetectedException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import static java.util.Comparator.comparing;
 
@@ -71,15 +66,24 @@ import static java.util.Comparator.comparing;
 public class DefaultGraphBuilder
     implements GraphBuilder
 {
+    private static final Logger LOGGER = LoggerFactory.getLogger( DefaultGraphBuilder.class );
+
+    private final BuildResumptionDataRepository buildResumptionDataRepository;
+    private final PomlessCollectionStrategy pomlessCollectionStrategy;
+    private final MultiModuleCollectionStrategy multiModuleCollectionStrategy;
+    private final RequestPomCollectionStrategy requestPomCollectionStrategy;
 
     @Inject
-    private Logger logger;
-
-    @Inject
-    protected ProjectBuilder projectBuilder;
-
-    @Inject
-    private BuildResumptionDataRepository buildResumptionDataRepository;
+    public DefaultGraphBuilder( BuildResumptionDataRepository buildResumptionDataRepository,
+                                PomlessCollectionStrategy pomlessCollectionStrategy,
+                                MultiModuleCollectionStrategy multiModuleCollectionStrategy,
+                                RequestPomCollectionStrategy requestPomCollectionStrategy )
+    {
+        this.buildResumptionDataRepository = buildResumptionDataRepository;
+        this.pomlessCollectionStrategy = pomlessCollectionStrategy;
+        this.multiModuleCollectionStrategy = multiModuleCollectionStrategy;
+        this.requestPomCollectionStrategy = requestPomCollectionStrategy;
+    }
 
     @Override
     public Result<ProjectDependencyGraph> build( MavenSession session )
@@ -91,7 +95,7 @@ public class DefaultGraphBuilder
             if ( result == null )
             {
                 final List<MavenProject> projects = getProjectsForMavenReactor( session );
-                validateProjects( projects );
+                validateProjects( projects, session.getRequest() );
                 enrichRequestFromResumptionData( projects, session.getRequest() );
                 result = reactorDependencyGraph( session, projects );
             }
@@ -133,6 +137,7 @@ public class DefaultGraphBuilder
     {
         ProjectDependencyGraph projectDependencyGraph = new DefaultProjectDependencyGraph( projects );
         List<MavenProject> activeProjects = projectDependencyGraph.getSortedProjects();
+        activeProjects = trimProjectsToRequest( activeProjects, projectDependencyGraph, session.getRequest() );
         activeProjects = trimSelectedProjects( activeProjects, projectDependencyGraph, session.getRequest() );
         activeProjects = trimResumedProjects( activeProjects, projectDependencyGraph, session.getRequest() );
         activeProjects = trimExcludedProjects( activeProjects, session.getRequest() );
@@ -145,6 +150,26 @@ public class DefaultGraphBuilder
         return Result.success( projectDependencyGraph );
     }
 
+    private List<MavenProject> trimProjectsToRequest( List<MavenProject> activeProjects,
+                                                      ProjectDependencyGraph graph,
+                                                      MavenExecutionRequest request )
+            throws MavenExecutionException
+    {
+        List<MavenProject> result = activeProjects;
+
+        if ( request.getPom() != null )
+        {
+            result = getProjectsInRequestScope( request, activeProjects );
+
+            List<MavenProject> sortedProjects = graph.getSortedProjects();
+            result.sort( comparing( sortedProjects::indexOf ) );
+
+            result = includeAlsoMakeTransitively( result, request, graph );
+        }
+
+        return result;
+    }
+
     private List<MavenProject> trimSelectedProjects( List<MavenProject> projects, ProjectDependencyGraph graph,
                                                      MavenExecutionRequest request )
         throws MavenExecutionException
@@ -287,6 +312,28 @@ public class DefaultGraphBuilder
         }
     }
 
+    private List<MavenProject> getProjectsInRequestScope( MavenExecutionRequest request, List<MavenProject> projects )
+            throws MavenExecutionException
+    {
+        if ( request.getPom() == null )
+        {
+            return projects;
+        }
+
+        MavenProject requestPomProject = projects.stream()
+                .filter( project -> request.getPom().equals( project.getFile() ) )
+                .findFirst()
+                .orElseThrow( () -> new MavenExecutionException(
+                        "Could not find a project in reactor matching the request POM", request.getPom() ) );
+
+        List<MavenProject> modules = requestPomProject.getCollectedProjects() != null
+                ? requestPomProject.getCollectedProjects() : Collections.emptyList();
+
+        List<MavenProject> result = new ArrayList<>( modules );
+        result.add( requestPomProject );
+        return result;
+    }
+
     private String formatProjects( List<MavenProject> projects )
     {
         StringBuilder projectNames = new StringBuilder();
@@ -361,76 +408,32 @@ public class DefaultGraphBuilder
         throws ProjectBuildingException
     {
         MavenExecutionRequest request = session.getRequest();
-
         request.getProjectBuildingRequest().setRepositorySession( session.getRepositorySession() );
 
-        List<MavenProject> projects = new ArrayList<>();
-
-        // We have no POM file.
-        //
+        // 1. Collect project for invocation without a POM.
         if ( request.getPom() == null )
         {
-            ModelSource modelSource = new UrlModelSource( DefaultMaven.class.getResource( "project/standalone.xml" ) );
-            MavenProject project = projectBuilder.build( modelSource, request.getProjectBuildingRequest() )
-                .getProject();
-            project.setExecutionRoot( true );
-            projects.add( project );
-            request.setProjectPresent( false );
+            return pomlessCollectionStrategy.collectProjects( request );
+        }
+
+        // 2. Collect projects for all modules in the multi-module project.
+        List<MavenProject> projects = multiModuleCollectionStrategy.collectProjects( request );
+        if ( !projects.isEmpty() )
+        {
             return projects;
         }
 
