Reject StreamingTranscriber.connect on early socket failure

src/services/streaming/service.ts

@@ -414,11 +414,13 @@ export class StreamingTranscriber {
   }
 
   connect() {
-    return new Promise<BeginEvent>((resolve) => {
+    return new Promise<BeginEvent>((resolve, reject) => {
       if (this.socket) {
         throw new Error("Already connected");
       }
 
+      let hasBegun = false;
+
       const url = this.connectionUrl();
 
       if (this.token) {
@@ -454,11 +456,21 @@ Learn more at https://github.com/AssemblyAI/assemblyai-node-sdk/blob/main/docs/c
           this.flushTimer = undefined;
         }
         this.listeners.close?.(code, reason);
+        if (!hasBegun) {
+          reject(
+            new StreamingError(
+              reason || `Streaming connection closed before session began`,
+            ),
+          );
+        }
       };
 
       this.socket.onerror = (event: ErrorEvent) => {
-        if (event.error) this.listeners.error?.(event.error as Error);
-        else this.listeners.error?.(new Error(event.message));
+        const error = event.error
+          ? (event.error as Error)
+          : new Error(event.message);
+        this.listeners.error?.(error);
+        if (!hasBegun) reject(error);
       };
 
       this.socket.onmessage = ({ data }: MessageEvent) => {
@@ -471,11 +483,13 @@ Learn more at https://github.com/AssemblyAI/assemblyai-node-sdk/blob/main/docs/c
               message.error_code;
           }
           this.listeners.error?.(err);
+          if (!hasBegun) reject(err);
           return;
         }
 
         switch (message.type) {
           case "Begin": {
+            hasBegun = true;
             resolve(message);
             this.listeners.open?.(message);
             break;

tests/unit/streaming.test.ts

@@ -24,6 +24,15 @@ let aai: AssemblyAI;
 let rt: StreamingTranscriber;
 let onOpen: jest.Mock;
 
+function createDefaultTranscriber() {
+  return aai.streaming.transcriber({
+    websocketBaseUrl: websocketBaseUrl,
+    apiKey: "123",
+    sampleRate: 16_000,
+    speechModel: "universal-streaming-english",
+  });
+}
+
 async function connect(rt: StreamingTranscriber, server: WS) {
   const connectPromise = rt.connect();
   await server.connected;
@@ -42,12 +51,7 @@ describe("streaming", () => {
   beforeEach(async () => {
     server = new WS(websocketBaseUrl);
     aai = createClient();
-    rt = aai.streaming.transcriber({
-      websocketBaseUrl: websocketBaseUrl,
-      apiKey: "123",
-      sampleRate: 16_000,
-      speechModel: "universal-streaming-english",
-    });
+    rt = createDefaultTranscriber();
     onOpen = jest.fn();
     rt.on("open", onOpen);
     await connect(rt, server);
@@ -61,6 +65,54 @@ describe("streaming", () => {
 
   it("noop", async () => {});
 
+  it("rejects connect when the socket errors before Begin", async () => {
+    await cleanup();
+    WS.clean();
+
+    server = new WS(websocketBaseUrl);
+    rt = createDefaultTranscriber();
+    const connectPromise = rt.connect();
+    await server.connected;
+
+    server.error({
+      code: 0,
+      reason: "DNS failure",
+      wasClean: false,
+    });
+
+    await expect(connectPromise).rejects.toThrow(Error);
+
+    WS.clean();
+    server = new WS(websocketBaseUrl);
+    rt = createDefaultTranscriber();
+    await connect(rt, server);
+  });
+
+  it("rejects connect when the socket closes before Begin", async () => {
+    await cleanup();
+    WS.clean();
+
+    server = new WS(websocketBaseUrl);
+    rt = createDefaultTranscriber();
+    const connectPromise = rt.connect();
+    await server.connected;
+
+    server.close({
+      code: 4001,
+      reason: "upstream closed before Begin",
+      wasClean: false,
+    });
+
+    await expect(connectPromise).rejects.toThrow(
+      "upstream closed before Begin",
+    );
+
+    WS.clean();
+    server = new WS(websocketBaseUrl);
+    rt = createDefaultTranscriber();
+    await connect(rt, server);
+  });
+
   it("should include speaker_labels in connection URL", async () => {
     await cleanup();
     WS.clean();