test: lock in app health endpoint criteria (E00-S02-T03)

2026-08-29 00:21:34 +00:00
parent 9c049ce6b5
commit f7257f9258
2 changed files with 278 additions and 17 deletions
@@ -1,7 +1,7 @@
 /**
- * Docker Compose baseline test — locks in the [E00-S02-T01/T02] `docker
- * compose up -d` DB + app baseline and the PostgreSQL health gate for the
- * workspace.
+ * Docker Compose baseline test — locks in the [E00-S02-T01/T02/T03] `docker
+ * compose up -d` DB + app baseline, the PostgreSQL health gate and the app
+ * health endpoint for the workspace.
 *
 * Acceptance criteria covered (each test fails without the committed state):
 *   - "docker compose up -d starts the database" → the committed
@@ -16,10 +16,11 @@
 *     `compose.yaml` declares an `app` service built from the committed
 *     `apps/server/Dockerfile` (multi-stage: Node 24.19.0 bookworm-slim +
 *     frozen pnpm install → `tsc` build of `@personal-blog/server` →
- *     `node apps/server/dist/index.js`),
- *     with a published default port. The real-stack probe asserts the `app`
- *     container is created and starts cleanly (exit 0 when the placeholder
- *     process exits).
+ *     `node apps/server/dist/index.js`), with a published default port. Since
+ *     T03 the real-stack probe asserts the `app` container stays **running**
+ *     (the server now serves the health endpoint instead of exiting) and the
+ *     health endpoint answers HTTP 200 with a healthy body inside the
+ *     container.
 *   - "PostgreSQL health check gates application start" → the committed
 *     `compose.yaml` declares a `healthcheck` on the `db` service that probes
 *     readiness with `pg_isready` against the same credentials the database
@@ -315,7 +316,7 @@ test('compose.yaml exists, parses, and declares exactly the db and app services'
  assert.deepEqual(
    Object.keys(compose.services ?? {}).sort(),
    ['app', 'db'],
-    'compose.yaml must declare exactly the "db" and "app" services at T01',
+    'compose.yaml must declare exactly the "db" and "app" services at T01/T02/T03',
  );
 });

@@ -434,16 +435,44 @@ test('docker compose up -d starts the database and application containers', { sk
    const app = containers.find((c) => field(c, 'Service', 'service') === 'app');
    assert.ok(app, 'docker compose up -d must create the "app" container');
    const appState = String(field(app, 'State', 'state') ?? '');
-    const appExit = Number(field(app, 'ExitCode', 'exit_code', 'exitCode'));
-    if (/exited/i.test(appState)) {
-      assert.equal(
-        appExit,
-        0,
-        `the "app" container exited non-zero (exit ${appExit}) — the server entrypoint must start cleanly`,
-      );
-    } else {
-      assert.match(appState, /running|up/i, `the "app" container must start after "docker compose up -d" (state: "${appState}")`);
+    assert.match(
+      appState,
+      /running|up/i,
+      `the "app" container must stay running after "docker compose up -d" (state: "${appState}") — since T03 the server serves the health endpoint and must not exit`,
+    );
+
+    // T03: the app serves the health endpoint — HTTP smoke test against the
+    // endpoint inside the app container (no host-port dependency), polling
+    // until it answers or times out.
+    let healthOutput = '';
+    let healthOk = false;
+    for (let attempt = 0; attempt < 30 && !healthOk; attempt += 1) {
+      const probe = run('docker', ['compose', 'exec', '-T', 'app', 'node', '-e', `
+        fetch('http://127.0.0.1:3000/health')
+          .then(async (res) => { console.log(res.status, await res.text()); process.exit(res.ok ? 0 : 1); })
+          .catch(() => process.exit(2));
+      `], { cwd: REPO_ROOT, timeout: 15_000 });
+      const output = String(probe.stdout ?? '') + String(probe.stderr ?? '');
+      if (probe.status === 0) {
+        healthOk = true;
+        healthOutput = output;
+      } else if (probe.status === 1) {
+        healthOutput = output; // answered but not 2xx — fail fast
+        break;
+      } else {
+        run(process.execPath, ['-e', 'setTimeout(() => {}, 1000)']); // app still starting — retry
+      }
    }
+    assert.ok(
+      healthOk,
+      `GET /health must answer 2xx inside the app container once the stack is up (last probe: "${healthOutput.trim()}")`,
+    );
+    assert.match(healthOutput, /200/, `GET /health must return HTTP 200 (got: "${healthOutput.trim()}")`);
+    assert.match(
+      healthOutput,
+      /"status":"ok"/,
+      `GET /health must report a healthy application (got: "${healthOutput.trim()}")`,
+    );
  } finally {
    run('docker', ['compose', 'down'], { cwd: REPO_ROOT });
  }
@@ -0,0 +1,232 @@
+/**
+ * App health endpoint test — locks in the [E00-S02-T03] `GET /health`
+ * endpoint for the workspace server.