-        List<File> files = Arrays.asList( request.getPom().getAbsoluteFile() );
-        collectProjects( projects, files, request );
-        return projects;
+        // 3. Collect projects for explicitly requested POM.
+        return requestPomCollectionStrategy.collectProjects( request );
     }
 
-    private void collectProjects( List<MavenProject> projects, List<File> files, MavenExecutionRequest request )
-        throws ProjectBuildingException
-    {
-        ProjectBuildingRequest projectBuildingRequest = request.getProjectBuildingRequest();
-
-        List<ProjectBuildingResult> results = projectBuilder.build( files, request.isRecursive(),
-                                                                    projectBuildingRequest );
-
-        boolean problems = false;
-
-        for ( ProjectBuildingResult result : results )
-        {
-            projects.add( result.getProject() );
-
-            if ( !result.getProblems().isEmpty() && logger.isWarnEnabled() )
-            {
-                logger.warn( "" );
-                logger.warn( "Some problems were encountered while building the effective model for "
-                    + result.getProject().getId() );
-
-                for ( ModelProblem problem : result.getProblems() )
-                {
-                    String loc = ModelProblemUtils.formatLocation( problem, result.getProjectId() );
-                    logger.warn( problem.getMessage() + ( StringUtils.isNotEmpty( loc ) ? " @ " + loc : "" ) );
-                }
-
-                problems = true;
-            }
-        }
-
-        if ( problems )
-        {
-            logger.warn( "" );
-            logger.warn( "It is highly recommended to fix these problems"
-                + " because they threaten the stability of your build." );
-            logger.warn( "" );
-            logger.warn( "For this reason, future Maven versions might no"
-                + " longer support building such malformed projects." );
-            logger.warn( "" );
-        }
-    }
-
-    private void validateProjects( List<MavenProject> projects )
+    private void validateProjects( List<MavenProject> projects, MavenExecutionRequest request )
+            throws MavenExecutionException
     {
         Map<String, MavenProject> projectsMap = new HashMap<>();
 
-        for ( MavenProject p : projects )
+        List<MavenProject> projectsInRequestScope = getProjectsInRequestScope( request, projects );
+        for ( MavenProject p : projectsInRequestScope )
         {
             String projectKey = ArtifactUtils.key( p.getGroupId(), p.getArtifactId(), p.getVersion() );
 
@@ -449,9 +452,8 @@ public class DefaultGraphBuilder
 
                     if ( projectsMap.containsKey( pluginKey ) )
                     {
-                        logger.warn( project.getName() + " uses " + plugin.getKey()
-                            + " as extensions, which is not possible within the same reactor build. "
-                            + "This plugin was pulled from the local repository!" );
+                        LOGGER.warn( "{} uses {} as extensions, which is not possible within the same reactor build. "
+                            + "This plugin was pulled from the local repository!", project.getName(), plugin.getKey() );
                     }
                 }
             }

maven-core/src/main/java/org/apache/maven/project/DefaultModelBuildingListener.java

@@ -106,7 +106,7 @@ public class DefaultModelBuildingListener
             catch ( PluginResolutionException | PluginManagerException | PluginVersionResolutionException e )
             {
                 event.getProblems().add( new ModelProblemCollectorRequest( Severity.ERROR, Version.BASE )
-                        .setMessage( "Unresolveable build extension: " + e.getMessage() )
+                        .setMessage( "Unresolvable build extension: " + e.getMessage() )
                         .setException( e ) );
             }
 

maven-core/src/main/java/org/apache/maven/project/collector/DefaultProjectsCollector.java

@@ -0,0 +1,98 @@
+package org.apache.maven.project.collector;
+
+/*
+ * 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 org.apache.maven.execution.MavenExecutionRequest;
+import org.apache.maven.model.building.ModelProblem;
+import org.apache.maven.model.building.ModelProblemUtils;
+import org.apache.maven.project.MavenProject;
+import org.apache.maven.project.ProjectBuilder;
+import org.apache.maven.project.ProjectBuildingException;
+import org.apache.maven.project.ProjectBuildingRequest;
+import org.apache.maven.project.ProjectBuildingResult;
+import org.codehaus.plexus.util.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.inject.Inject;
+import javax.inject.Named;
+import javax.inject.Singleton;
+import java.io.File;
+import java.util.List;
+
+/**
+ * Utility to collect projects for a given set of pom.xml files.
+ */
+@Named
+@Singleton
+public class DefaultProjectsCollector implements ProjectsCollector
+{
+    private static final Logger LOGGER = LoggerFactory.getLogger( DefaultProjectsCollector.class );
+    private final ProjectBuilder projectBuilder;
+
+    @Inject
+    public DefaultProjectsCollector( ProjectBuilder projectBuilder )
+    {
+        this.projectBuilder = projectBuilder;
+    }
+
+    @Override
+    public void collectProjects( List<MavenProject> projects, List<File> files, MavenExecutionRequest request )
+            throws ProjectBuildingException
+    {
+        ProjectBuildingRequest projectBuildingRequest = request.getProjectBuildingRequest();
+
+        List<ProjectBuildingResult> results = projectBuilder.build( files, request.isRecursive(),
+                projectBuildingRequest );
+
+        boolean problems = false;
+
+        for ( ProjectBuildingResult result : results )
+        {
+            projects.add( result.getProject() );
+
+            if ( !result.getProblems().isEmpty() && LOGGER.isWarnEnabled() )
+            {
+                LOGGER.warn( "" );
+                LOGGER.warn( "Some problems were encountered while building the effective model for {}",
+                        result.getProject().getId() );
+
+                for ( ModelProblem problem : result.getProblems() )
+                {
+                    String loc = ModelProblemUtils.formatLocation( problem, result.getProjectId() );
+                    LOGGER.warn( "{}{}", problem.getMessage(), ( StringUtils.isNotEmpty( loc ) ? " @ " + loc : "" ) );
+                }
+
+                problems = true;
+            }
+        }
+
+        if ( problems )
+        {
+            LOGGER.warn( "" );
+            LOGGER.warn( "It is highly recommended to fix these problems"
+                    + " because they threaten the stability of your build." );
+            LOGGER.warn( "" );
+            LOGGER.warn( "For this reason, future Maven versions might no"
+                    + " longer support building such malformed projects." );
+            LOGGER.warn( "" );
+        }
+    }
+}

maven-core/src/main/java/org/apache/maven/project/collector/MultiModuleCollectionStrategy.java

