feat: graceful shutdown and integration test

backend/package.json

@@ -32,6 +32,7 @@
         "ts-jest": "^29.2.5",
         "ts-node": "^10.9.2",
         "typescript": "^5.7.3",
-        "typescript-eslint": "^8.21.0"
+        "typescript-eslint": "^8.21.0",
+        "socket.io-client": "^4.8.1"
     }
 }

backend/src/app.spec.ts

@@ -0,0 +1,73 @@
+import { ChatServer } from "./chat-server";
+import CommandService from "./command-service";
+import ChatRepo, { ChatSession } from "./repositories/chat-repo";
+import { pino } from "pino";
+import { io as ioc, type Socket as ClientSocket } from "socket.io-client";
+import { MongoClient } from "mongodb";
+
+describe("App Integration Test", () => {
+    let chatServer: ChatServer;
+    let mongoClient: MongoClient;
+    let clientSocket: ClientSocket;
+    let close: () => void;
+    const mongoUri = process.env.MONGODB_URI || "mongodb://localhost:27017";
+    const serverPort = 3001;
+    const serverUri = `http://localhost:${serverPort}`;
+
+    beforeAll(async () => {
+        const dbName = "test" + Date.now();
+        const collectionName = "chat-session";
+        const logger = pino();
+        mongoClient = await new MongoClient(mongoUri).connect();
+        logger.info("Connected to MongoDB");
+        const db = mongoClient.db(dbName);
+        const collection = db.collection<ChatSession>(collectionName);
+        const commandService = new CommandService(logger, new ChatRepo(collection));
+        chatServer = new ChatServer(logger, commandService, serverPort);
+        close = chatServer.listen();
+    });
+
+    beforeEach(async () => {
+        clientSocket = await ioc(serverUri).connect();
+    });
+
+    afterEach(async () => {
+        await clientSocket.close();
+    });
+
+    afterAll(async () => {
+        await close();
+        await mongoClient.close();
+    });
+
+    it("should return result", (done: jest.DoneCallback) => {
+        clientSocket.on("result", (arg) => {
+            expect(arg).toBe("2");
+            done();
+        });
+        clientSocket.emit("operation", "1+1");
+    });
+    it("should return error", (done: jest.DoneCallback) => {
+        clientSocket.on("error", (arg) => {
+            expect(arg).toBe("Invalid command");
+            done();
+        });
+        clientSocket.emit("operation", "1--2");
+    });
+    it("should return history", (done: jest.DoneCallback) => {
+        const expected = [{ expression: "1+1", result: "2" }, { expression: "2+3", result: "5" }];
+
+        clientSocket.on("result", (arg) => {
+            if (arg===expected[expected.length-1].result) {
+                clientSocket.emit("history");
+            }
+        });
+        clientSocket.on("history", (arg) => {
+            expect(arg).toEqual(expected);
+            done();
+        });
+
+        clientSocket.emit("operation", "1+1"); // step 1
+        clientSocket.emit("operation", "2+3"); // step 2
+    });
+});

backend/src/app.ts

@@ -9,20 +9,30 @@ const uri = process.env.MONGODB_URI || "mongodb://localhost:27017";
 const dbName = "math-chat";
 const collectionName = "chat-session";
 
-async function getMongoCollection(uri: string, dbName: string, collectionName: string): Promise<Collection<ChatSession>> {
-    const mongoClient = new MongoClient(uri);
-    await mongoClient.connect();
+async function getMongoCollection(mongoClient: MongoClient, dbName: string, collectionName: string): Promise<Collection<ChatSession>> {
     const db = mongoClient.db(dbName);
     const collection = db.collection<ChatSession>(collectionName);
     return collection;
 }
+function connectMongo(uri: string): Promise<MongoClient> {
+    return new MongoClient(uri).connect();
+}
 
 async function main() {
     const logger = pino();
-    const collection = await getMongoCollection(uri, dbName, collectionName);
+    const mongoClient = await connectMongo(uri);
+    const collection = await getMongoCollection(mongoClient, dbName, collectionName);
     const commandService = new CommandService(logger, new ChatRepo(collection));
     const chatServer = new ChatServer(logger, commandService, 3000);
-    chatServer.listen();
+    const serverClose = await chatServer.listen();
+
+    // graceful shutdown
+    const shutdown = () => {
+        serverClose();
+        mongoClient.close();
+    }
+    process.on('SIGTERM', shutdown);
+    process.on('SIGINT', shutdown);
 }
 
 main();

backend/src/chat-server.ts

@@ -60,7 +60,7 @@ export class ChatServer {
 
     public listen() {
         const httpServer = this.app.listen(this.port,
-            () => { console.log(`Server listening on port ${this.port}`) }
+            () => { this.logger.info(`Server listening on port ${this.port}`) }
         );
 
         // Express server and socket.io server is sharing the same http server
@@ -70,5 +70,10 @@ export class ChatServer {
             }
         });
         this.setupSocketHandler(io);
+        return async function close() {
+            httpServer.close();
+            await io.close();
+        }
     }
 }
+