[Java] Fix skip negotiate null ref (#30574)

Author: BrennanConroy

src/SignalR/build.cmd

@@ -1,3 +1,3 @@
 @ECHO OFF
 SET RepoRoot=%~dp0..\..
-%RepoRoot%\eng\build.cmd -buildJava -projects %~dp0**\*.*proj %*
+%RepoRoot%\eng\build.cmd -nobuildnative -buildJava -projects %~dp0**\*.*proj %*

src/SignalR/clients/java/signalr/core/src/main/java/com/microsoft/signalr/HttpHubConnectionBuilder.java

@@ -69,7 +69,8 @@ public HttpHubConnectionBuilder withHubProtocol(HubProtocol protocol) {
 
     /**
      * Indicates to the {@link HubConnection} that it should skip the negotiate process.
-     * Note: This option only works with the Websockets transport and the Azure SignalR Service require the negotiate step.
+     * Note: This option only works with the {@link TransportEnum#WEBSOCKETS} transport selected via {@link #withTransport(TransportEnum) withTransport},
+     * additionally the Azure SignalR Service requires the negotiate step so this will fail when using the Azure SignalR Service.
      *
      * @param skipNegotiate Boolean indicating if the {@link HubConnection} should skip the negotiate step.
      * @return This instance of the HttpHubConnectionBuilder.

src/SignalR/clients/java/signalr/core/src/main/java/com/microsoft/signalr/HubConnection.java

@@ -264,7 +264,16 @@ public Completable start() {
                 Transport transport = customTransport;
                 if (transport == null) {
                     Single<String> tokenProvider = negotiateResponse.getAccessToken() != null ? Single.just(negotiateResponse.getAccessToken()) : accessTokenProvider;
-                    switch (negotiateResponse.getChosenTransport()) {
+                    TransportEnum chosenTransport;
+                    if (this.skipNegotiate) {
+                        if (this.transportEnum != TransportEnum.WEBSOCKETS) {
+                            throw new RuntimeException("Negotiation can only be skipped when using the WebSocket transport directly with '.withTransport(TransportEnum.WEBSOCKETS)' on the 'HubConnectionBuilder'.");
+                        }
+                        chosenTransport = this.transportEnum;
+                    } else {
+                        chosenTransport = negotiateResponse.getChosenTransport();
+                    }
+                    switch (chosenTransport) {
                         case LONG_POLLING:
                             transport = new LongPollingTransport(localHeaders, httpClient, tokenProvider);
                             break;

src/SignalR/clients/java/signalr/test/src/main/java/com/microsoft/signalr/HubConnectionTest.java

@@ -2743,6 +2743,63 @@ public void noConnectionIdWhenSkippingNegotiate() {
         assertNull(hubConnection.getConnectionId());
     }
 
+    @Test
+    public void SkippingNegotiateDoesNotNegotiate() {
+        try (TestLogger logger = new TestLogger(WebSocketTransport.class.getName())) {
+            AtomicBoolean negotiateCalled = new AtomicBoolean(false);
+            TestHttpClient client = new TestHttpClient().on("POST", "http://example.com/negotiate?negotiateVersion=1",
+                    (req) -> {
+                        negotiateCalled.set(true);
+                        return Single.just(new HttpResponse(200, "",
+                            TestUtils.stringToByteBuffer("{\"connectionId\":\"bVOiRPG8-6YiJ6d7ZcTOVQ\",\""
+                                    + "availableTransports\":[{\"transport\":\"WebSockets\",\"transferFormats\":[\"Text\",\"Binary\"]}]}")));
+                    });
+
+            HubConnection hubConnection = HubConnectionBuilder
+                    .create("http://example")
+                    .withTransport(TransportEnum.WEBSOCKETS)
+                    .shouldSkipNegotiate(true)
+                    .withHttpClient(client)
+                    .build();
+
+            try {
+                hubConnection.start().timeout(30, TimeUnit.SECONDS).blockingAwait();
+            } catch (Exception e) {
+                assertEquals("WebSockets isn't supported in testing currently.", e.getMessage());
+            }
+            assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
+            assertFalse(negotiateCalled.get());
+
+            logger.assertLog("Starting Websocket connection.");
+        }
+    }
+
+    @Test
+    public void ThrowsIfSkipNegotiationSetAndTransportIsNotWebSockets() {
+        AtomicBoolean negotiateCalled = new AtomicBoolean(false);
+        TestHttpClient client = new TestHttpClient().on("POST", "http://example.com/negotiate?negotiateVersion=1",
+                (req) -> {
+                    negotiateCalled.set(true);
+                    return Single.just(new HttpResponse(200, "",
+                        TestUtils.stringToByteBuffer("{\"connectionId\":\"bVOiRPG8-6YiJ6d7ZcTOVQ\",\""
+                                + "availableTransports\":[{\"transport\":\"WebSockets\",\"transferFormats\":[\"Text\",\"Binary\"]}]}")));
+                });
+
+        HubConnection hubConnection = HubConnectionBuilder
+                .create("http://example")
+                .shouldSkipNegotiate(true)
+                .withHttpClient(client)
+                .build();
+
+        try {
+            hubConnection.start().timeout(30, TimeUnit.SECONDS).blockingAwait();
+        } catch (Exception e) {
+            assertEquals("Negotiation can only be skipped when using the WebSocket transport directly with '.withTransport(TransportEnum.WEBSOCKETS)' on the 'HubConnectionBuilder'.", e.getMessage());
+        }
+        assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
+        assertFalse(negotiateCalled.get());
+    }
+
     @Test
     public void connectionIdIsAvailableAfterStart() {
         TestHttpClient client = new TestHttpClient().on("POST", "http://example.com/negotiate?negotiateVersion=1",