@@ -0,0 +1,195 @@
+package org.apache.maven.project.collector;
+
+/*
+ * 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 org.apache.maven.execution.MavenExecutionRequest;
+import org.apache.maven.model.Plugin;
+import org.apache.maven.model.building.ModelProblem;
+import org.apache.maven.model.locator.ModelLocator;
+import org.apache.maven.plugin.PluginManagerException;
+import org.apache.maven.plugin.PluginResolutionException;
+import org.apache.maven.project.MavenProject;
+import org.apache.maven.project.ProjectBuildingException;
+import org.apache.maven.project.ProjectBuildingResult;
+import org.eclipse.aether.resolution.ArtifactResolutionException;
+import org.eclipse.aether.transfer.ArtifactNotFoundException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.inject.Inject;
+import javax.inject.Named;
+import javax.inject.Singleton;
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.function.Predicate;
+
+/**
+ * Strategy for collecting Maven projects from the multi-module project root, even when executed in a submodule.
+ */
+@Named( "MultiModuleCollectionStrategy" )
+@Singleton
+public class MultiModuleCollectionStrategy implements ProjectCollectionStrategy
+{
+    private final Logger logger = LoggerFactory.getLogger( getClass() );
+    private final ModelLocator modelLocator;
+    private final ProjectsCollector projectsCollector;
+
+    @Inject
+    public MultiModuleCollectionStrategy( ModelLocator modelLocator, ProjectsCollector projectsCollector )
+    {
+        this.modelLocator = modelLocator;
+        this.projectsCollector = projectsCollector;
+    }
+
+    @Override
+    public List<MavenProject> collectProjects( MavenExecutionRequest request ) throws ProjectBuildingException
+    {
+        File moduleProjectPomFile = getMultiModuleProjectPomFile( request );
+        List<File> files = Collections.singletonList( moduleProjectPomFile.getAbsoluteFile() );
+        try
+        {
+            List<MavenProject> projects = new ArrayList<>();
+            projectsCollector.collectProjects( projects, files, request );
+            boolean isRequestedProjectCollected = isRequestedProjectCollected( request, projects );
+            if ( isRequestedProjectCollected )
+            {
+                return projects;
+            }
+            else
+            {
+                logger.debug( "Multi module project collection failed: {}"
+                        + "Detected a POM file next to a .mvn folder in a parent directory ({}). "
+                        + "Maven assumed that POM file to be the parent of the requested project ({}), but it turned "
+                        + "out that it was not. Another project collection strategy will be executed as result.",
+                        System.lineSeparator(), moduleProjectPomFile.getAbsolutePath(),
+                        request.getPom().getAbsolutePath() );
+                return Collections.emptyList();
+            }
+        }
+        catch ( ProjectBuildingException e )
+        {
+            boolean fallThrough = isModuleOutsideRequestScopeDependingOnPluginModule( request, e );
+
+            if ( fallThrough )
+            {
+                logger.debug( "Multi module project collection failed: {}"
+                        + "Detected that one of the modules of this multi module project uses another module as "
+                        + "plugin extension which still needed to be built. This is not possible within the same "
+                        + "reactor build. Another project collection strategy will be executed as result.",
+                        System.lineSeparator() );
+                return Collections.emptyList();
+            }
+
+            throw e;
+        }
+    }
+
+    private File getMultiModuleProjectPomFile( MavenExecutionRequest request )
+    {
+        if ( request.getPom().getParentFile().equals( request.getMultiModuleProjectDirectory() ) )
+        {
+            return request.getPom();
+        }
+        else
+        {
+            File multiModuleProjectPom = modelLocator.locatePom( request.getMultiModuleProjectDirectory() );
+            if ( !multiModuleProjectPom.exists() )
+            {
+                logger.info( "Maven detected that the requested POM file is part of a multi module project, "
+                        + "but could not find a pom.xml file in the multi module root directory: '"
+                        + request.getMultiModuleProjectDirectory() + "'. " );
+                logger.info( "The reactor is limited to all projects under: " + request.getPom().getParent() );
+                return request.getPom();
+            }
+
+            return multiModuleProjectPom;
+        }
+    }
+
+    /**
+     * multiModuleProjectDirectory in MavenExecutionRequest is not always the parent of the request pom.
+     * We should always check whether the request pom project is collected.
+     * The integration tests for MNG-6223 are examples for this scenario.
+     *
+     * @return true if the collected projects contain the requested project (for example with -f)
+     */
+    private boolean isRequestedProjectCollected( MavenExecutionRequest request, List<MavenProject> projects )
+    {
+        return projects.stream()
+                .map( MavenProject::getFile )
+                .anyMatch( request.getPom()::equals );
+    }
+
+    /**
+     * This method finds out whether collecting projects failed because of the following scenario:
+     * - A multi module project containing a module which is a plugin and another module which depends on it.
+     * - Just the plugin is being built with the -f <pom> flag.
+     * - Because of inter-module dependency collection, all projects in the multi-module project are collected.
+     * - The plugin is not yet installed in a repository.
+     *
+     * Therefore the build fails because the plugin is not found and plugins cannot be built in the same session.
+     *
+     * The integration test for <a href="https://issues.apache.org/jira/browse/MNG-5572">MNG-5572</a> is an
+     *   example of this scenario.
+     *
+     * @return true if the module which fails to collect the inter-module plugin is not part of the build.
+     */
+    private boolean isModuleOutsideRequestScopeDependingOnPluginModule( MavenExecutionRequest request,
+                                                                        ProjectBuildingException exception )
+    {
+        return exception.getResults().stream()
+                .map( ProjectBuildingResult::getProject )
+                .filter( Objects::nonNull )
+                .filter( project -> request.getPom().equals( project.getFile() ) )
+                .findFirst()
+                .map( requestPomProject ->
+                {
+                    List<MavenProject> modules = requestPomProject.getCollectedProjects() != null
+                            ? requestPomProject.getCollectedProjects() : Collections.emptyList();
+                    List<MavenProject> projectsInRequestScope = new ArrayList<>( modules );
+                    projectsInRequestScope.add( requestPomProject );
+
+                    Predicate<ProjectBuildingResult> projectsOutsideOfRequestScope =
+                            pr -> !projectsInRequestScope.contains( pr.getProject() );
+
+                    Predicate<Exception> pluginArtifactNotFoundException =
+                            exc -> exc instanceof PluginManagerException
+                                    && exc.getCause() instanceof PluginResolutionException
+                                    && exc.getCause().getCause() instanceof ArtifactResolutionException
+                                    && exc.getCause().getCause().getCause() instanceof ArtifactNotFoundException;
+
+                    Predicate<Plugin> isPluginPartOfRequestScope = plugin -> projectsInRequestScope.stream()
+                            .anyMatch( project -> project.getGroupId().equals( plugin.getGroupId() )
+                                    && project.getArtifactId().equals( plugin.getArtifactId() )
+                                    && project.getVersion().equals( plugin.getVersion() ) );
+
+                    return exception.getResults().stream()
+                            .filter( projectsOutsideOfRequestScope )
+                            .flatMap( projectBuildingResult -> projectBuildingResult.getProblems().stream() )
+                            .map( ModelProblem::getException )
+                            .filter( pluginArtifactNotFoundException )
+                            .map( exc -> ( ( PluginResolutionException ) exc.getCause() ).getPlugin() )
+                            .anyMatch( isPluginPartOfRequestScope );
+                } ).orElse( false );
+    }
+}

