Added tests for traversal order when using SceneGraphVisitor.

jme3-core/src/test/java/com/jme3/scene/SceneGraphTraversalTest.java

@@ -0,0 +1,175 @@
+/*
+ * Copyright (c) 2009-2019 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
+ *   may be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.jme3.scene;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import org.junit.Test;
+
+/**
+ * Tests for traversal order when using SceneGraphVisitor
+ * with Spatial.depthFirstTraversal() and Spatial.breadthFirstTraversal().
+ *
+ * Related: Pull Request #1012 at GitHub
+ *
+ * @author 1000ml/FennelFetish (https://github.com/FennelFetish)
+ */
+public class SceneGraphTraversalTest {
+
+    private static Node buildTestSceneGraph() {
+        Node root       = new Node("Root");
+
+        Node n1         = new Node("N1");
+        Node n11        = new Node("N11");
+        Node n111       = new Node("N111");
+        Geometry g112   = new Geometry("G112");
+
+        Node n2         = new Node("N2");
+        Node n21        = new Node("N21");
+        Node n211       = new Node("N211");
+        Geometry g212   = new Geometry("G212");
+
+        root.attachChild(n1);
+        n1.attachChild(n11);
+        n11.attachChild(n111);
+        n11.attachChild(g112);
+
+        root.attachChild(n2);
+        n2.attachChild(n21);
+        n21.attachChild(n211);
+        n21.attachChild(g212);
+
+        /* Graph:
+                Root
+                    N1
+                        N11
+                            N111
+                            G112
+                    N2
+                        N21
+                            N211
+                            G212
+        */
+
+        return root;
+    }
+
+
+    private static final List<String> EXPECTED_ORDER_DFS_PRE;
+    private static final List<String> EXPECTED_ORDER_DFS_POST;
+    private static final List<String> EXPECTED_ORDER_BFS;
+
+    static {
+        List<String> expectedDfsPre = new ArrayList<>();
+        expectedDfsPre.add("Root");
+        expectedDfsPre.add("N1");
+        expectedDfsPre.add("N11");
+        expectedDfsPre.add("N111");
+        expectedDfsPre.add("G112");
+        expectedDfsPre.add("N2");
+        expectedDfsPre.add("N21");
+        expectedDfsPre.add("N211");
+        expectedDfsPre.add("G212");
+        EXPECTED_ORDER_DFS_PRE = Collections.unmodifiableList(expectedDfsPre);
+
+        List<String> expectedDfsPost = new ArrayList<>();
+        expectedDfsPost.add("N111");
+        expectedDfsPost.add("G112");
+        expectedDfsPost.add("N11");
+        expectedDfsPost.add("N1");
+        expectedDfsPost.add("N211");
+        expectedDfsPost.add("G212");
+        expectedDfsPost.add("N21");
+        expectedDfsPost.add("N2");
+        expectedDfsPost.add("Root");
+        EXPECTED_ORDER_DFS_POST = Collections.unmodifiableList(expectedDfsPost);
+
+        List<String> expectedBfs = new ArrayList<>();
+        expectedBfs.add("Root");
+        expectedBfs.add("N1");
+        expectedBfs.add("N2");
+        expectedBfs.add("N11");
+        expectedBfs.add("N21");
+        expectedBfs.add("N111");
+        expectedBfs.add("G112");
+        expectedBfs.add("N211");
+        expectedBfs.add("G212");
+        EXPECTED_ORDER_BFS = Collections.unmodifiableList(expectedBfs);
+    }
+
+
+    private static class NameListVisitor implements SceneGraphVisitor {
+        private final List<String> namesInOrder = new ArrayList<>();
+
+        @Override
+        public void visit(Spatial spatial) {
+            namesInOrder.add(spatial.getName());
+        }
+    }
+
+    
+    @Test
+    public void testDFSPreOrder() {
+        NameListVisitor visitor = new NameListVisitor();
+        buildTestSceneGraph().depthFirstTraversal(visitor, Spatial.DFSMode.PRE_ORDER);
+
+        assertThat(visitor.namesInOrder, is(EXPECTED_ORDER_DFS_PRE));
+    }
+
+    @Test
+    public void testDFSPostOrder() {
+        NameListVisitor visitor = new NameListVisitor();
+        buildTestSceneGraph().depthFirstTraversal(visitor, Spatial.DFSMode.POST_ORDER);
+
+        assertThat(visitor.namesInOrder, is(EXPECTED_ORDER_DFS_POST));
+    }
+
+    @Test
+    public void testDFSDefaultOrder() {
+        NameListVisitor visitor = new NameListVisitor();
+        buildTestSceneGraph().depthFirstTraversal(visitor);
+
+        assertThat(visitor.namesInOrder, is(EXPECTED_ORDER_DFS_POST));
+    }
+
+    @Test
+    public void testBFS() {
+        NameListVisitor visitor = new NameListVisitor();
+        buildTestSceneGraph().breadthFirstTraversal(visitor);
+
+        assertThat(visitor.namesInOrder, is(EXPECTED_ORDER_BFS));
+    }
+}