CursorIteratorTest to use Guava comparator (lmdbjava#7)

bp-alex · bp-alex · commit 2b307006b5b6 · 2017-07-15T13:32:40.000+10:00
This is an example of how users could pass their own Comparator,
subject of course to the comparator reflecting the key order returned
by LMDB by Cursor previous / next invocations (if a comparator would
result in a different key order than LMDB will return from its B+ tree
index, we cannot efficiently use LMDB to iterate the key space).
diff --git a/src/test/java/org/lmdbjava/CursorIteratorTest.java b/src/test/java/org/lmdbjava/CursorIteratorTest.java
@@ -20,6 +20,7 @@
 
 package org.lmdbjava;
 
+import com.google.common.primitives.UnsignedBytes;
 import java.io.File;
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -269,6 +270,24 @@ public void openClosedBackwardTest() {
     verify(openClosedBackward(bb(8), bb(4)), 6, 4);
   }
 
+  @Test
+  public void openClosedBackwardTestWithGuava() {
+    final Comparator<byte[]> guava = UnsignedBytes.lexicographicalComparator();
+    final Comparator<ByteBuffer> comparator = (bb1, bb2) -> {
+      final byte[] array1 = new byte[bb1.remaining()];
+      final byte[] array2 = new byte[bb2.remaining()];
+      bb1.mark();
+      bb2.mark();
+      bb1.get(array1);
+      bb2.get(array2);
+      bb1.reset();
+      bb2.reset();
+      return guava.compare(array1, array2);
+    };
+    verify(openClosedBackward(bb(7), bb(2)), comparator, 6, 4, 2);
+    verify(openClosedBackward(bb(8), bb(4)), comparator, 6, 4);
+  }
+
   @Test
   public void openClosedTest() {
     verify(openClosed(bb(3), bb(8)), 4, 6, 8);
