feat: implement WebSocket client cache eviction on error

- Evict the cached WebSocket client when a WebSocket error occurs, ensuring that subsequent subscriptions create a fresh client.
- Add tests to verify the behavior of client cache eviction upon WebSocket errors, confirming that the client is recreated as expected.

This change enhances the reliability of WebSocket subscriptions by preventing stale connections.

Author: AgustinRamiroDiaz

src/subscriptions/actions.ts

@@ -114,6 +114,8 @@ function createEventStream<T>(
       resolveNext = null;
       rejectNext = null;
     }
+    // Evict the dead WebSocket client so the next subscription creates a fresh one
+    wsClientCache.delete(client);
     // Auto-terminate stream on WebSocket failure so subsequent next() calls
     // return {done: true} instead of hanging indefinitely
     isUnsubscribed = true;

tests/subscriptions.test.ts

@@ -7,11 +7,29 @@ import {
 } from "@/subscriptions/actions";
 import {GenLayerClient, GenLayerChain} from "@/types";
 
+// Track createPublicClient calls and captured onError handlers
+const {createPublicClientSpy, getCapturedOnError, setCapturedOnError} = vi.hoisted(() => {
+  let capturedOnError: ((error: Error) => void) | null = null;
+  return {
+    createPublicClientSpy: vi.fn(() => ({
+      watchContractEvent: vi.fn((opts: {onError?: (error: Error) => void}) => {
+        capturedOnError = opts.onError ?? null;
+        return vi.fn(); // unwatch function
+      }),
+    })),
+    getCapturedOnError: () => capturedOnError,
+    setCapturedOnError: (v: ((error: Error) => void) | null) => {
+      capturedOnError = v;
+    },
+  };
+});
+
 // Mock viem module for WebSocket-related tests
 vi.mock("viem", async importOriginal => {
   const actual = (await importOriginal()) as object;
   return {
     ...actual,
+    createPublicClient: createPublicClientSpy,
     webSocket: vi.fn(() => ({
       request: vi.fn(),
       type: "webSocket" as const,
@@ -189,3 +207,33 @@ describe("ConsensusEventStream interface", () => {
     expect(typeof actions.subscribeToTransactionLeaderTimeout).toBe("function");
   });
 });
+
+describe("WebSocket client cache eviction on error", () => {
+  afterEach(() => {
+    setCapturedOnError(null);
+    vi.restoreAllMocks();
+  });
+
+  it("should evict cached wsClient on WebSocket error so next subscription creates a fresh client", () => {
+    createPublicClientSpy.mockClear();
+    const client = createMockClient({webSocketUrl: "wss://example.com/ws"});
+    const actions = subscriptionActions(client);
+
+    // First subscription creates the wsClient
+    actions.subscribeToNewTransaction();
+    expect(createPublicClientSpy).toHaveBeenCalledTimes(1);
+
+    // Second subscription reuses the cached wsClient
+    actions.subscribeToNewTransaction();
+    expect(createPublicClientSpy).toHaveBeenCalledTimes(1);
+
+    // Simulate a WebSocket error
+    const onError = getCapturedOnError();
+    expect(onError).not.toBeNull();
+    onError!(new Error("WebSocket connection closed"));
+
+    // Third subscription should create a new wsClient because the cache was evicted
+    actions.subscribeToNewTransaction();
+    expect(createPublicClientSpy).toHaveBeenCalledTimes(2);
+  });
+});