+ *
+ * Acceptance criteria covered (each test fails without the committed state):
+ *   - "app health endpoint succeeds" → the committed
+ *     `apps/server/src/index.ts` creates an HTTP server (`node:http`
+ *     `createServer`), listens on the application port (default 3000,
+ *     `PORT`-overridable) and answers `GET /health` with HTTP 200. The
+ *     "HTTP smoke test" boots the committed server source (Node type
+ *     stripping, no build step) on an ephemeral port and makes a real
+ *     `GET /health` request, asserting a 2xx response.
+ *   - "the endpoint reports a healthy application" → the `/health` response
+ *     body is JSON reporting a healthy application (`{"status":"ok"}`),
+ *     asserted statically against the committed source and by the smoke test.
+ *
+ * Run: `node --test tests/health-endpoint.test.mjs`
+ * (node:test — built into Node >= 18; no dependencies, lockfile untouched.)
+ */
+
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { spawn } from 'node:child_process';
+import { once } from 'node:events';
+import { createServer as createNetServer } from 'node:net';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const REPO_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
+
+const read = (relPath) => readFileSync(path.join(REPO_ROOT, relPath), 'utf8');
+
+/** The committed server entrypoint under test. */
+const SERVER_SRC = 'apps/server/src/index.ts';
+
+const delay = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
+
+// ---------------------------------------------------------------------------
+// Static assertions on the committed server entrypoint
+// ---------------------------------------------------------------------------
+
+/**
+ * Asserts the committed server entrypoint answers `GET /health` with HTTP 200
+ * and reports a healthy application. Fails fast on a missing/placeholder
+ * entrypoint; the mutation probes below prove the assertions are non-vacuous.
+ */
+function assertHealthEndpointSource(src) {
+  assert.match(
+    src,
+    /createServer\(/,
+    'the server entrypoint must create an HTTP server (node:http createServer)',
+  );
+  assert.match(
+    src,
+    /'\/health'/,
+    "the server entrypoint must route the health endpoint (GET /health)",
+  );
+  assert.match(
+    src,
+    /sendJson\(res, 200/,
+    'the health route must answer with HTTP 200 (app health endpoint succeeds)',
+  );
+  assert.match(
+    src,
+    /status:\s*'ok'/,
+    "the health payload must report a healthy application ({\"status\":\"ok\"})",
+  );
+  assert.match(
+    src,
+    /server\.listen\(/,
+    'the server entrypoint must start listening (server.listen)',
+  );
+  assert.match(
+    src,
+    /3000/,
+    'the server must default to the application port 3000 (Dockerfile EXPOSE / compose :3000)',
+  );
+}
+
+// ---------------------------------------------------------------------------
+// Boot helpers for the HTTP smoke test (Node type stripping, no build step)
+// ---------------------------------------------------------------------------
+
+/**
+ * How the current Node executes TypeScript sources: `default` (>= 23.6, type
+ * stripping on by default), `strip-types-flag` (>= 22.6 via
+ * `--experimental-strip-types`) or `null` (cannot run .ts at all). The
+ * workspace pins engines.node to 24.x, where type stripping is stable.
+ */
+function tsExecMode() {
+  const [major, minor] = process.versions.node.split('.').map(Number);
+  if (major > 23 || (major === 23 && minor >= 6)) return 'default';
+  if (major === 22 && minor >= 6) return 'strip-types-flag';
+  return null;
+}
+
+/** Reserves an ephemeral TCP port, then releases it for the child to bind. */
+function reservePort() {
+  return new Promise((resolve, reject) => {
+    const probe = createNetServer();
+    probe.once('error', reject);
+    probe.listen(0, '127.0.0.1', () => {
+      const address = probe.address();
+      const port = typeof address === 'object' && address !== null ? address.port : 0;
+      probe.close(() => resolve(port));
+    });
+  });
+}
+
+/**
+ * Boots the committed server source on `port`. Returns `{ child, stderr }`;
+ * the child writes its stderr into the `stderr()` closure for diagnostics.
