Handle transport start/stop failures

src/server.test.ts

@@ -186,4 +186,35 @@ describe('Server', () => {
 
     expect(transport.stop).toHaveBeenCalled();
   });
+
+  it('rolls back started transports if a later transport fails to start', async () => {
+    const server = new Server({ openrpcDocument: {} as any });
+
+    const first = createTestTransport();
+    const second = createTestTransport();
+    const error = new Error('boom');
+
+    first.start.mockResolvedValue(undefined);
+    second.start.mockRejectedValue(error);
+
+    (server as any).transports = [first, second];
+
+    await expect(server.start()).rejects.toThrow('boom');
+    expect(first.stop).toHaveBeenCalled();
+    expect(second.stop).not.toHaveBeenCalled();
+  });
+
+  it('continues stopping transports when one fails', async () => {
+    const server = new Server({ openrpcDocument: {} as any });
+
+    const first = createTestTransport();
+    const second = createTestTransport();
+    first.stop.mockRejectedValue(new Error('fail'));
+    second.stop.mockResolvedValue(undefined);
+
+    (server as any).transports = [first, second];
+
+    await expect(server.stop()).rejects.toThrow('fail');
+    expect(second.stop).toHaveBeenCalled();
+  });
 });

src/server.ts

@@ -72,14 +72,36 @@ export default class Server {
   }
 
   public async start() {
-    for (const transport of this.transports) {
-      await transport.start();
+    const started: typeof this.transports = [];
+    try {
+      for (const transport of this.transports) {
+        await transport.start();
+        started.push(transport);
+      }
+    } catch (e) {
+      for (const transport of started.reverse()) {
+        try {
+          await transport.stop();
+        } catch (_) {
+          // ignore rollback errors
+        }
+      }
+      throw e;
     }
   }
 
   public async stop() {
+    const errors: Error[] = [];
     for (const transport of this.transports) {
-      await transport.stop();
+      try {
+        await transport.stop();
+      } catch (err) {
+        errors.push(err as Error);
+      }
+    }
+    if (errors.length > 0) {
+      const message = errors.map((err) => err.message).join('; ');
+      throw new Error(`Failed to stop transports: ${message}`);
     }
   }