Add healthz tests

test/health.test.ts

@@ -0,0 +1,40 @@
+import * as httpserver from "./httpserver"
+import * as integration from "./integration"
+
+describe("health", () => {
+  let codeServer: httpserver.HttpServer | undefined
+
+  afterEach(async () => {
+    if (codeServer) {
+      await codeServer.close()
+      codeServer = undefined
+    }
+  })
+
+  it("/healthz", async () => {
+    ;[, , codeServer] = await integration.setup(["--auth=none"], "")
+    const resp = await codeServer.fetch("/healthz")
+    expect(resp.status).toBe(200)
+    const json = await resp.json()
+    expect(json).toStrictEqual({ lastHeartbeat: 0, status: "expired" })
+  })
+
+  it("/healthz (websocket)", async () => {
+    ;[, , codeServer] = await integration.setup(["--auth=none"], "")
+    const ws = codeServer.ws("/healthz")
+    const message = await new Promise((resolve, reject) => {
+      ws.on("error", console.error)
+      ws.on("message", (message) => {
+        try {
+          const j = JSON.parse(message.toString())
+          resolve(j)
+        } catch (error) {
+          reject(error)
+        }
+      })
+      ws.on("open", () => ws.send(JSON.stringify({ event: "health" })))
+    })
+    ws.terminate()
+    expect(message).toStrictEqual({ event: "health", status: "expired", lastHeartbeat: 0 })
+  })
+})