maven-core/src/main/java/org/apache/maven/project/collector/PomlessCollectionStrategy.java

@@ -0,0 +1,67 @@
+package org.apache.maven.project.collector;
+
+/*
+ * 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 org.apache.maven.DefaultMaven;
+import org.apache.maven.execution.MavenExecutionRequest;
+import org.apache.maven.model.building.ModelSource;
+import org.apache.maven.model.building.UrlModelSource;
+import org.apache.maven.project.MavenProject;
+import org.apache.maven.project.ProjectBuilder;
+import org.apache.maven.project.ProjectBuildingException;
+import org.apache.maven.project.ProjectBuildingRequest;
+
+import javax.inject.Inject;
+import javax.inject.Named;
+import javax.inject.Singleton;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Strategy to collect projects for building when the Maven invocation is not in a folder that contains a pom.xml.
+ */
+@Named( "PomlessCollectionStrategy" )
+@Singleton
+public class PomlessCollectionStrategy
+    implements ProjectCollectionStrategy
+{
+    private final ProjectBuilder projectBuilder;
+
+    @Inject
+    public PomlessCollectionStrategy( ProjectBuilder projectBuilder )
+    {
+        this.projectBuilder = projectBuilder;
+    }
+
+    @Override
+    public List<MavenProject> collectProjects( final MavenExecutionRequest request )
+            throws ProjectBuildingException
+    {
+        ProjectBuildingRequest buildingRequest = request.getProjectBuildingRequest();
+        ModelSource modelSource = new UrlModelSource( DefaultMaven.class.getResource( "project/standalone.xml" ) );
+        MavenProject project = projectBuilder.build( modelSource,  buildingRequest ).getProject();
+        project.setExecutionRoot( true );
+        request.setProjectPresent( false );
+
+        final List<MavenProject> result = new ArrayList<>();
+        result.add( project );
+        return result;
+    }
+}

maven-core/src/main/java/org/apache/maven/project/collector/ProjectCollectionStrategy.java

@@ -0,0 +1,41 @@
+package org.apache.maven.project.collector;
+
+/*
+ * 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 org.apache.maven.execution.MavenExecutionRequest;
+import org.apache.maven.project.MavenProject;
+import org.apache.maven.project.ProjectBuildingException;
+
+import java.util.List;
+
+/**
+ * Describes strategies for finding projects that Maven could build.
+ */
+public interface ProjectCollectionStrategy
+{
+    /**
+     *
+     * @param request
+     * @return
+     * @throws ProjectBuildingException
+     */
+    List<MavenProject> collectProjects( final MavenExecutionRequest request )
+            throws ProjectBuildingException;
+}

maven-core/src/main/java/org/apache/maven/project/collector/ProjectsCollector.java

@@ -0,0 +1,43 @@
+package org.apache.maven.project.collector;
+
+/*
+ * 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 org.apache.maven.execution.MavenExecutionRequest;
+import org.apache.maven.project.MavenProject;
+import org.apache.maven.project.ProjectBuildingException;
+
+import java.io.File;
+import java.util.List;
+
+/**
+ * Facade to collect projects for a given set of pom.xml files.
+ */
+public interface ProjectsCollector
+{
+    /**
+     * Collect Maven projects from a list of POM files.
+     * @param projects List that will be filled with the found projects.
+     * @param files List of POM files.
+     * @param request The {@link MavenExecutionRequest}
+     * @throws ProjectBuildingException In case the POMs are not used.
+     */
+    void collectProjects( List<MavenProject> projects, List<File> files, MavenExecutionRequest request )
+            throws ProjectBuildingException;
+}

maven-core/src/main/java/org/apache/maven/project/collector/RequestPomCollectionStrategy.java

