Refactor VPN proxy client implementation

test/server/prometheus-metrics.test.js

@@ -1,9 +1,11 @@
 import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
 import test from 'node:test';
 import {
   renderPrometheusMetrics,
   sendPrometheusMetrics,
-} from '../../src/server/prometheusMetrics.js';
+} from '../../dist/server/prometheusMetrics.js';
+import { createPrometheusMetricsRoute } from '../../dist/server/http/routes/prometheusMetricsRoute.js';
 
 const observedAt = '2026-08-08T10:00:00.000Z';
 const snapshot = {
@@ -98,3 +100,97 @@ test('invalid canonical counters fail the scrape instead of publishing corrupt v
     /Invalid Prometheus counter/,
   );
 });
+
+function routeResponse() {
+  return {
+    writeHead(status, headers) {
+      this.status = status;
+      this.headers = headers;
+    },
+    end(body) {
+      this.body = body;
+    },
+  };
+}
+
+test('Prometheus route reads one current snapshot and preserves the exact text contract', async () => {
+  let reads = 0;
+  let refreshes = 0;
+  const route = createPrometheusMetricsRoute({
+    deviceInventory: {
+      metricsSnapshot: () => {
+        reads += 1;
+        return snapshot;
+      },
+      refresh: () => { refreshes += 1; },
+    },
+  });
+  const res = routeResponse();
+  assert.equal(await route.handle({ method: 'GET', url: '/metrics?source=prometheus' }, res), true);
+  assert.equal(reads, 1);
+  assert.equal(refreshes, 0);
+  assert.equal(res.status, 200);
+  assert.equal(res.headers['content-type'], 'text/plain; version=0.0.4; charset=utf-8');
+  assert.equal(res.body, renderPrometheusMetrics(snapshot));
+  assert.equal(res.body.endsWith('\n'), true);
+});
+
+test('Prometheus route preserves path, method and nullable inventory gating', async () => {
+  let reads = 0;
+  const route = createPrometheusMetricsRoute({
+    deviceInventory: { metricsSnapshot: () => { reads += 1; return snapshot; } },
+  });
+  for (const url of ['/metrics/', '/api/metrics', '/']) {
+    assert.equal(await route.handle({ method: 'GET', url }, routeResponse()), false);
+  }
+  await assert.rejects(
+    route.handle({ method: 'POST', url: '/metrics' }, routeResponse()),
+    (error) => error.code === 'ENDPOINT_NOT_FOUND',
+  );
+  assert.equal(reads, 0);
+
+  const clientRoute = createPrometheusMetricsRoute({ deviceInventory: null });
+  await assert.rejects(
+    clientRoute.handle({ method: 'GET', url: '/metrics' }, routeResponse()),
+    (error) => error.code === 'ENDPOINT_NOT_FOUND',
+  );
+});
+
+test('Prometheus route propagates snapshot and renderer failures unchanged', async () => {
+  const snapshotError = new Error('snapshot failed');
+  const snapshotRoute = createPrometheusMetricsRoute({
+    deviceInventory: { metricsSnapshot: () => { throw snapshotError; } },
+  });
+  await assert.rejects(
+    snapshotRoute.handle({ method: 'GET', url: '/metrics' }, routeResponse()),
+    (error) => error === snapshotError,
+  );
+
+  const rendererRoute = createPrometheusMetricsRoute({
+    deviceInventory: {
+      metricsSnapshot: () => ({ traffic: { gatewayBytes: 'broken', proxyBytes: '0' } }),
+    },
+  });
+  await assert.rejects(
+    rendererRoute.handle({ method: 'GET', url: '/metrics' }, routeResponse()),
+    /Invalid Prometheus counter/,
+  );
+});
+
+test('Prometheus route is the sole HTTP owner before API and static fallback', () => {
+  const index = readFileSync(new URL('../../src/server/index.ts', import.meta.url), 'utf8');
+  const route = readFileSync(
+    new URL('../../src/server/http/routes/prometheusMetricsRoute.ts', import.meta.url),
+    'utf8',
+  );
+  assert.match(index, /createPrometheusMetricsRoute\(\{ deviceInventory \}\)/);
+  const delegation = index.indexOf('prometheusMetricsRoute.handle(req, res)');
+  const apiDispatch = index.indexOf("requestUrl.pathname.startsWith('/api/')");
+  const staticFallback = index.indexOf(': serveStatic(req, res)');
+  assert.ok(delegation >= 0 && delegation < apiDispatch && apiDispatch < staticFallback);
+  assert.doesNotMatch(index, /['"]\/metrics['"]/);
+  assert.doesNotMatch(index, /metricsSnapshot\(\)|sendPrometheusMetrics/);
+  assert.match(route, /pathname !== '\/metrics'/);
+  assert.match(route, /deviceInventory\.metricsSnapshot\(\)/);
+  assert.doesNotMatch(route, /\.refresh\(/);
+});