[Java] Make public API look like RxJava (#3103)

.vscode/launch.json

@@ -8,7 +8,7 @@
             "cwd": "${workspaceFolder}/clients/java/",
             "console": "externalTerminal",
             "stopOnEntry": false,
-            "mainClass": "com.microsoft.aspnet.signalr.sample.Chat",
+            "mainClass": "com.microsoft.signalr.sample.Chat",
             "args": ""
         },
         {

clients/java/signalr/build.gradle

@@ -33,6 +33,7 @@ dependencies {
     testRuntime 'org.junit.jupiter:junit-jupiter-engine:5.3.1'
     implementation 'com.google.code.gson:gson:2.8.5'
     implementation 'com.squareup.okhttp3:okhttp:3.11.0'
+    implementation 'io.reactivex.rxjava2:rxjava:2.2.2'
 }
 
 spotless {

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

@@ -6,13 +6,15 @@ package com.microsoft.signalr;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Supplier;
 
+import io.reactivex.Single;
+
 public class HttpHubConnectionBuilder {
     private String url;
     private Transport transport;
     private Logger logger;
     private HttpClient httpClient;
     private boolean skipNegotiate;
-    private Supplier<CompletableFuture<String>> accessTokenProvider;
+    private Single<String> accessTokenProvider;
 
     HttpHubConnectionBuilder(String url) {
         this.url = url;
@@ -39,7 +41,7 @@ public class HttpHubConnectionBuilder {
         return this;
     }
 
-    public HttpHubConnectionBuilder withAccessTokenProvider(Supplier<CompletableFuture<String>> accessTokenProvider) {
+    public HttpHubConnectionBuilder withAccessTokenProvider(Single<String> accessTokenProvider) {
         this.accessTokenProvider = accessTokenProvider;
         return this;
     }

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

@@ -9,12 +9,13 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.ExecutionException;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
-import java.util.function.Supplier;
+
+import io.reactivex.Completable;
+import io.reactivex.Single;
 
 public class HubConnection {
     private static final String RECORD_SEPARATOR = "\u001e";
@@ -32,13 +33,13 @@ public class HubConnection {
     private Logger logger;
     private List<Consumer<Exception>> onClosedCallbackList;
     private boolean skipNegotiate;
-    private Supplier<CompletableFuture<String>> accessTokenProvider;
+    private Single<String> accessTokenProvider;
     private Map<String, String> headers = new HashMap<>();
     private ConnectionState connectionState = null;
     private HttpClient httpClient;
     private String stopError;
 
-    HubConnection(String url, Transport transport, boolean skipNegotiate, Logger logger, HttpClient httpClient, Supplier<CompletableFuture<String>> accessTokenProvider) {
+    HubConnection(String url, Transport transport, boolean skipNegotiate, Logger logger, HttpClient httpClient, Single<String> accessTokenProvider) {
         if (url == null || url.isEmpty()) {
             throw new IllegalArgumentException("A valid url is required.");
         }
@@ -49,7 +50,7 @@ public class HubConnection {
         if (accessTokenProvider != null) {
             this.accessTokenProvider = accessTokenProvider;
         } else {
-            this.accessTokenProvider = () -> CompletableFuture.completedFuture(null);
+            this.accessTokenProvider = Single.just("");
         }
 
         if (httpClient != null) {
@@ -153,14 +154,11 @@ public class HubConnection {
             }
 
             if (negotiateResponse.getAccessToken() != null) {
-                this.accessTokenProvider = () -> CompletableFuture.completedFuture(negotiateResponse.getAccessToken());
+                this.accessTokenProvider = Single.just(negotiateResponse.getAccessToken());
                 String token = "";
-                try {
+                // We know the Single is non blocking in this case
-                    // We know the future is already completed in this case
+                // It's fine to call blockingGet() on it.
-                    // It's fine to call get() on it.
+                token = this.accessTokenProvider.blockingGet();
-                    token = this.accessTokenProvider.get().get();
-                } catch (InterruptedException | ExecutionException e) {
-                }
                 this.headers.put("Authorization", "Bearer " + token);
             }
 
