Fixed couple flaky tests

Couple tests in `SessionAsyncIT` were flaky because they tried to run
queries after killing the database and only retrieval from result cursor
was expected to throw. However, `#runAsync()` itself can also throw
because connection can't be acquired. This commit makes code treat
exception from `#runAsync()` as expected.

Stress test queries can handle leader switches but still tried to assert
on number of created nodes even after failure. This commit makes them
skip assertion after a handled failure.

Author: lutovich

driver/src/test/java/org/neo4j/driver/v1/integration/SessionAsyncIT.java

@@ -659,10 +659,10 @@ public void shouldRunAfterRunFailureToAcquireConnection()
     {
         neo4j.killDb();
 
-        StatementResultCursor cursor1 = getBlocking( session.runAsync( "RETURN 42" ) );
         try
         {
-            getBlocking( cursor1.nextAsync() );
+            StatementResultCursor cursor = getBlocking( session.runAsync( "RETURN 42" ) );
+            getBlocking( cursor.nextAsync() );
             fail( "Exception expected" );
         }
         catch ( ServiceUnavailableException e )
@@ -705,10 +705,10 @@ public void shouldBeginTxAfterRunFailureToAcquireConnection()
     {
         neo4j.killDb();
 
-        StatementResultCursor cursor1 = await( session.runAsync( "RETURN 42" ) );
         try
         {
-            getBlocking( cursor1.consumeAsync() );
+            StatementResultCursor cursor = await( session.runAsync( "RETURN 42" ) );
+            getBlocking( cursor.consumeAsync() );
             fail( "Exception expected" );
         }
         catch ( ServiceUnavailableException e )

driver/src/test/java/org/neo4j/driver/v1/stress/AsyncWriteQuery.java

@@ -49,21 +49,25 @@ public CompletionStage<Void> execute( C context )
                 {
                     session.closeAsync();
 
-                    handleError( Futures.completionErrorCause( error ), context );
-                    assertEquals( 1, summary.counters().nodesCreated() );
-                    context.nodeCreated();
+                    if ( error != null )
+                    {
+                        handleError( Futures.completionErrorCause( error ), context );
+                    }
+                    else
+                    {
+                        assertEquals( 1, summary.counters().nodesCreated() );
+                        context.nodeCreated();
+                    }
+
                     return null;
                 } );
     }
 
     private void handleError( Throwable error, C context )
     {
-        if ( error != null )
+        if ( !stressTest.handleWriteFailure( error, context ) )
         {
-            if ( !stressTest.handleWriteFailure( error, context ) )
-            {
-                throw new RuntimeException( error );
-            }
+            throw new RuntimeException( error );
         }
     }
 }

driver/src/test/java/org/neo4j/driver/v1/stress/AsyncWriteQueryInTx.java

@@ -52,21 +52,25 @@ public CompletionStage<Void> execute( C context )
         {
             session.closeAsync();
 
-            handleError( Futures.completionErrorCause( error ), context );
-            assertEquals( 1, summary.counters().nodesCreated() );
-            context.nodeCreated();
+            if ( error != null )
+            {
+                handleError( Futures.completionErrorCause( error ), context );
+            }
+            else
+            {
+                assertEquals( 1, summary.counters().nodesCreated() );
+                context.nodeCreated();
+            }
+
             return null;
         } );
     }
 
     private void handleError( Throwable error, C context )
     {
-        if ( error != null )
+        if ( !stressTest.handleWriteFailure( error, context ) )
         {
-            if ( !stressTest.handleWriteFailure( error, context ) )
-            {
-                throw new RuntimeException( error );
-            }
+            throw new RuntimeException( error );
         }
     }
 }

driver/src/test/java/org/neo4j/driver/v1/stress/BlockingWriteQuery.java

@@ -39,20 +39,22 @@ public BlockingWriteQuery( AbstractStressTestBase<C> stressTest, Driver driver,
     public void execute( C context )
     {
         StatementResult result = null;
+        Throwable queryError = null;
 
         try ( Session session = newSession( AccessMode.WRITE, context ) )
         {
             result = session.run( "CREATE ()" );
         }
         catch ( Throwable error )
         {
+            queryError = error;
             if ( !stressTest.handleWriteFailure( error, context ) )
             {
                 throw error;
             }
         }
 
-        if ( result != null )
+        if ( queryError == null && result != null )
         {
             assertEquals( 1, result.summary().counters().nodesCreated() );
             context.nodeCreated();

driver/src/test/java/org/neo4j/driver/v1/stress/BlockingWriteQueryInTx.java

@@ -40,6 +40,7 @@ public BlockingWriteQueryInTx( AbstractStressTestBase<C> stressTest, Driver driv
     public void execute( C context )
     {
         StatementResult result = null;
+        Throwable txError = null;
 
         try ( Session session = newSession( AccessMode.WRITE, context ) )
         {
@@ -53,13 +54,14 @@ public void execute( C context )
         }
         catch ( Throwable error )
         {
+            txError = error;
             if ( !stressTest.handleWriteFailure( error, context ) )
             {
                 throw error;
             }
         }
 
-        if ( result != null )
+        if ( txError == null && result != null )
         {
             assertEquals( 1, result.summary().counters().nodesCreated() );
             context.nodeCreated();