[BAEL-3392] Formatted code examples for [BAEL-3392]

libraries-2/src/test/java/com/baeldung/mapdb/TransactionsUnitTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.mapdb;
+
+import org.junit.Test;
+import org.mapdb.DB;
+import org.mapdb.DBMaker;
+import org.mapdb.Serializer;
+
+import java.util.NavigableSet;
+
+import static junit.framework.Assert.assertEquals;
+
+public class TransactionsUnitTest {
+
+    @Test
+    public void givenValidDBSetup_whenTransactionCommittedAndRolledBack_checkPreviousStateAchieved() {
+
+        DB db = DBMaker.memoryDB().transactionEnable().make();
+
+        NavigableSet<String> set = db
+          .treeSet("mySet")
+          .serializer(Serializer.STRING)
+          .createOrOpen();
+
+        set.add("One");
+        set.add("Two");
+
+        db.commit();
+
+        assertEquals(2, set.size());
+
+        set.add("Three");
+
+        assertEquals(3, set.size());
+
+        db.rollback();
+
+        assertEquals(2, set.size());
+
+        db.close();
+    }
+}