JAVA-612: Properly define equals and hashCode for DBRefBase

Author: jyemin

src/main/com/mongodb/DBRefBase.java

@@ -85,16 +85,23 @@ public DB getDB() {
     }
 
     @Override
-    public boolean equals(Object obj) {
-        if (obj == this)
-            return true;
-
-        if (obj instanceof DBRefBase) {
-            DBRefBase ref = (DBRefBase) obj;
-            if (_ns.equals(ref.getRef()) && _id.equals(ref.getId()))
-                return true;
-        }
-        return false;
+    public boolean equals(final Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        final DBRefBase dbRefBase = (DBRefBase) o;
+
+        if (_id != null ? !_id.equals(dbRefBase._id) : dbRefBase._id != null) return false;
+        if (_ns != null ? !_ns.equals(dbRefBase._ns) : dbRefBase._ns != null) return false;
+
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = _id != null ? _id.hashCode() : 0;
+        result = 31 * result + (_ns != null ? _ns.hashCode() : 0);
+        return result;
     }
 
     final Object _id;

src/test/com/mongodb/DBRefTest.java

@@ -16,14 +16,15 @@
 
 package com.mongodb;
 
-import java.net.*;
-import java.util.*;
+import com.mongodb.util.TestCase;
+import org.bson.BSONDecoder;
+import org.bson.BasicBSONDecoder;
+import org.bson.types.ObjectId;
+import org.testng.annotations.Test;
 
-import org.bson.*;
-import org.bson.types.*;
-import org.testng.annotations.*;
-
-import com.mongodb.util.*;
+import java.net.UnknownHostException;
+import java.util.ArrayList;
+import java.util.List;
 
 public class DBRefTest extends TestCase {
 
@@ -38,6 +39,16 @@ public DBRefTest() {
         }
     }
 
+    @Test(groups = {"basic"})
+    public void testEqualsAndHashCode() {
+       DBRef ref = new DBRef(_db, "foo.bar", 4);
+       DBRef other = new DBRef(_db, "foo.bar", 4);
+       assertEquals(ref, ref);
+       assertEquals(ref, other);
+       assertNotEquals(ref, new DBRefBase(_db, "foo.bar", 4));
+       assertEquals(ref.hashCode(), other.hashCode());
+    }
+
     @Test(groups = {"basic"})
     public void testDBRefBaseToString(){