Check connection state before start stop and send (#2824)

clients/java/signalr/src/main/java/com/microsoft/aspnet/signalr/HubConnection.java

@@ -142,6 +142,10 @@ public class HubConnection {
      * @throws Exception An error occurred while connecting.
      */
     public void start() throws Exception {
+        if (connectionState != HubConnectionState.DISCONNECTED) {
+            return;
+        }
+
         logger.log(LogLevel.Debug, "Starting HubConnection");
         transport.setOnReceive(this.callback);
         transport.start();
@@ -155,7 +159,11 @@ public class HubConnection {
      * Stops a connection to the server.
      */
     private void stop(String errorMessage) {
-        if(errorMessage != null){
+        if (connectionState == HubConnectionState.DISCONNECTED) {
+            return;
+        }
+
+        if(errorMessage != null) {
             logger.log(LogLevel.Error , "HubConnection disconnected with an error %s.", errorMessage);
         } else {
             logger.log(LogLevel.Debug, "Stopping HubConnection.");
@@ -187,6 +195,10 @@ public class HubConnection {
      * @throws Exception If there was an error while sending.
      */
     public void send(String method, Object... args) throws Exception {
+        if (connectionState != HubConnectionState.CONNECTED) {
+            throw new HubException("The 'send' method cannot be called if the connection is not active");
+        }
+
         InvocationMessage invocationMessage = new InvocationMessage(method, args);
         String message = protocol.writeMessage(invocationMessage);
         logger.log(LogLevel.Debug, "Sending message");

clients/java/signalr/src/test/java/HubConnectionTest.java

@@ -4,7 +4,10 @@
 import com.microsoft.aspnet.signalr.*;
 import java.util.ArrayList;
 import java.util.concurrent.atomic.AtomicReference;
+
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 import static org.junit.Assert.*;
 
@@ -87,7 +90,6 @@ public class HubConnectionTest {
         assertEquals(1, value.get(), 0);
 
         hubConnection.remove("inc");
-        hubConnection.send("inc");
         assertEquals(1, value.get(), 0);
     }
 
@@ -656,6 +658,35 @@ public class HubConnectionTest {
 
         assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
     }
+    
+    @Test
+    public void CallingStartOnStartedHubConnectionNoOps() throws Exception {
+        Transport mockTransport = new MockTransport();
+        HubConnection hubConnection = new HubConnection("http://example.com", mockTransport);
+        hubConnection.start();
+        assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
+
+        hubConnection.start();
+        assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
+
+        hubConnection.stop();
+        assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
+    }
+
+    @Rule
+    public ExpectedException exceptionRule = ExpectedException.none();
+
+    @Test
+    public void CannotSendBeforeStart() throws Exception {
+        exceptionRule.expect(HubException.class);
+        exceptionRule.expectMessage("The 'send' method cannot be called if the connection is not active");
+
+        Transport mockTransport = new MockTransport();
+        HubConnection hubConnection = new HubConnection("http://example.com", mockTransport);
+        assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
+
+        hubConnection.send("inc");
+    }
 
     private class MockTransport implements Transport {
         private OnReceiveCallBack onReceiveCallBack;