@@ -179,20 +177,21 @@ public class HubConnection {
 
     /**
      * Starts a connection to the server.
-     * @return A completable future that completes when the connection has been established.
+     * @return A Completable that completes when the connection has been established.
      */
-    public CompletableFuture<Void> start() {
+    public Completable start() {
         if (hubConnectionState != HubConnectionState.DISCONNECTED) {
-            return CompletableFuture.completedFuture(null);
+            return Completable.complete();
         }
 
         handshakeReceived = false;
-        CompletableFuture<Void> tokenFuture = accessTokenProvider.get()
+        CompletableFuture<Void> tokenFuture = new CompletableFuture<>(); 
-                .thenAccept((token) -> {
+        accessTokenProvider.subscribe(token -> {
-                    if (token != null) {
+            if (token != null && !token.isEmpty()) {
-                        this.headers.put("Authorization", "Bearer " + token);
+                this.headers.put("Authorization", "Bearer " + token);
-                    }
+            }
-                });
+            tokenFuture.complete(null);
+        });
 
         stopError = null;
         CompletableFuture<String> negotiate = null;
@@ -202,7 +201,7 @@ public class HubConnection {
             negotiate = tokenFuture.thenCompose((v) -> CompletableFuture.completedFuture(baseUrl));
         }
 
-        return negotiate.thenCompose((url) -> {
+        return Completable.fromFuture(negotiate.thenCompose(url -> {
             logger.log(LogLevel.Debug, "Starting HubConnection.");
             if (transport == null) {
                 transport = new WebSocketTransport(headers, httpClient, logger);
@@ -211,27 +210,21 @@ public class HubConnection {
             transport.setOnReceive(this.callback);
             transport.setOnClose((message) -> stopConnection(message));
 
-            try {
+            return transport.start(url).thenCompose((future) -> {
-                return transport.start(url).thenCompose((future) -> {
+                String handshake = HandshakeProtocol.createHandshakeRequestMessage(
-                    String handshake = HandshakeProtocol.createHandshakeRequestMessage(
+                        new HandshakeRequestMessage(protocol.getName(), protocol.getVersion()));
-                            new HandshakeRequestMessage(protocol.getName(), protocol.getVersion()));
+                return transport.send(handshake).thenRun(() -> {
-                    return transport.send(handshake).thenRun(() -> {
+                    hubConnectionStateLock.lock();
-                        hubConnectionStateLock.lock();
+                    try {
-                        try {
+                        hubConnectionState = HubConnectionState.CONNECTED;
-                            hubConnectionState = HubConnectionState.CONNECTED;
+                        connectionState = new ConnectionState(this);
-                            connectionState = new ConnectionState(this);
+                        logger.log(LogLevel.Information, "HubConnection started.");
-                            logger.log(LogLevel.Information, "HubConnection started.");
+                    } finally {
-                        } finally {
+                        hubConnectionStateLock.unlock();
-                            hubConnectionStateLock.unlock();
+                    }
-                        }
-                    });
                 });
-            } catch (RuntimeException e) {
+            });
-                throw e;
+        }));
-            } catch (Exception e) {
-                throw new RuntimeException(e);
-            }
-        });
     }
 
     private CompletableFuture<String> startNegotiate(String url, int negotiateAttempts) {
@@ -268,7 +261,7 @@ public class HubConnection {
     /**
      * Stops a connection to the server.
      * @param errorMessage An error message if the connected needs to be stopped because of an error.
-     * @return A completable future that completes when the connection has been stopped.
+     * @return A Completable that completes when the connection has been stopped.
      */
     private CompletableFuture<Void> stop(String errorMessage) {
         hubConnectionStateLock.lock();
@@ -292,10 +285,10 @@ public class HubConnection {
 
     /**
      * Stops a connection to the server.
-     * @return A completable future that completes when the connection has been stopped.
+     * @return A Completable that completes when the connection has been stopped.
      */
-    public CompletableFuture<Void> stop() {
+    public Completable stop() {
-        return stop(null);
+        return Completable.fromFuture(stop(null));
     }
 
     private void stopConnection(String errorMessage) {
@@ -344,7 +337,7 @@ public class HubConnection {
         sendHubMessage(invocationMessage);
     }
 
-    public <T> CompletableFuture<T> invoke(Class<T> returnType, String method, Object... args) throws Exception {
+    public <T> Single<T> invoke(Class<T> returnType, String method, Object... args) throws Exception {
         String id = connectionState.getNextInvocationId();
         InvocationMessage invocationMessage = new InvocationMessage(id, method, args);
 
