fix(healthcheck): correct arrow syntax and add unit tests

sample-docker-compose.yml

@@ -11,9 +11,11 @@ services:
     container_name: river_rooks_web
     restart: unless-stopped
     healthcheck:
-      test: ["CMD", "node", "healthcheck.js"]
+      test: ["CMD", "node", "test/healthcheck.js"]
       interval: 30s
       timeout: 3s
+      start_period: 3s
+      retries: 3
     environment:
       - "SITE_DOMAIN=${SITE_DOMAIN:?Error: SITE_DOMAIN is not set. Please define SITE_DOMAIN in .env}"
       - "SITE_URL=${SITE_URL:-https://${SITE_DOMAIN}}"

test/healthcheck.js

@@ -1,5 +1,5 @@
 const port = process.env.PORT || 8080;
 
 fetch(`http://127.0.0.1:${port}/healthz`)
-	.then((res)) => process.exit(res.ok ? 0:1))
+  .then((res) => process.exit(res.ok ? 0 : 1))
-	.catch(() process.exit(1));
+  .catch(() => process.exit(1));

test/healthcheck.test.js

@@ -0,0 +1,79 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import path from "node:path";
+import http from "node:http";
+import { spawn } from "node:child_process";
+
+test("Healthcheck: test/healthcheck.js script exists and parses cleanly", () => {
+  const scriptPath = path.resolve(process.cwd(), "test/healthcheck.js");
+  assert.ok(fs.existsSync(scriptPath), "test/healthcheck.js must exist");
+
+  const content = fs.readFileSync(scriptPath, "utf-8");
+  assert.match(content, /127\.0\.0\.1/, "Must target IPv4 loopback 127.0.0.1 to avoid Alpine IPv6 lookup failures");
+  assert.match(content, /\/healthz/, "Must target the /healthz endpoint");
+});
+
+test("Healthcheck: test/healthcheck.js succeeds when server returns 200 OK", async () => {
+  const scriptPath = path.resolve(process.cwd(), "test/healthcheck.js");
+  
+  // Start dummy HTTP server responding 200 on /healthz
+  const server = http.createServer((req, res) => {
+    if (req.url === "/healthz") {
+      res.writeHead(200, { "Content-Type": "application/json" });
+      res.end(JSON.stringify({ status: "ok" }));
+    } else {
+      res.writeHead(404);
+      res.end();
+    }
+  });
+
+  await new Promise((resolve) => server.listen(0, "127.0.0.1", resolve));
+  const port = server.address().port;
+
+  try {
+    const exitCode = await new Promise((resolve) => {
+      const child = spawn(process.execPath, [scriptPath], {
+        env: { ...process.env, PORT: String(port) },
+      });
+      child.on("close", resolve);
+    });
+
+    assert.strictEqual(exitCode, 0, "healthcheck.js must exit with code 0 on healthy endpoint");
+  } finally {
+    await new Promise((resolve) => server.close(resolve));
+  }
+});
+
+test("Healthcheck: test/healthcheck.js fails when connection is refused or server is 500", async () => {
+  const scriptPath = path.resolve(process.cwd(), "test/healthcheck.js");
+
+  // Pick an unused high port
+  const exitCodeDown = await new Promise((resolve) => {
+    const child = spawn(process.execPath, [scriptPath], {
+      env: { ...process.env, PORT: "59999" },
+    });
+    child.on("close", resolve);
+  });
+  assert.strictEqual(exitCodeDown, 1, "healthcheck.js must exit with code 1 when server is unreachable");
+
+  // Test 500 status code
+  const server = http.createServer((req, res) => {
+    res.writeHead(500);
+    res.end();
+  });
+  await new Promise((resolve) => server.listen(0, "127.0.0.1", resolve));
+  const port = server.address().port;
+
+  try {
+    const exitCode500 = await new Promise((resolve) => {
+      const child = spawn(process.execPath, [scriptPath], {
+        env: { ...process.env, PORT: String(port) },
+      });
+      child.on("close", resolve);
+    });
+    assert.strictEqual(exitCode500, 1, "healthcheck.js must exit with code 1 on HTTP 500");
+  } finally {
+    await new Promise((resolve) => server.close(resolve));
+  }
+});