Session#reset() releases connection last

Previously it tried to first release connection and then mark existing
transaction as terminated. This could've been problematic because it
allowed transaction to be used on the client after RESET, which clears
connection state on the server.

This commit makes `Session#reset()` first mark existing transaction as
terminated and only then release the connection. Releasing connection
implies RESET.

Author: lutovich

driver/src/main/java/org/neo4j/driver/internal/NetworkSession.java

@@ -254,14 +254,13 @@ public void reset()
 
     private CompletionStage<Void> resetAsync()
     {
-        return releaseConnectionNow().thenCompose( ignore -> existingTransactionOrNull() )
-                .thenAccept( tx ->
-                {
-                    if ( tx != null )
-                    {
-                        tx.markTerminated();
-                    }
-                } );
+        return existingTransactionOrNull().thenAccept( tx ->
+        {
+            if ( tx != null )
+            {
+                tx.markTerminated();
+            }
+        } ).thenCompose( ignore -> releaseConnectionNow() );
     }
 
     @Override

driver/src/test/java/org/neo4j/driver/internal/NetworkSessionTest.java

@@ -663,6 +663,25 @@ public void shouldBeginTxAfterRunFailureToAcquireConnection()
         verifyBeginTx( connection, times( 1 ) );
     }
 
+    @Test
+    public void shouldMarkTransactionAsTerminatedAndThenReleaseConnectionOnReset()
+    {
+        NetworkSession session = newSession( connectionProvider, READ );
+        Transaction tx = session.beginTransaction();
+
+        assertTrue( tx.isOpen() );
+        when( connection.releaseNow() ).then( invocation ->
+        {
+            // verify that tx is not open when connection is released
+            assertFalse( tx.isOpen() );
+            return completedFuture( null );
+        } );
+
+        session.reset();
+
+        verify( connection ).releaseNow();
+    }
+
     private void testConnectionAcquisition( AccessMode sessionMode, AccessMode transactionMode )
     {
         NetworkSession session = newSession( connectionProvider, sessionMode );