[MNG-6357] Dependency order should be nearest first

maven-core/pom.xml

@@ -185,6 +185,12 @@ under the License.
       <artifactId>plexus-testing</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.apache.maven.resolver</groupId>
+      <artifactId>maven-resolver-test-util</artifactId>
+      <version>${resolverVersion}</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>

maven-core/src/main/java/org/apache/maven/RepositoryUtils.java

@@ -26,6 +26,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.TreeMap;
 
 import org.apache.maven.artifact.handler.ArtifactHandler;
 import org.apache.maven.artifact.handler.DefaultArtifactHandler;
@@ -112,6 +113,25 @@ public static org.apache.maven.artifact.Artifact toArtifact( Artifact artifact )
     public static void toArtifacts( Collection<org.apache.maven.artifact.Artifact> artifacts,
                                     Collection<? extends DependencyNode> nodes, List<String> trail,
                                     DependencyFilter filter )
+    {
+        Map<Integer, List<org.apache.maven.artifact.Artifact>> artifactsByDepth = new TreeMap<>();
+
+        List<org.apache.maven.artifact.Artifact> firstLevelArtifacts = new ArrayList<>( nodes.size() );
+        // we know there are at least direct dependencies
+        artifactsByDepth.put( 1, firstLevelArtifacts );
+
+        toArtifacts( artifactsByDepth, 1, nodes, trail, filter );
+
+        // list of artifacts ordered by depth level
+        for ( List<org.apache.maven.artifact.Artifact> artifactsInDepth : artifactsByDepth.values() )
+        {
+            artifacts.addAll( artifactsInDepth );
+        }
+    }
+
+    private static void toArtifacts( Map<Integer, List<org.apache.maven.artifact.Artifact>> artifactsByDepth,
+                                     int currentDepth, Collection<? extends DependencyNode> nodes, List<String> trail,
+                                     DependencyFilter filter )
     {
         for ( DependencyNode node : nodes )
         {
@@ -124,10 +144,18 @@ public static void toArtifacts( Collection<org.apache.maven.artifact.Artifact> a
             if ( filter == null || filter.accept( node, Collections.emptyList() ) )
             {
                 artifact.setDependencyTrail( nodeTrail );
-                artifacts.add( artifact );
+
+                // add artifact in the list of the current depth
+                List<org.apache.maven.artifact.Artifact> artifactsCurrentDepth = artifactsByDepth.get( currentDepth );
+                if ( artifactsCurrentDepth == null )
+                {
+                    artifactsCurrentDepth = new ArrayList<>();
+                    artifactsByDepth.put( currentDepth, artifactsCurrentDepth );
+                }
+                artifactsCurrentDepth.add( artifact );
             }
 
-            toArtifacts( artifacts, node.getChildren(), nodeTrail, filter );
+            toArtifacts( artifactsByDepth, currentDepth + 1, node.getChildren(), nodeTrail, filter );
         }
     }
 

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

@@ -0,0 +1,114 @@
+package org.apache.maven;
+
+/*
+ * 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.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.fail;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import org.eclipse.aether.graph.DependencyFilter;
+import org.eclipse.aether.graph.DependencyNode;
+import org.eclipse.aether.internal.test.util.DependencyGraphParser;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Test RepositoryUtils
+ *
+ * @author Gabriel Belingueres
+ */
+public class RepositoryUtilsTest
+{
+
+    @Test
+    public void testToArtifactsCollectionOrderedByNodeDepth()
+    {
+        Collection<org.apache.maven.artifact.Artifact> artifacts = new ArrayList<>();
+
+        DependencyNode root = createDependencyTree();
+
+        List<String> trail = new ArrayList<>();
+        DependencyFilter filter = null;
+
+        RepositoryUtils.toArtifacts( artifacts, root.getChildren(), trail, filter );
+
+        String expected =
+            "[gid:zlevel1:jar:1:, gid:ylevel1:jar:1:, gid:xlevel1:jar:1:, gid:alevel2:jar:1:, gid:blevel2:jar:1:, gid:clevel2:jar:1:, gid:alevel3:jar:1:]";
+        assertEquals( expected, artifacts.toString() );
+    }
+
+    @Test
+    public void testToArtifactsCollectionOrderedByNodeDepthWithFilter()
+    {
+        Collection<org.apache.maven.artifact.Artifact> artifacts = new ArrayList<>();
+
+        DependencyNode root = createDependencyTree();
+
+        List<String> trail = new ArrayList<>();
+        DependencyFilter filter = new DependencyFilter()
+        {
+            @Override
+            public boolean accept( DependencyNode node, List<DependencyNode> parents )
+            {
+                // accept node if artifactId does NOT contain "level2"
+                return !node.getArtifact().getArtifactId().contains( "level2" );
+            }
+        };
+
+        RepositoryUtils.toArtifacts( artifacts, root.getChildren(), trail, filter );
+
+        String expected =
+            "[gid:zlevel1:jar:1:, gid:ylevel1:jar:1:, gid:xlevel1:jar:1:, gid:alevel3:jar:1:]";
+        assertEquals( expected, artifacts.toString() );
+    }
+
+    /**
+     * Create a dependency tree.
+     *
+     * @return the root node or the tree.
+     */
+    private DependencyNode createDependencyTree()
+    {
+        String LS = System.lineSeparator();
+        DependencyGraphParser parser = new DependencyGraphParser();
+        String dependencyGraph =
+                        "gid:root:1" + LS +
+                        "+- gid:zlevel1:1" + LS +
+                        "|  \\- gid:alevel2:1" + LS +
+                        "\\- gid:ylevel1:1" + LS +
+                        "|  \\- gid:blevel2:1" + LS +
+                        "|      \\- gid:alevel3:1" + LS +
+                        "\\- gid:xlevel1:1" + LS +
+                        "   \\- gid:clevel2:1" + LS;
+
+        try
+        {
+            return parser.parseLiteral( dependencyGraph );
+        }
+        catch ( IOException e )
+        {
+            fail( "Failed the parsing of the dependency node graph" );
+        }
+        return null;
+    }
+
+}