+ */
+function bootServer(port) {
+  const args =
+    tsExecMode() === 'strip-types-flag'
+      ? ['--experimental-strip-types', SERVER_SRC]
+      : [SERVER_SRC];
+  const child = spawn(process.execPath, args, {
+    cwd: REPO_ROOT,
+    env: { ...process.env, PORT: String(port) },
+    stdio: ['ignore', 'ignore', 'pipe'],
+  });
+  let stderr = '';
+  child.stderr.on('data', (chunk) => {
+    stderr += String(chunk);
+  });
+  return { child, stderr: () => stderr };
+}
+
+/**
+ * Polls `GET /health` until it answers or the child exits / the deadline
+ * passes (poll with timeout — no flaky sleeps).
+ */
+async function waitForHealth(port, child, stderr) {
+  const deadline = Date.now() + 10_000;
+  let lastError = '';
+  while (Date.now() < deadline) {
+    if (child.exitCode !== null) {
+      throw new Error(
+        `the server exited before answering GET /health (code ${child.exitCode}): ${stderr().trim()}`,
+      );
+    }
+    try {
+      return await fetch(`http://127.0.0.1:${port}/health`, {
+        signal: AbortSignal.timeout(1_000),
+      });
+    } catch (err) {
+      lastError = err instanceof Error ? err.message : String(err);
+      await delay(100);
+    }
+  }
+  throw new Error(
+    `GET /health did not answer within 10s (last error: ${lastError}; server stderr: ${stderr().trim()})`,
+  );
+}
+
+// ---------------------------------------------------------------------------
+// Criterion tests
+// ---------------------------------------------------------------------------
+
+test('the app health endpoint succeeds (committed entrypoint answers GET /health with HTTP 200)', () => {
+  assertHealthEndpointSource(read(SERVER_SRC));
+});
+
+test('the endpoint reports a healthy application (committed health payload is {"status":"ok"})', () => {
+  const src = read(SERVER_SRC);
+  assert.match(
+    src,
+    /status:\s*'ok'/,
+    "the health payload must report a healthy application ({\"status\":\"ok\"})",
+  );
+});
+
+test('an HTTP smoke test against the booted server succeeds for GET /health (200 + healthy body)', async (t) => {
+  if (!tsExecMode()) {
+    t.skip(
+      `Node ${process.versions.node} cannot execute TypeScript sources; the workspace pins engines.node to 24.x (type stripping is stable there)`,
+    );
+    return;
+  }
+  const port = await reservePort();
+  const { child, stderr } = bootServer(port);
+  try {
+    const response = await waitForHealth(port, child, stderr);
+    assert.equal(
+      response.status,
+      200,
+      `GET /health must succeed with HTTP 200 (got ${response.status})`,
+    );
+    const body = await response.json();
+    assert.equal(
+      body.status,
+      'ok',
+      'the health endpoint must report a healthy application ({"status":"ok"})',
+    );
+  } finally {
+    child.kill('SIGTERM');
+    await Promise.race([once(child, 'exit'), delay(2_000)]);
+    if (child.exitCode === null && child.signalCode === null) child.kill('SIGKILL');
+  }
+});
+
+// ---------------------------------------------------------------------------
+// Non-vacuous probes — the assertions above really do fail on violations
+// ---------------------------------------------------------------------------
+
+test('removing the /health route makes the health-endpoint criterion fail (mutation probe)', () => {
+  const src = read(SERVER_SRC);
+  const withoutRoute = src.replace(/'\/health'/, "'/nope'");
+  assert.notEqual(withoutRoute, src, 'the mutation must actually replace the /health route');
+  assert.throws(() => assertHealthEndpointSource(withoutRoute), /\/health/);
+});
+
+test('removing the HTTP 200 makes the health-endpoint criterion fail (mutation probe)', () => {
+  const src = read(SERVER_SRC);
+  const without200 = src.replace(/sendJson\(res, 200/, 'sendJson(res, 500');
+  assert.notEqual(without200, src, 'the mutation must actually change the health status code');
+  assert.throws(() => assertHealthEndpointSource(without200), /HTTP 200/);
+});
+
+test('removing the healthy report makes the healthy-report criterion fail (mutation probe)', () => {
+  const src = read(SERVER_SRC);
+  const withoutOk = src.replace(/status:\s*'ok'/, "status: 'nope'");
+  assert.notEqual(withoutOk, src, 'the mutation must actually change the health payload');
+  assert.throws(() => assertHealthEndpointSource(withoutOk), /healthy application/);
+});
+
+test('a placeholder entrypoint (no server at all) fails the health-endpoint criterion (mutation probe)', () => {
+  assert.throws(() => assertHealthEndpointSource('export {};\n'), /createServer/);
+});