@@ -0,0 +1,57 @@
+package org.apache.maven.project.collector;
+
+/*
+ * 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 org.apache.maven.execution.MavenExecutionRequest;
+import org.apache.maven.project.MavenProject;
+import org.apache.maven.project.ProjectBuildingException;
+
+import javax.inject.Inject;
+import javax.inject.Named;
+import javax.inject.Singleton;
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Strategy to collect projects based on the <code>-f</code> CLI parameter or the pom.xml in the working directory.
+ */
+@Named( "RequestPomCollectionStrategy" )
+@Singleton
+public class RequestPomCollectionStrategy implements ProjectCollectionStrategy
+{
+    private final ProjectsCollector projectsCollector;
+
+    @Inject
+    public RequestPomCollectionStrategy( ProjectsCollector projectsCollector )
+    {
+        this.projectsCollector = projectsCollector;
+    }
+
+    @Override
+    public List<MavenProject> collectProjects( MavenExecutionRequest request ) throws ProjectBuildingException
+    {
+        List<File> files = Collections.singletonList( request.getPom().getAbsoluteFile() );
+        List<MavenProject> projects = new ArrayList<>();
+        projectsCollector.collectProjects( projects, files, request );
+        return projects;
+    }
+}

maven-core/src/test/java/org/apache/maven/AbstractCoreMavenComponentTestCase.java

@@ -116,6 +116,11 @@ public abstract class AbstractCoreMavenComponentTestCase
             .setPluginArtifactRepositories( getPluginArtifactRepositories() )
             .setGoals( Arrays.asList( "package" ) );
 
+        if ( pom != null )
+        {
+            request.setMultiModuleProjectDirectory( pom.getParentFile() );
+        }
+
         return request;
     }
 

maven-core/src/test/java/org/apache/maven/graph/DefaultGraphBuilderTest.java

@@ -19,37 +19,45 @@ package org.apache.maven.graph;
  * under the License.
  */
 
-import com.google.common.collect.ImmutableMap;
+import org.apache.maven.execution.BuildResumptionDataRepository;
 import org.apache.maven.execution.MavenExecutionRequest;
 import org.apache.maven.execution.MavenSession;
 import org.apache.maven.execution.ProjectDependencyGraph;
 import org.apache.maven.model.Dependency;
+import org.apache.maven.model.Parent;
 import org.apache.maven.model.building.Result;
+import org.apache.maven.model.locator.DefaultModelLocator;
+import org.apache.maven.model.locator.ModelLocator;
 import org.apache.maven.project.MavenProject;
 import org.apache.maven.project.ProjectBuilder;
 import org.apache.maven.project.ProjectBuildingRequest;
 import org.apache.maven.project.ProjectBuildingResult;
+import org.apache.maven.project.collector.DefaultProjectsCollector;
+import org.apache.maven.project.collector.MultiModuleCollectionStrategy;
+import org.apache.maven.project.collector.PomlessCollectionStrategy;
+import org.apache.maven.project.collector.ProjectsCollector;
+import org.apache.maven.project.collector.RequestPomCollectionStrategy;
 import org.codehaus.plexus.util.StringUtils;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 import org.junit.runners.Parameterized.Parameters;
-import org.mockito.InjectMocks;
-import org.mockito.Mock;
-import org.mockito.MockitoAnnotations;
 
 import java.io.File;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
+import static java.util.function.Function.identity;
 import static junit.framework.TestCase.assertEquals;
-import static org.apache.maven.execution.MavenExecutionRequest.*;
+import static org.apache.maven.execution.MavenExecutionRequest.REACTOR_MAKE_DOWNSTREAM;
 import static org.apache.maven.execution.MavenExecutionRequest.REACTOR_MAKE_UPSTREAM;
 import static org.apache.maven.graph.DefaultGraphBuilderTest.ScenarioBuilder.scenario;
 import static org.mockito.ArgumentMatchers.*;
@@ -59,22 +67,39 @@ import static org.mockito.Mockito.when;
 @RunWith( Parameterized.class )
 public class DefaultGraphBuilderTest
 {
+    /*
+    The multi-module structure in this project is displayed as follows:
+
+    module-parent
+    └─── module-independent     (without parent declaration)
+         module-a
+         module-b               (depends on module-a)
+         module-c
+         └─── module-c-1
+              module-c-2        (depends on module-b)
+     */
+    private static final String PARENT_MODULE = "module-parent";
     private static final String INDEPENDENT_MODULE = "module-independent";
     private static final String MODULE_A = "module-a";
-    private static final String MODULE_B = "module-b"; // depends on module-a
-    private static final String MODULE_C = "module-c"; // depends on module-b
+    private static final String MODULE_B = "module-b";
+    private static final String MODULE_C = "module-c";
+    private static final String MODULE_C_1 = "module-c-1";
+    private static final String MODULE_C_2 = "module-c-2";
 
-    @InjectMocks
     private DefaultGraphBuilder graphBuilder;
 
-    @Mock
-    private ProjectBuilder projectBuilder;
+    private final ProjectBuilder projectBuilder = mock( ProjectBuilder.class );
+    private final MavenSession session = mock( MavenSession.class );
+    private final MavenExecutionRequest mavenExecutionRequest = mock( MavenExecutionRequest.class );
 
-    @Mock
-    private MavenSession session;
+    private final ProjectsCollector projectsCollector = new DefaultProjectsCollector( projectBuilder );
 
