LUCENE-7212: Add tests for encoding/decoding.

lucene/spatial3d/src/java/org/apache/lucene/spatial3d/Geo3DDocValuesField.java

@@ -52,10 +52,10 @@ public class Geo3DDocValuesField extends Field {
   // If we plug in maximum for value, we should get 0x1FFFFF.
   // So, 0x1FFFFF = Math.floor((maximum - minimum) * factor + 0.5)
   // We factor out the 0.5 and Math.floor by stating instead:
-  // 0x200000 = (maximum - minimum) * factor
-  // So, factor = 0x200000 / (maximum - minimum)
+  // 0x1FFFFF = (maximum - minimum) * factor
+  // So, factor = 0x1FFFFF / (maximum - minimum)
 
-  private final static double inverseMaximumValue = 1.0 / (double)(0x200000);
+  private final static double inverseMaximumValue = 1.0 / (double)(0x1FFFFF);
   
   private final static double inverseXFactor = (PlanetModel.WGS84.getMaximumXValue() - PlanetModel.WGS84.getMinimumXValue()) * inverseMaximumValue;
   private final static double inverseYFactor = (PlanetModel.WGS84.getMaximumYValue() - PlanetModel.WGS84.getMinimumYValue()) * inverseMaximumValue;
@@ -108,7 +108,7 @@ public class Geo3DDocValuesField extends Field {
    * @throws IllegalArgumentException if the point is out of bounds
    */
   public void setLocationValue(final GeoPoint point) {
-    setLocationValue(point.x, point.y, point.z);
+    fieldsData = Long.valueOf(encodePoint(point));
   }
 
   /**
@@ -119,14 +119,31 @@ public class Geo3DDocValuesField extends Field {
    * @throws IllegalArgumentException if x, y, or z are out of bounds
    */
   public void setLocationValue(final double x, final double y, final double z) {
+    fieldsData = Long.valueOf(encodePoint(x, y, z));
+  }
+  
+  /** Encode a point.
+   * @param point is the point
+   * @return the encoded long
+   */
+  public static long encodePoint(final GeoPoint point) {
+    return encodePoint(point.x, point.y, point.z);
+  }
+
+  /** Encode a point.
+   * @param x is the x value
+   * @param y is the y value
+   * @param z is the z value
+   * @return the encoded long
+   */
+  public static long encodePoint(final double x, final double y, final double z) {
     int XEncoded = encodeX(x);
     int YEncoded = encodeY(y);
     int ZEncoded = encodeZ(z);
-    fieldsData = Long.valueOf(
+    return
       (((long)(XEncoded & 0x1FFFFF)) << 42) |
       (((long)(YEncoded & 0x1FFFFF)) << 21) |
-      ((long)(ZEncoded & 0x1FFFFF))
-      );
+      ((long)(ZEncoded & 0x1FFFFF));
   }
 
   /** Decode GeoPoint value from long docvalues value.

lucene/spatial3d/src/test/org/apache/lucene/spatial3d/TestGeo3DDocValues.java

@@ -0,0 +1,53 @@
+/*
+ * 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.apache.lucene.spatial3d;
+
+import org.apache.lucene.spatial3d.geom.GeoPoint;
+import org.apache.lucene.spatial3d.geom.PlanetModel;
+
+import org.apache.lucene.util.LuceneTestCase;
+import org.apache.lucene.util.TestUtil;
+
+public class TestGeo3DDocValues extends LuceneTestCase {
+
+  public void testBasic() throws Exception {
+    checkPointEncoding(0.0, 0.0);
+    checkPointEncoding(45.0, 72.0);
+    checkPointEncoding(-45.0, -100.0);
+    final int testAmt = TestUtil.nextInt(random(), 1000, 2000);
+    for (int i = 0; i < testAmt; i++) {
+      checkPointEncoding(random().nextDouble() * 180.0 - 90.0, random().nextDouble() * 360.0 - 180.0);
+    }
+  }
+    
+  void checkPointEncoding(final double latitude, final double longitude) {
+    final GeoPoint point = new GeoPoint(PlanetModel.WGS84, Geo3DUtil.fromDegrees(latitude), Geo3DUtil.fromDegrees(longitude));
+    long pointValue = Geo3DDocValuesField.encodePoint(point);
+    final double x = Geo3DDocValuesField.decodeXValue(pointValue);
+    final double y = Geo3DDocValuesField.decodeYValue(pointValue);
+    final double z = Geo3DDocValuesField.decodeZValue(pointValue);
+    final GeoPoint pointR = new GeoPoint(x,y,z);
+    // Check whether stable
+    pointValue = Geo3DDocValuesField.encodePoint(x, y, z);
+    assertEquals(x, Geo3DDocValuesField.decodeXValue(pointValue), 0.0);
+    assertEquals(y, Geo3DDocValuesField.decodeYValue(pointValue), 0.0);
+    assertEquals(z, Geo3DDocValuesField.decodeZValue(pointValue), 0.0);
+    // Check whether has some relationship with original point
+    assertEquals(0.0, point.arcDistance(pointR), 0.02);
+  }
+  
+}