Broken KdNode equals and compareTo causes the KdTree not to return all valid results

src/com/jwetherell/algorithms/data_structures/KdTree.java

@@ -588,7 +588,8 @@ public boolean equals(Object obj) {
          */
         @Override
         public int compareTo(KdNode o) {
-            return compareTo(depth, k, this.id, o.id);
+            int depthCompare = Integer.compare(this.depth, o.depth);
+            return depthCompare != 0 ? depthCompare : this.id.compareTo(o.id);
         }
 
         /**

test/com/jwetherell/algorithms/data_structures/test/KdTreeTests.java

@@ -1,6 +1,7 @@
 package com.jwetherell.algorithms.data_structures.test;
 
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertEquals;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -36,9 +37,9 @@ public void testKdTree() {
         XYZPoint search = new XYZPoint(1, 4);
         result = kdTree.nearestNeighbourSearch(4, search);
         assertTrue("K-D Tree query error. query=(k=4, p=(1, 4)) returned="+result, (result.contains(p1) &&
-                                                                                    result.contains(p2) &&
-                                                                                    result.contains(p4) &&
-                                                                                    result.contains(p6))
+                result.contains(p2) &&
+                result.contains(p4) &&
+                result.contains(p6))
         );
 
         kdTree.remove(p6);
@@ -67,6 +68,21 @@ public void testKdTree_as_iterable() {
         KdTree<XYZPoint> kdTree = new KdTree<XYZPoint>(points);
 
         for (final XYZPoint p : kdTree)
-           assertTrue(kdTree.contains(p));
+            assertTrue(kdTree.contains(p));
+    }
+
+    @Test
+    public void testKdTreeNearestNeighbour() {
+        List<XYZPoint> points = new ArrayList<XYZPoint>();
+        XYZPoint p1 = new XYZPoint(0, 0, 0);
+        points.add(p1);
+        XYZPoint p2 = new XYZPoint(-1, 0, 1);
+        points.add(p2);
+        XYZPoint p3 = new XYZPoint(2, 0, -2);
+        points.add(p3);
+        KdTree<XYZPoint> kdTree = new KdTree<XYZPoint>(points);
+
+        Collection<XYZPoint> result = kdTree.nearestNeighbourSearch(3, p1);
+        assertEquals("K-D Tree query error. expected all points to be returned" + result, 3, result.size());
     }
 }