-    @Mock
-    private MavenExecutionRequest mavenExecutionRequest;
+    // Not using mocks for these strategies - a mock would just copy the actual implementation.
+
+    private final ModelLocator modelLocator = new DefaultModelLocator();
+    private final PomlessCollectionStrategy pomlessCollectionStrategy = new PomlessCollectionStrategy( projectBuilder );
+    private final MultiModuleCollectionStrategy multiModuleCollectionStrategy = new MultiModuleCollectionStrategy( modelLocator, projectsCollector );
+    private final RequestPomCollectionStrategy requestPomCollectionStrategy = new RequestPomCollectionStrategy( projectsCollector );
 
     private Map<String, MavenProject> artifactIdProjectMap;
 
@@ -85,73 +110,85 @@ public class DefaultGraphBuilderTest
     private final String parameterResumeFrom;
     private final String parameterMakeBehavior;
     private final List<String> parameterExpectedResult;
+    private final File parameterRequestedPom;
 
     @Parameters(name = "{index}. {0}")
     public static Collection<Object[]> parameters()
     {
         return asList(
-                scenario( "Full reactor" )
-                        .expectResult( asList( INDEPENDENT_MODULE, MODULE_A, MODULE_B, MODULE_C ) ),
+                scenario( "Full reactor in order" )
+                        .expectResult( PARENT_MODULE, MODULE_C, MODULE_C_1, MODULE_A, MODULE_B, MODULE_C_2, INDEPENDENT_MODULE ),
                 scenario( "Selected project" )
-                        .selectedProjects( singletonList( MODULE_B ) )
-                        .expectResult( singletonList( MODULE_B ) ),
+                        .selectedProjects( MODULE_B )
+                        .expectResult( MODULE_B ),
                 scenario( "Excluded project" )
-                        .excludedProjects( singletonList( MODULE_B ) )
-                        .expectResult( asList( INDEPENDENT_MODULE, MODULE_A, MODULE_C ) ),
+                        .excludedProjects( MODULE_B )
+                        .expectResult( PARENT_MODULE, MODULE_C, MODULE_C_1, MODULE_A, MODULE_C_2, INDEPENDENT_MODULE ),
                 scenario( "Resuming from project" )
                         .resumeFrom( MODULE_B )
-                        .expectResult( asList( MODULE_B, MODULE_C ) ),
+                        .expectResult( MODULE_B, MODULE_C_2, INDEPENDENT_MODULE ),
                 scenario( "Selected project with also make dependencies" )
-                        .selectedProjects( singletonList( MODULE_C ) )
+                        .selectedProjects( MODULE_C_2 )
                         .makeBehavior( REACTOR_MAKE_UPSTREAM )
-                        .expectResult( asList( MODULE_A, MODULE_B, MODULE_C ) ),
+                        .expectResult( PARENT_MODULE, MODULE_C, MODULE_A, MODULE_B, MODULE_C_2 ),
                 scenario( "Selected project with also make dependents" )
-                        .selectedProjects( singletonList( MODULE_B ) )
+                        .selectedProjects( MODULE_B )
                         .makeBehavior( REACTOR_MAKE_DOWNSTREAM )
-                        .expectResult( asList( MODULE_B, MODULE_C ) ),
+                        .expectResult( MODULE_B, MODULE_C_2 ),
                 scenario( "Resuming from project with also make dependencies" )
                         .makeBehavior( REACTOR_MAKE_UPSTREAM )
-                        .resumeFrom( MODULE_C )
-                        .expectResult( asList( MODULE_A, MODULE_B, MODULE_C ) ),
-                scenario( "Selected project with resume from an also make dependency (MNG-4960 IT#1)" )
-                        .selectedProjects( singletonList( MODULE_C ) )
+                        .resumeFrom( MODULE_C_2 )
+                        .expectResult( PARENT_MODULE, MODULE_C, MODULE_A, MODULE_B, MODULE_C_2, INDEPENDENT_MODULE ),
+                scenario( "Selected project with resume from and also make dependency (MNG-4960 IT#1)" )
+                        .selectedProjects( MODULE_C_2 )
                         .resumeFrom( MODULE_B )
                         .makeBehavior( REACTOR_MAKE_UPSTREAM )
-                        .expectResult( asList( MODULE_A, MODULE_B, MODULE_C ) ),
-                scenario( "Selected project with resume from an also make dependent (MNG-4960 IT#2)" )
-                        .selectedProjects( singletonList( MODULE_B ) )
-                        .resumeFrom( MODULE_C )
+                        .expectResult( PARENT_MODULE, MODULE_C, MODULE_A, MODULE_B, MODULE_C_2 ),
+                scenario( "Selected project with resume from and also make dependent (MNG-4960 IT#2)" )
+                        .selectedProjects( MODULE_B )
+                        .resumeFrom( MODULE_C_2 )
                         .makeBehavior( REACTOR_MAKE_DOWNSTREAM )
-                        .expectResult( singletonList( MODULE_C ) ),
+                        .expectResult( MODULE_C_2 ),
                 scenario( "Excluding an also make dependency from selectedProject does take its transitive dependency" )
-                        .selectedProjects( singletonList( MODULE_C ) )
-                        .excludedProjects( singletonList( MODULE_B ) )
+                        .selectedProjects( MODULE_C_2 )
+                        .excludedProjects( MODULE_B )
                         .makeBehavior( REACTOR_MAKE_UPSTREAM )
-                        .expectResult( asList( MODULE_A, MODULE_C ) ),
+                        .expectResult( PARENT_MODULE, MODULE_C, MODULE_A, MODULE_C_2 ),
                 scenario( "Excluding an also make dependency from resumeFrom does take its transitive dependency" )
-                        .resumeFrom( MODULE_C )
-                        .excludedProjects( singletonList( MODULE_B ) )
+                        .resumeFrom( MODULE_C_2 )
+                        .excludedProjects( MODULE_B )
                         .makeBehavior( REACTOR_MAKE_UPSTREAM )
-                        .expectResult( asList( MODULE_A, MODULE_C ) ),
+                        .expectResult( PARENT_MODULE, MODULE_C, MODULE_A, MODULE_C_2, INDEPENDENT_MODULE ),
                 scenario( "Resume from exclude project downstream" )
                         .resumeFrom( MODULE_A )
-                        .excludedProjects( singletonList( MODULE_B ) )
-                        .expectResult( asList( MODULE_A, MODULE_C ) ),
+                        .excludedProjects( MODULE_B )
+                        .expectResult( MODULE_A, MODULE_C_2, INDEPENDENT_MODULE ),
                 scenario( "Exclude the project we are resuming from (as proposed in MNG-6676)" )
                         .resumeFrom( MODULE_B )
-                        .excludedProjects( singletonList( MODULE_B ) )
-                        .expectResult( singletonList( MODULE_C ) ),
+                        .excludedProjects( MODULE_B )
+                        .expectResult( MODULE_C_2, INDEPENDENT_MODULE ),
                 scenario( "Selected projects in wrong order are resumed correctly in order" )
-                        .selectedProjects( asList( MODULE_C, MODULE_B, MODULE_A ) )
+                        .selectedProjects( MODULE_C_2, MODULE_B, MODULE_A )
                         .resumeFrom( MODULE_B )
-                        .expectResult( asList( MODULE_B, MODULE_C ) ),
+                        .expectResult( MODULE_B, MODULE_C_2 ),
                 scenario( "Duplicate projects are filtered out" )
-                        .selectedProjects( asList( MODULE_A, MODULE_A ) )
-                        .expectResult( singletonList( MODULE_A ) )
+                        .selectedProjects( MODULE_A, MODULE_A )
+                        .expectResult( MODULE_A ),
+                scenario( "Select reactor by specific pom" )
+                        .requestedPom( MODULE_C )
+                        .expectResult( MODULE_C, MODULE_C_1, MODULE_C_2 ),
+                scenario( "Select reactor by specific pom with also make dependencies" )
+                        .requestedPom( MODULE_C )
+                        .makeBehavior( REACTOR_MAKE_UPSTREAM )
+                        .expectResult( PARENT_MODULE, MODULE_C, MODULE_C_1, MODULE_A, MODULE_B, MODULE_C_2 ),
+                scenario( "Select reactor by specific pom with also make dependents" )
+                        .requestedPom( MODULE_B )
+                        .makeBehavior( REACTOR_MAKE_DOWNSTREAM )
+                        .expectResult( MODULE_B, MODULE_C_2 )
         );
     }
 
