Fix the failing test due to unreliable error type on different platforms

Author: Zhen

driver/src/main/java/org/neo4j/driver/internal/net/SocketClient.java

@@ -119,7 +119,10 @@ public void start()
         try
         {
             logger.debug( "~~ [CONNECT] %s", address );
-            setChannel( ChannelFactory.create( address, securityPlan, timeoutMillis, logger ) );
+            if( channel == null )
+            {
+                setChannel( ChannelFactory.create( address, securityPlan, timeoutMillis, logger ) );
+            }
             protocol = negotiateProtocol();
             reader = protocol.reader();
             writer = protocol.writer();

driver/src/test/java/org/neo4j/driver/internal/net/SocketClientTest.java

@@ -43,6 +43,7 @@
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.runners.Parameterized.Parameters;
+import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 import static org.neo4j.driver.internal.logging.DevNullLogger.DEV_NULL_LOGGER;
@@ -123,14 +124,20 @@ public void testConnectionTimeout() throws Throwable
     @Test
     public void testIOExceptionWhenFailedToEstablishConnection() throws Throwable
     {
-        BoltServerAddress address = new BoltServerAddress( "localhost", 0 ); // an illegal port
+        BoltServerAddress address = new BoltServerAddress( "localhost", 1234 ); // an random address
 
         SecurityPlan securityPlan = SecurityPlan.insecure();
         SocketClient client = new SocketClient( address, securityPlan, CONNECTION_TIMEOUT, DEV_NULL_LOGGER );
 
+        ByteChannel mockedChannel = mock( ByteChannel.class );
+        when( mockedChannel.write( any( ByteBuffer.class ) ) )
+                .thenThrow( new IOException( "Failed to connect to server due to IOException"
+        ) );
+        client.setChannel( mockedChannel );
+
         // Expect
         exception.expect( ServiceUnavailableException.class );
-        exception.expectMessage( "Unable to process request: Can't assign requested address" );
+        exception.expectMessage( "Unable to process request: Failed to connect to server due to IOException" );
 
         // When
         client.start();