add test for updating a value

block-storage/src/test/java/org/lucares/pdb/map/PersistentMapTest.java

@@ -4,10 +4,12 @@ import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.security.SecureRandom;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Queue;
@@ -57,6 +59,26 @@ public class PersistentMapTest {
         }
     }
 
+    @Test
+    public void testUpdateValues() throws Exception {
+        final Path file = dataDirectory.resolve("map.db");
+        try (final PersistentMap<String, String> map = new PersistentMap<>(file, dataDirectory,
+                PersistentMap.STRING_CODER, PersistentMap.STRING_CODER)) {
+            map.putValue("key", "first");
+
+            Assertions.assertEquals("first", map.getValue("key"));
+
+            map.putValue("key", "second");
+            Assertions.assertEquals("second", map.getValue("key"));
+
+            final List<String> allValuesInMap = new ArrayList<>();
+            map.forAll((k, v) -> {
+                allValuesInMap.add(v);
+            });
+            Assertions.assertEquals(List.of("second"), allValuesInMap);
+        }
+    }
+
     @Test
     public void testManyValues() throws Exception {
         final Path file = dataDirectory.resolve("map.db");