feat: chat repo

- setup mongodb
- implement chat repo and test
- use dotenv in jest
- CI add mongodb

.github/workflows/ci.yaml

@@ -9,6 +9,20 @@ on:
 
 jobs:
   test:
+    services:
+      mongo:
+        image: mongo:6.0.20
+        ports:
+        - 27017:27017
+        # health check
+        # ref: https://engineering.synatic.com/a-simple-way-to-run-a-mongodb-replica-set-in-github-actions
+        options: >-
+          --health-cmd "mongosh --eval 'db.runCommand(\"ping\")'"
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+    env:
+      MONGODB_URI: mongodb://localhost:27017
     strategy:
       matrix:
         directory: [ "./backend" ]

backend/.env.example

@@ -0,0 +1 @@
+MONGODB_URI=mongodb://localhost:27017

backend/README.md

@@ -0,0 +1,17 @@
+# Backend
+## Run at Local
+### Setup Infrastructure
+```bash
+cp .env.example .env  # modify .env as needed
+docker run --name mongodb -p 27017:27017 -d mongo:6.0.20
+```
+
+### Run server
+```bash
+npm run start
+```
+
+### Run tests
+```bash
+npm run test
+```

backend/jest.config.js

@@ -8,5 +8,6 @@ module.exports = {
     transform: {
       "^.+.tsx?$": ["ts-jest",{}],
     },
+    setupFiles: ["dotenv/config"]
   };
 

backend/package.json

@@ -15,8 +15,10 @@
         "@types/body-parser": "^1.19.5",
         "@types/express": "^5.0.0",
         "@types/node": "^22.10.7",
+        "dotenv": "^16.4.7",
         "express": "^4.21.2",
         "mathjs": "^14.0.1",
+        "mongodb": "^6.12.0",
         "pino": "^9.6.0",
         "socket.io": "^4.8.1"
     },

backend/src/command-service.spec.ts

@@ -6,8 +6,15 @@ const mockRepository = {
     getLatest: jest.fn(),
 };
 
+type TestCase = {
+    command: string;
+    expected?: string;
+    hasError?: boolean;
+};
+
 describe('evaluate', () => {
-    describe.each([
+    const logger = pino();
+    describe.each<TestCase>([
         { command: '', hasError: true },
         { command: ' ', hasError: true },
         { command: '1', expected: '1' },
@@ -30,13 +37,14 @@ describe('evaluate', () => {
         { command: '5 * 7 / 3 * 3', expected: '35' },
 
     ])('.evaluate($command)', ({ command, hasError, expected }) => {
-        test(`returns ${hasError}`, () => {
+        test(`returns ${hasError}`, async () => {
             const clientId = 'whatever';
-            const commandService = new CommandService(pino(), mockRepository);
+            const commandService = new CommandService(logger, mockRepository);
             if (hasError) {
-                expect(() => commandService.evaluateAndSave(clientId, command)).toThrow('Invalid command');
+                await expect(commandService.evaluateAndSave(clientId, command)).rejects.toThrow('Invalid command');
             } else {
-                expect(commandService.evaluateAndSave(clientId, command)).toBe(expected);
+                const res = await commandService.evaluateAndSave(clientId, command);
+                expect(res).toBe(expected);
                 expect(mockRepository.saveCommand).toHaveBeenCalledWith(clientId, command, expected);
             }
         });

backend/src/command-service.ts

@@ -1,13 +1,7 @@
 import { Logger } from "pino";
 import { evaluate as evaluateMathjs } from 'mathjs';
 import { CommandAndResult } from "./entities/command-result.entity";
-
-interface IRepository {
-    saveCommand(clientId: string, command: string, result: string): void;
-    getLatest(clientId: string, count: number): CommandAndResult[];
-}
-
-const historyCount = 10;
+import { IRepository } from "./repositories";
 
 class CommandService {
     private operators = new Set(['+', '-', '*', '/']);
@@ -19,15 +13,15 @@ class CommandService {
     }
 
     // evaluateAndSave evaluates a mathematical expression and saves the result to the repository
-    public evaluateAndSave(clientId: string, expression: string): string {
+    public async evaluateAndSave(clientId: string, expression: string): Promise<string> {
         const result = this.evaluate(expression);
-        this.repository.saveCommand(clientId, expression, result);
+        await this.repository.saveCommand(clientId, expression, result);
         return result;
     }
 
     // getHistory returns the latest 10 commands for a client
-    public getHistory(clientId: string): CommandAndResult[] {
-        return this.repository.getLatest(clientId, historyCount);
+    public async getHistory(clientId: string): Promise<CommandAndResult[]> {
+        return this.repository.getLatest(clientId);
     }
 
     // evaluate evaluate a mathematical expression