@@ -372,7 +365,7 @@ public class HubConnection {
         // where the map doesn't have the future yet when the response is returned
         sendHubMessage(invocationMessage);
 
-        return future;
+        return Single.fromFuture(future);
     }
 
     private void sendHubMessage(HubMessage message) throws Exception {

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

@@ -11,10 +11,13 @@ import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.junit.jupiter.api.Test;
 
+import io.reactivex.Completable;
+import io.reactivex.Single;
 
 class HubConnectionTest {
     private static final String RECORD_SEPARATOR = "\u001e";
@@ -22,7 +25,7 @@ class HubConnectionTest {
     @Test
     public void checkHubConnectionState() throws Exception {
         HubConnection hubConnection = TestUtils.createHubConnection("http://example.com");
-        hubConnection.start();
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
 
         hubConnection.stop();
@@ -33,7 +36,7 @@ class HubConnectionTest {
     public void transportCloseTriggersStopInHubConnection() throws Exception {
         MockTransport mockTransport = new MockTransport();
         HubConnection hubConnection = TestUtils.createHubConnection("http://example.com", mockTransport);
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
         mockTransport.stop();
 
@@ -51,7 +54,7 @@ class HubConnectionTest {
             message.set(error.getMessage());
         });
 
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
         mockTransport.stopWithError(errorMessage);
         assertEquals(errorMessage, message.get());
@@ -355,13 +358,15 @@ class HubConnectionTest {
         hubConnection.start();
         mockTransport.receiveMessage("{}" + RECORD_SEPARATOR);
 
-        CompletableFuture<Integer> result = hubConnection.invoke(Integer.class, "echo", "message");
+        AtomicBoolean done = new AtomicBoolean();
+        Single<Integer> result = hubConnection.invoke(Integer.class, "echo", "message");
+        result.doOnSuccess(value -> done.set(true));
         assertEquals("{\"type\":1,\"invocationId\":\"1\",\"target\":\"echo\",\"arguments\":[\"message\"]}" + RECORD_SEPARATOR, mockTransport.getSentMessages()[1]);
-        assertFalse(result.isDone());
+        assertFalse(done.get());
 
         mockTransport.receiveMessage("{\"type\":3,\"invocationId\":\"1\",\"result\":42}" + RECORD_SEPARATOR);
 
-        assertEquals(Integer.valueOf(42), result.get(1000L, TimeUnit.MILLISECONDS));
+        assertEquals(Integer.valueOf(42), result.timeout(1000, TimeUnit.MILLISECONDS).blockingGet());
     }
 
     @Test
@@ -372,19 +377,23 @@ class HubConnectionTest {
         hubConnection.start();
         mockTransport.receiveMessage("{}" + RECORD_SEPARATOR);
 
-        CompletableFuture<Integer> result = hubConnection.invoke(Integer.class, "echo", "message");
+        AtomicBoolean doneFirst = new AtomicBoolean();
-        CompletableFuture<String> result2 = hubConnection.invoke(String.class, "echo", "message");
+        AtomicBoolean doneSecond = new AtomicBoolean();
+        Single<Integer> result = hubConnection.invoke(Integer.class, "echo", "message");
+        Single<String> result2 = hubConnection.invoke(String.class, "echo", "message");
+        result.doOnSuccess(value -> doneFirst.set(true));
+        result2.doOnSuccess(value -> doneSecond.set(true));
         assertEquals("{\"type\":1,\"invocationId\":\"1\",\"target\":\"echo\",\"arguments\":[\"message\"]}" + RECORD_SEPARATOR, mockTransport.getSentMessages()[1]);
         assertEquals("{\"type\":1,\"invocationId\":\"2\",\"target\":\"echo\",\"arguments\":[\"message\"]}" + RECORD_SEPARATOR, mockTransport.getSentMessages()[2]);
-        assertFalse(result.isDone());
+        assertFalse(doneFirst.get());
-        assertFalse(result2.isDone());
+        assertFalse(doneSecond.get());
 
         mockTransport.receiveMessage("{\"type\":3,\"invocationId\":\"2\",\"result\":\"message\"}" + RECORD_SEPARATOR);
-        assertEquals("message", result2.get(1000L, TimeUnit.MILLISECONDS));
+        assertEquals("message", result2.timeout(1000, TimeUnit.MILLISECONDS).blockingGet());
-        assertFalse(result.isDone());
+        assertFalse(doneFirst.get());
 
         mockTransport.receiveMessage("{\"type\":3,\"invocationId\":\"1\",\"result\":42}" + RECORD_SEPARATOR);
-        assertEquals(Integer.valueOf(42), result.get(1000L, TimeUnit.MILLISECONDS));
+        assertEquals(Integer.valueOf(42), result.timeout(1000, TimeUnit.MILLISECONDS).blockingGet());
     }
 