-    public DefaultGraphBuilderTest( String description, List<String> selectedProjects, List<String> excludedProjects, String resumedFrom, String makeBehavior, List<String> expectedReactorProjects )
+    public DefaultGraphBuilderTest( String description, List<String> selectedProjects, List<String> excludedProjects, String resumedFrom, String makeBehavior, List<String> expectedReactorProjects, File requestedPom )
     {
         this.parameterDescription = description;
         this.parameterSelectedProjects = selectedProjects;
@@ -159,6 +196,7 @@ public class DefaultGraphBuilderTest
         this.parameterResumeFrom = resumedFrom;
         this.parameterMakeBehavior = makeBehavior;
         this.parameterExpectedResult = expectedReactorProjects;
+        this.parameterRequestedPom = requestedPom;
     }
 
     @Test
@@ -171,6 +209,7 @@ public class DefaultGraphBuilderTest
         when( mavenExecutionRequest.getSelectedProjects() ).thenReturn( selectedProjects );
         when( mavenExecutionRequest.getExcludedProjects() ).thenReturn( excludedProjects );
         when( mavenExecutionRequest.getMakeBehavior() ).thenReturn( parameterMakeBehavior );
+        when( mavenExecutionRequest.getPom() ).thenReturn( parameterRequestedPom );
         if ( StringUtils.isNotEmpty( parameterResumeFrom ) )
         {
             when( mavenExecutionRequest.getResumeFrom() ).thenReturn( ":" + parameterResumeFrom );
@@ -190,40 +229,47 @@ public class DefaultGraphBuilderTest
     @Before
     public void before() throws Exception
     {
-        MockitoAnnotations.initMocks( this );
+        graphBuilder = new DefaultGraphBuilder(
+                mock( BuildResumptionDataRepository.class ),
+                pomlessCollectionStrategy,
+                multiModuleCollectionStrategy,
+                requestPomCollectionStrategy
+        );
 
-        ProjectBuildingRequest projectBuildingRequest = mock( ProjectBuildingRequest.class );
-        ProjectBuildingResult projectBuildingResult1 = mock( ProjectBuildingResult.class );
-        ProjectBuildingResult projectBuildingResult2 = mock( ProjectBuildingResult.class );
-        ProjectBuildingResult projectBuildingResult3 = mock( ProjectBuildingResult.class );
-        ProjectBuildingResult projectBuildingResult4 = mock( ProjectBuildingResult.class );
-        MavenProject projectIndependentModule = getMavenProject( "independent-module" );
-        MavenProject projectModuleA = getMavenProject( "module-a" );
-        MavenProject projectModuleB = getMavenProject( "module-b" );
-        MavenProject projectModuleC = getMavenProject( "module-c" );
-        projectModuleB.setDependencies( singletonList( toDependency( projectModuleA) ) );
-        projectModuleC.setDependencies( singletonList( toDependency( projectModuleB) ) );
+        // Create projects
+        MavenProject projectParent = getMavenProject( PARENT_MODULE );
+        MavenProject projectIndependentModule = getMavenProject( INDEPENDENT_MODULE );
+        MavenProject projectModuleA = getMavenProject( MODULE_A, projectParent );
+        MavenProject projectModuleB = getMavenProject( MODULE_B, projectParent );
+        MavenProject projectModuleC = getMavenProject( MODULE_C, projectParent );
+        MavenProject projectModuleC1 = getMavenProject( MODULE_C_1, projectModuleC );
+        MavenProject projectModuleC2 = getMavenProject( MODULE_C_2, projectModuleC );
 
