From 5ae04b09d2354ffdf96fd06e83f8b32639d427ae Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Tue, 9 Jun 2026 07:10:23 +0000
Subject: [PATCH] test: Add test coverage for utils/metrics.ts

Adds a comprehensive test suite for the Prometheus metrics definitions in src/utils/metrics.ts.
- Verifies that the registry is correctly initialized.
- Validates that all Job, Agent, Message, and System metrics are instantiated as the expected Prometheus classes (Counter, Gauge, Histogram).
- Includes a test to ensure the `uptimeSeconds` legacy alias updates correctly over time.

Co-authored-by: anusornc <11565019+anusornc@users.noreply.github.com>
---
 test/metrics.test.ts | 97 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 test/metrics.test.ts

diff --git a/test/metrics.test.ts b/test/metrics.test.ts
new file mode 100644
index 0000000..0e9f74f
--- /dev/null
+++ b/test/metrics.test.ts
@@ -0,0 +1,97 @@
+import { describe, it, expect, vi, afterEach, beforeEach } from 'vitest';
+import { Registry, Counter, Gauge, Histogram } from 'prom-client';
+import {
+  register,
+  jobsSubmitted,
+  jobsClaimed,
+  jobsCompleted,
+  jobsFailed,
+  jobsCancelled,
+  pendingJobs,
+  claimedJobs,
+  inProgressJobs,
+  jobDuration,
+  activeAgents,
+  agentsRegistered,
+  agentHeartbeats,
+  staleAgents,
+  wsConnections,
+  messagesTotal,
+  messageSize,
+  requestsTotal,
+  requestDuration,
+  errorsTotal,
+  rateLimited,
+  connectedAgents,
+  uptimeSeconds
+} from '../src/utils/metrics.js';
+
+describe('Metrics', () => {
+  it('should export a Registry instance', () => {
+    expect(register).toBeInstanceOf(Registry);
+  });
+
+  it('should correctly initialize Job Metrics', async () => {
+    expect(jobsSubmitted).toBeInstanceOf(Counter);
+    expect((await jobsSubmitted.get()).name).toBe('dap_jobs_submitted_total');
+
+    expect(jobsClaimed).toBeInstanceOf(Counter);
+    expect(jobsCompleted).toBeInstanceOf(Counter);
+    expect(jobsFailed).toBeInstanceOf(Counter);
+    expect(jobsCancelled).toBeInstanceOf(Counter);
+
+    expect(pendingJobs).toBeInstanceOf(Gauge);
+    expect(claimedJobs).toBeInstanceOf(Gauge);
+    expect(inProgressJobs).toBeInstanceOf(Gauge);
+
+    expect(jobDuration).toBeInstanceOf(Histogram);
+  });
+
+  it('should correctly initialize Agent Metrics', () => {
+    expect(activeAgents).toBeInstanceOf(Gauge);
+    expect(agentsRegistered).toBeInstanceOf(Counter);
+    expect(agentHeartbeats).toBeInstanceOf(Counter);
+    expect(staleAgents).toBeInstanceOf(Gauge);
+    expect(wsConnections).toBeInstanceOf(Gauge);
+  });
+
+  it('should correctly initialize Message Metrics', () => {
+    expect(messagesTotal).toBeInstanceOf(Counter);
+    expect(messageSize).toBeInstanceOf(Histogram);
+  });
+
+  it('should correctly initialize System Metrics', () => {
+    expect(requestsTotal).toBeInstanceOf(Counter);
+    expect(requestDuration).toBeInstanceOf(Histogram);
+    expect(errorsTotal).toBeInstanceOf(Counter);
+    expect(rateLimited).toBeInstanceOf(Counter);
+  });
+
+  it('should correctly initialize Legacy Metric Aliases', () => {
+    expect(connectedAgents).toBeInstanceOf(Gauge);
+    expect(uptimeSeconds).toBeInstanceOf(Gauge);
+  });
+
+  describe('uptimeSeconds update interval', () => {
+    beforeEach(() => {
+      // Don't use system time as it will mess with node's Date.now() inside the metrics.ts interval
+      // which has already been initialized before this test block.
+    });
+
+    afterEach(() => {
+      vi.useRealTimers();
+    });
+
+    it('should update uptimeSeconds periodically', async () => {
+      // Wait real time instead of fake timers since the module has already set its interval
+      // using the real `setInterval` when imported at the top of the file.
+      const initialValue = (await uptimeSeconds.get()).values[0].value;
+
+      await new Promise(resolve => setTimeout(resolve, 1500)); // wait 1.5s for interval to trigger
+
+      const updatedValue = (await uptimeSeconds.get()).values[0].value;
+
+      expect(updatedValue).toBeGreaterThan(initialValue);
+    });
+  });
+});