     @Test
@@ -395,14 +404,16 @@ class HubConnectionTest {
         hubConnection.start();
         mockTransport.receiveMessage("{}" + RECORD_SEPARATOR);
 
+        AtomicBoolean done = new AtomicBoolean();
         // int.class is a primitive type and since we use Class.cast to cast an Object to the expected return type
         // which does not work for primitives we have to write special logic for that case.
-        CompletableFuture<Integer> result = hubConnection.invoke(int.class, "echo", "message");
+        Single<Integer> result = hubConnection.invoke(int.class, "echo", "message");
-        assertFalse(result.isDone());
+        result.doOnSuccess(value -> done.set(true));
+        assertFalse(done.get());
 
         mockTransport.receiveMessage("{\"type\":3,\"invocationId\":\"1\",\"result\":42}" + RECORD_SEPARATOR);
 
-        assertEquals(Integer.valueOf(42), result.get(1000L, TimeUnit.MILLISECONDS));
+        assertEquals(Integer.valueOf(42), result.timeout(1000, TimeUnit.MILLISECONDS).blockingGet());
     }
 
     @Test
@@ -413,17 +424,19 @@ class HubConnectionTest {
         hubConnection.start();
         mockTransport.receiveMessage("{}" + RECORD_SEPARATOR);
 
-        CompletableFuture<Integer> result = hubConnection.invoke(int.class, "echo", "message");
+        AtomicBoolean done = new AtomicBoolean();
-        assertFalse(result.isDone());
+        Single<Integer> result = hubConnection.invoke(int.class, "echo", "message");
+        result.doOnSuccess(value -> done.set(true));
+        assertFalse(done.get());
 
         mockTransport.receiveMessage("{\"type\":3,\"invocationId\":\"1\",\"error\":\"There was an error\"}" + RECORD_SEPARATOR);
 
         String exceptionMessage = null;
         try {
-            result.get(1000L, TimeUnit.MILLISECONDS);
+            result.timeout(1000, TimeUnit.MILLISECONDS).blockingGet();
             assertFalse(true);
         } catch (Exception ex) {
-            exceptionMessage = ex.getMessage();
+            exceptionMessage = ex.getCause().getMessage();
         }
 
         assertEquals("com.microsoft.signalr.HubException: There was an error", exceptionMessage);
@@ -437,14 +450,16 @@ class HubConnectionTest {
         hubConnection.start();
         mockTransport.receiveMessage("{}" + RECORD_SEPARATOR);
 
-        CompletableFuture<Integer> result = hubConnection.invoke(int.class, "echo", "message");
+        AtomicBoolean done = new AtomicBoolean();
-        assertFalse(result.isDone());
+        Single<Integer> result = hubConnection.invoke(int.class, "echo", "message");
+        result.doOnSuccess(value -> done.set(true));
+        assertFalse(done.get());
 
         hubConnection.stop();
 
         boolean hasException = false;
         try {
-            result.get(1000L, TimeUnit.MILLISECONDS);
+            result.timeout(1000, TimeUnit.MILLISECONDS).blockingGet();
             assertFalse(true);
         } catch (CancellationException ex) {
             hasException = true;
@@ -894,10 +909,10 @@ class HubConnectionTest {
             assertTrue(false);
         }, String.class);
 
-        CompletableFuture<Void> startFuture = hubConnection.start();
+        Completable startFuture = hubConnection.start();
         mockTransport.receiveMessage("{}" + RECORD_SEPARATOR);
 
-        startFuture.get(1000, TimeUnit.MILLISECONDS);
+        startFuture.blockingAwait(1000, TimeUnit.MILLISECONDS);
         RuntimeException exception = assertThrows(RuntimeException.class, () -> mockTransport.receiveMessage("{\"type\":1,\"target\":\"Send\",\"arguments\":[]}" + RECORD_SEPARATOR));
         assertEquals("Invocation provides 0 argument(s) but target expects 1.", exception.getMessage());
     }
@@ -913,7 +928,7 @@ class HubConnectionTest {
                 .build();
 
         try {
-            hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+            hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         } catch(Exception ex) {}
 