+        artifactIdProjectMap = Stream.of( projectParent, projectIndependentModule, projectModuleA, projectModuleB, projectModuleC, projectModuleC1, projectModuleC2 )
+                .collect( Collectors.toMap( MavenProject::getArtifactId, identity() ) );
+
+        // Set dependencies and modules
+        projectModuleB.setDependencies( singletonList( toDependency( projectModuleA ) ) );
+        projectModuleC2.setDependencies( singletonList( toDependency( projectModuleB ) ) );
+        projectParent.setCollectedProjects( asList( projectIndependentModule, projectModuleA, projectModuleB, projectModuleC, projectModuleC1, projectModuleC2 ) );
+        projectModuleC.setCollectedProjects( asList( projectModuleC1, projectModuleC2 ) );
+
+        // Set up needed mocks
         when( session.getRequest() ).thenReturn( mavenExecutionRequest );
         when( session.getProjects() ).thenReturn( null ); // needed, otherwise it will be an empty list by default
+        when( mavenExecutionRequest.getProjectBuildingRequest() ).thenReturn( mock( ProjectBuildingRequest.class ) );
+        List<ProjectBuildingResult> projectBuildingResults = createProjectBuildingResultMocks( artifactIdProjectMap.values() );
+        when( projectBuilder.build( anyList(), anyBoolean(), any( ProjectBuildingRequest.class ) ) ).thenReturn( projectBuildingResults );
+    }
 
-        when( mavenExecutionRequest.getProjectBuildingRequest() ).thenReturn( projectBuildingRequest );
-        when( mavenExecutionRequest.getPom() ).thenReturn( new File( "/tmp/unit-test" ) );
-
-        when( projectBuildingResult1.getProject() ).thenReturn( projectIndependentModule );
-        when( projectBuildingResult2.getProject() ).thenReturn( projectModuleA );
-        when( projectBuildingResult3.getProject() ).thenReturn( projectModuleB );
-        when( projectBuildingResult4.getProject() ).thenReturn( projectModuleC );
-
-        when( projectBuilder.build( anyList(), anyBoolean(), any( ProjectBuildingRequest.class ) ) )
-                .thenReturn( asList( projectBuildingResult1, projectBuildingResult2, projectBuildingResult3, projectBuildingResult4 ) );
-
-        artifactIdProjectMap = ImmutableMap.of(
-                INDEPENDENT_MODULE, projectIndependentModule,
-                MODULE_A, projectModuleA,
-                MODULE_B, projectModuleB,
-                MODULE_C, projectModuleC
-        );
+    private MavenProject getMavenProject( String artifactId, MavenProject parentProject )
+    {
+        MavenProject project = getMavenProject( artifactId );
+        Parent parent = new Parent();
+        parent.setGroupId( parentProject.getGroupId() );
+        parent.setArtifactId( parentProject.getArtifactId() );
+        project.getModel().setParent( parent );
+        return project;
     }
 
     private MavenProject getMavenProject( String artifactId )
@@ -232,6 +278,8 @@ public class DefaultGraphBuilderTest
         mavenProject.setGroupId( "unittest" );
         mavenProject.setArtifactId( artifactId );
         mavenProject.setVersion( "1.0" );
+        mavenProject.setPomFile( new File ( artifactId, "pom.xml" ) );
+        mavenProject.setCollectedProjects( new ArrayList<>() );
         return mavenProject;
     }
 
@@ -244,6 +292,17 @@ public class DefaultGraphBuilderTest
         return dependency;
     }
 
+    private List<ProjectBuildingResult> createProjectBuildingResultMocks( Collection<MavenProject> projects )
+    {
+        return projects.stream()
+                .map( project -> {
+                    ProjectBuildingResult result = mock( ProjectBuildingResult.class );
+                    when( result.getProject() ).thenReturn( project );
+                    return result;
+                } )
+                .collect( Collectors.toList() );
+    }
+
     static class ScenarioBuilder
     {
         private String description;
@@ -251,6 +310,7 @@ public class DefaultGraphBuilderTest
         private List<String> excludedProjects = emptyList();
         private String resumeFrom = "";
         private String makeBehavior = "";
+        private File requestedPom = new File( PARENT_MODULE, "pom.xml" );
 
         private ScenarioBuilder() { }
 
@@ -261,15 +321,15 @@ public class DefaultGraphBuilderTest
             return scenarioBuilder;
         }
 
-        public ScenarioBuilder selectedProjects( List<String> selectedProjects )
+        public ScenarioBuilder selectedProjects( String... selectedProjects )
         {
-            this.selectedProjects = selectedProjects;
+            this.selectedProjects = asList( selectedProjects );
             return this;
         }
 
-        public ScenarioBuilder excludedProjects( List<String> excludedProjects )
+        public ScenarioBuilder excludedProjects( String... excludedProjects )
         {
-            this.excludedProjects = excludedProjects;
+            this.excludedProjects = asList( excludedProjects );
             return this;
         }
 
@@ -285,10 +345,16 @@ public class DefaultGraphBuilderTest
             return this;
         }
 
-        public Object[] expectResult( List<String> expectedReactorProjects )
+        public ScenarioBuilder requestedPom( String requestedPom )
+        {
+            this.requestedPom = new File( requestedPom, "pom.xml" );
+            return this;
+        }
+
+        public Object[] expectResult( String... expectedReactorProjects )
         {
             return new Object[] {
-                    description, selectedProjects, excludedProjects, resumeFrom, makeBehavior, expectedReactorProjects
+                    description, selectedProjects, excludedProjects, resumeFrom, makeBehavior, asList( expectedReactorProjects ), requestedPom
             };
         }
     }