test(metrics): pin DogStatsD error completion

Error callbacks and synchronous send failures must settle without falling through to the flush timeout.

Author: BridgeAR

src/metrics/dogstatsd.spec.ts

@@ -161,37 +161,47 @@ describe("LambdaDogStatsD", () => {
   });
 
   it("logs callback errors and completes the send", async () => {
+    jest.useFakeTimers();
     const error = new Error("callback failure");
-    mockSend.mockImplementation((_message, _port, _host, callback) => callback(error));
+    const callbacks = useControlledSocket();
     const client = new LambdaDogStatsD();
 
     client.distribution("metric", 1);
 
-    await expect(client.flush()).resolves.toBeUndefined();
+    const flush = client.flush();
+    callbacks[0](error);
+    expect(jest.getTimerCount()).toBe(0);
+    await expect(flush).resolves.toBeUndefined();
     expect(logDebug).toHaveBeenCalledWith("Unable to send metric packet: callback failure");
   });
 
   it("logs synchronous socket errors without throwing", async () => {
+    jest.useFakeTimers();
     mockSend.mockImplementation(() => {
       throw new Error("synchronous failure");
     });
     const client = new LambdaDogStatsD();
 
     client.distribution("metric", 1);
 
-    await expect(client.flush()).resolves.toBeUndefined();
+    const flush = client.flush();
+    expect(jest.getTimerCount()).toBe(0);
+    await expect(flush).resolves.toBeUndefined();
     expect(logDebug).toHaveBeenCalledWith("Unable to send metric packet: synchronous failure");
   });
 
   it("normalizes non-Error values thrown synchronously by the socket", async () => {
+    jest.useFakeTimers();
     mockSend.mockImplementation(() => {
       throw "non-error failure";
     });
     const client = new LambdaDogStatsD();
 
     client.distribution("metric", 1);
 
-    await expect(client.flush()).resolves.toBeUndefined();
+    const flush = client.flush();
+    expect(jest.getTimerCount()).toBe(0);
+    await expect(flush).resolves.toBeUndefined();
     expect(logDebug).toHaveBeenCalledWith("Unable to send metric packet: Unknown socket send failure");
   });