         List<HttpRequest> sentRequests = client.getSentRequests();
@@ -931,8 +946,9 @@ class HubConnectionTest {
             .withHttpClient(client)
             .build();
 
-        ExecutionException exception = assertThrows(ExecutionException.class, () -> hubConnection.start().get(1000, TimeUnit.MILLISECONDS));
+        RuntimeException exception = assertThrows(RuntimeException.class,
-        assertEquals("Negotiate redirection limit exceeded.", exception.getCause().getMessage());
+            () -> hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS));
+        assertEquals("Negotiate redirection limit exceeded.", exception.getCause().getCause().getMessage());
     }
 
     @Test
@@ -949,7 +965,7 @@ class HubConnectionTest {
                 .withHttpClient(client)
                 .build();
 
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
 
         String[] sentMessages = transport.getSentMessages();
         assertEquals(1, sentMessages.length);
@@ -968,8 +984,9 @@ class HubConnectionTest {
                 .withTransport(transport)
                 .build();
 
-        ExecutionException exception = assertThrows(ExecutionException.class, () -> hubConnection.start().get(1000, TimeUnit.MILLISECONDS));
+        RuntimeException exception = assertThrows(RuntimeException.class,
-        assertEquals("Test error.", exception.getCause().getMessage());
+            () -> hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS));
+        assertEquals("Test error.", exception.getCause().getCause().getMessage());
     }
 
     @Test
@@ -987,7 +1004,7 @@ class HubConnectionTest {
                 .withHttpClient(client)
                 .build();
 
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
         hubConnection.stop();
     }
@@ -1010,10 +1027,10 @@ class HubConnectionTest {
                 .create("http://example.com")
                 .withTransport(transport)
                 .withHttpClient(client)
-                .withAccessTokenProvider(() -> CompletableFuture.completedFuture("secretToken"))
+                .withAccessTokenProvider(Single.just("secretToken"))
                 .build();
 
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
         hubConnection.stop();
         assertEquals("Bearer secretToken", token.get());
@@ -1036,10 +1053,10 @@ class HubConnectionTest {
                 .create("http://example.com")
                 .withTransport(transport)
                 .withHttpClient(client)
-                .withAccessTokenProvider(() -> CompletableFuture.completedFuture("secretToken"))
+                .withAccessTokenProvider(Single.just("secretToken"))
                 .build();
 
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
         assertEquals("http://testexample.com/?id=bVOiRPG8-6YiJ6d7ZcTOVQ", transport.getUrl());
         hubConnection.stop();
@@ -1055,13 +1072,13 @@ class HubConnectionTest {
                 .shouldSkipNegotiate(true)
                 .build();
 
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
-        hubConnection.stop().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.stop().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
-        hubConnection.stop().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.stop().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
     }
 
@@ -1081,13 +1098,13 @@ class HubConnectionTest {
                 .withHttpClient(client)
                 .build();
 
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
-        hubConnection.stop().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.stop().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
-        hubConnection.start().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
-        hubConnection.stop().get(1000, TimeUnit.MILLISECONDS);
+        hubConnection.stop().blockingAwait(1000, TimeUnit.MILLISECONDS);
         assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
     }
 
@@ -1105,7 +1122,8 @@ class HubConnectionTest {
                 .withHttpClient(client)
                 .build();
 
-        ExecutionException exception = assertThrows(ExecutionException.class, () -> hubConnection.start().get(1000, TimeUnit.MILLISECONDS));
+        RuntimeException exception = assertThrows(RuntimeException.class,
-        assertEquals("Unexpected status code returned from negotiate: 500 Internal server error.", exception.getCause().getMessage());
+            () -> hubConnection.start().blockingAwait(1000, TimeUnit.MILLISECONDS));
+        assertEquals("Unexpected status code returned from negotiate: 500 Internal server error.", exception.getCause().getCause().getMessage());
     }
 }

clients/java/signalr/src/test/java/com/microsoft/signalr/sample/Chat.java

@@ -32,7 +32,7 @@ public class Chat {
         });
 
         //This is a blocking call
-        hubConnection.start().get();
+        hubConnection.start().blockingAwait();
 
         String message = "";
         while (!message.equals("leave")) {