fix(core-backend): control randomness to fix flaky test

Author: Kriys94

packages/core-backend/src/BackendWebSocketService.test.ts

@@ -817,14 +817,17 @@ describe('BackendWebSocketService', () => {
     it('should skip connect when reconnect timer is already scheduled', async () => {
       await withService(
         async ({ service, getMockWebSocket, completeAsyncOperations }) => {
+          // Mock Math.random to make Cockatiel's jitter deterministic
+          jest.spyOn(Math, 'random').mockReturnValue(0);
+
           // Connect successfully first
           await service.connect();
 
           const mockWs = getMockWebSocket();
 
           // Simulate unexpected close to trigger scheduleReconnect
           mockWs.simulateClose(1006, 'Abnormal closure');
-          await completeAsyncOperations(10);
+          await completeAsyncOperations(0);
 
           // Verify reconnect timer is scheduled
           const attemptsBefore = service.getConnectionInfo().reconnectAttempts;
@@ -894,14 +897,22 @@ describe('BackendWebSocketService', () => {
       await withService(
         { mockWebSocketOptions: { autoConnect: false } },
         async ({ service, getMockWebSocket, completeAsyncOperations }) => {
+          // Mock Math.random to make Cockatiel's jitter deterministic
+          jest.spyOn(Math, 'random').mockReturnValue(0);
+
           // eslint-disable-next-line @typescript-eslint/no-floating-promises
           service.connect();
           await completeAsyncOperations(10);
 
-          // Close during connection phase
+          // Verify we're in CONNECTING state
           const mockWs = getMockWebSocket();
+          expect(service.getConnectionInfo().state).toBe(
+            WebSocketState.CONNECTING,
+          );
+
+          // Close during connection phase
           mockWs.simulateClose(1006, 'Connection failed');
-          await completeAsyncOperations(10);
+          await completeAsyncOperations(0);
 
           // Should schedule reconnect and be in ERROR state
           expect(service.getConnectionInfo().state).toBe(WebSocketState.ERROR);
@@ -916,6 +927,9 @@ describe('BackendWebSocketService', () => {
           mockWebSocketOptions: { autoConnect: false },
         },
         async ({ service, getMockWebSocket, completeAsyncOperations }) => {
+          // Mock Math.random to make Cockatiel's jitter deterministic
+          jest.spyOn(Math, 'random').mockReturnValue(0);
+
           // Start connection (this sets connectionTimeout)
           // eslint-disable-next-line @typescript-eslint/no-floating-promises
           service.connect();
@@ -939,7 +953,7 @@ describe('BackendWebSocketService', () => {
           // Since state is ERROR (not CONNECTING), onclose will call handleClose
           // which will clear connectionTimeout
           mockWs.simulateClose(1006, 'Close after timeout');
-          await completeAsyncOperations(10);
+          await completeAsyncOperations(0);
 
           // State should still be ERROR or DISCONNECTED
           expect([WebSocketState.ERROR, WebSocketState.DISCONNECTED]).toContain(
@@ -952,6 +966,9 @@ describe('BackendWebSocketService', () => {
     it('should not schedule multiple reconnects when scheduleReconnect called multiple times', async () => {
       await withService(
         async ({ service, getMockWebSocket, completeAsyncOperations }) => {
+          // Mock Math.random to make Cockatiel's jitter deterministic
+          jest.spyOn(Math, 'random').mockReturnValue(0);
+
           await service.connect();
           expect(service.getConnectionInfo().state).toBe(
             WebSocketState.CONNECTED,
@@ -961,15 +978,15 @@ describe('BackendWebSocketService', () => {
 
           // First close to trigger scheduleReconnect
           mockWs.simulateClose(1006, 'Connection lost');
-          await completeAsyncOperations(10);
+          await completeAsyncOperations(0);
 
           const attemptsBefore = service.getConnectionInfo().reconnectAttempts;
           expect(attemptsBefore).toBeGreaterThan(0);
 
           // Second close should trigger scheduleReconnect again,
           // but it should return early since timer already exists
           mockWs.simulateClose(1006, 'Connection lost again');
-          await completeAsyncOperations(10);
+          await completeAsyncOperations(0);
 
           // Attempts should not have increased again due to idempotency
           expect(service.getConnectionInfo().reconnectAttempts).toBe(
@@ -987,6 +1004,9 @@ describe('BackendWebSocketService', () => {
     it('should force reconnection and schedule connect', async () => {
       await withService(
         async ({ service, getMockWebSocket, completeAsyncOperations }) => {
+          // Mock Math.random to make Cockatiel's jitter deterministic
+          jest.spyOn(Math, 'random').mockReturnValue(0);
+
           await service.connect();
           expect(service.getConnectionInfo().state).toBe(
             WebSocketState.CONNECTED,
@@ -1001,7 +1021,7 @@ describe('BackendWebSocketService', () => {
 
           // Force reconnection
           await service.forceReconnection();
-          await completeAsyncOperations(10);
+          await completeAsyncOperations(0);
 
           // Should be disconnected after forceReconnection
           expect(service.getConnectionInfo().state).toBe(
@@ -1018,14 +1038,17 @@ describe('BackendWebSocketService', () => {
       await withService(
         { mockWebSocketOptions: { autoConnect: false } },
         async ({ service, getMockWebSocket, completeAsyncOperations }) => {
+          // Mock Math.random to make Cockatiel's jitter deterministic
+          jest.spyOn(Math, 'random').mockReturnValue(0);
+
           // Trigger a connection failure to schedule a reconnect
           // eslint-disable-next-line @typescript-eslint/no-floating-promises
           service.connect();
           await completeAsyncOperations(10);
 
           const mockWs = getMockWebSocket();
           mockWs.simulateError();
-          await completeAsyncOperations(10);
+          await completeAsyncOperations(0);
 
           const attemptsBefore = service.getConnectionInfo().reconnectAttempts;