[1.9.x][MRESOLVER-483] Fix path concatenation logic (#420)

As iterator may have more, but no file check is done

---

https://issues.apache.org/jira/browse/MRESOLVER-483

maven-resolver-util/src/main/java/org/eclipse/aether/util/graph/visitor/AbstractDepthFirstNodeListGenerator.java

@@ -135,10 +135,10 @@ public String getClassPath() {
             if (node.getDependency() != null) {
                 Artifact artifact = node.getDependency().getArtifact();
                 if (artifact.getFile() != null) {
-                    buffer.append(artifact.getFile().getAbsolutePath());
-                    if (it.hasNext()) {
+                    if (buffer.length() != 0) {
                         buffer.append(File.pathSeparatorChar);
                     }
+                    buffer.append(artifact.getFile().getAbsolutePath());
                 }
             }
         }

maven-resolver-util/src/test/java/org/eclipse/aether/util/graph/visitor/AbstractDepthFirstNodeListGeneratorTestSupport.java

@@ -0,0 +1,87 @@
+/*
+ * 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.eclipse.aether.util.graph.visitor;
+
+import java.io.File;
+import java.util.List;
+
+import org.eclipse.aether.graph.DependencyNode;
+import org.eclipse.aether.graph.DependencyVisitor;
+import org.eclipse.aether.internal.test.util.DependencyGraphParser;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public abstract class AbstractDepthFirstNodeListGeneratorTestSupport {
+
+    protected DependencyNode parse(String resource) throws Exception {
+        return new DependencyGraphParser("visitor/ordered-list/").parseResource(resource);
+    }
+
+    protected void assertSequence(List<DependencyNode> actual, String... expected) {
+        assertEquals(actual.toString(), expected.length, actual.size());
+        for (int i = 0; i < expected.length; i++) {
+            DependencyNode node = actual.get(i);
+            assertEquals(
+                    actual.toString(),
+                    expected[i],
+                    node.getDependency().getArtifact().getArtifactId());
+        }
+    }
+
+    @Test
+    public void testClasspath() throws Exception {
+        DependencyNode root = parse("simple.txt");
+
+        PreorderNodeListGenerator visitor = new PreorderNodeListGenerator();
+        root.accept(visitor);
+
+        assertEquals(visitor.getClassPath(), "");
+    }
+
+    @Test
+    public void testFullyResolverClasspath() throws Exception {
+        DependencyNode root = parse("simple.txt");
+
+        DependencyVisitor fileSetter = new DependencyVisitor() {
+            @Override
+            public boolean visitEnter(DependencyNode node) {
+                node.setArtifact(
+                        node.getArtifact().setFile(new File(node.getArtifact().getArtifactId())));
+                return true;
+            }
+
+            @Override
+            public boolean visitLeave(DependencyNode node) {
+                return true;
+            }
+        };
+        root.accept(fileSetter);
+
+        PreorderNodeListGenerator visitor = new PreorderNodeListGenerator();
+        root.accept(visitor);
+
+        String classpath = visitor.getClassPath();
+        assertEquals(5, classpath.split(File.pathSeparator).length);
+        for (File file : visitor.getFiles()) {
+            assertTrue("missing: " + file, classpath.contains(file.getAbsolutePath()));
+        }
+    }
+}

maven-resolver-util/src/test/java/org/eclipse/aether/util/graph/visitor/PostorderNodeListGeneratorTest.java

@@ -18,30 +18,12 @@
  */
 package org.eclipse.aether.util.graph.visitor;
 
-import java.util.List;
-
 import org.eclipse.aether.graph.DependencyNode;
-import org.eclipse.aether.internal.test.util.DependencyGraphParser;
 import org.junit.Test;
 
 import static org.junit.Assert.*;
 
-public class PostorderNodeListGeneratorTest {
-
-    private DependencyNode parse(String resource) throws Exception {
-        return new DependencyGraphParser("visitor/ordered-list/").parseResource(resource);
-    }
-
-    private void assertSequence(List<DependencyNode> actual, String... expected) {
-        assertEquals(actual.toString(), expected.length, actual.size());
-        for (int i = 0; i < expected.length; i++) {
-            DependencyNode node = actual.get(i);
-            assertEquals(
-                    actual.toString(),
-                    expected[i],
-                    node.getDependency().getArtifact().getArtifactId());
-        }
-    }
+public class PostorderNodeListGeneratorTest extends AbstractDepthFirstNodeListGeneratorTestSupport {
 
     @Test
     public void testOrdering() throws Exception {

maven-resolver-util/src/test/java/org/eclipse/aether/util/graph/visitor/PreorderNodeListGeneratorTest.java

@@ -18,31 +18,12 @@
  */
 package org.eclipse.aether.util.graph.visitor;
 
-import java.util.List;
-
 import org.eclipse.aether.graph.DependencyNode;
-import org.eclipse.aether.internal.test.util.DependencyGraphParser;
 import org.junit.Test;
 
 import static org.junit.Assert.*;
 
-public class PreorderNodeListGeneratorTest {
-
-    private DependencyNode parse(String resource) throws Exception {
-        return new DependencyGraphParser("visitor/ordered-list/").parseResource(resource);
-    }
-
-    private void assertSequence(List<DependencyNode> actual, String... expected) {
-        assertEquals(actual.toString(), expected.length, actual.size());
-        for (int i = 0; i < expected.length; i++) {
-            DependencyNode node = actual.get(i);
-            assertEquals(
-                    actual.toString(),
-                    expected[i],
-                    node.getDependency().getArtifact().getArtifactId());
-        }
-    }
-
+public class PreorderNodeListGeneratorTest extends AbstractDepthFirstNodeListGeneratorTestSupport {
     @Test
     public void testOrdering() throws Exception {
         DependencyNode root = parse("simple.txt");