Add Jest to support backend unit tests

backend/jest.config.ts

@@ -0,0 +1,17 @@
+import type { Config } from "@jest/types"
+
+const config: Config.InitialOptions = {
+  preset: "ts-jest",
+  testEnvironment: "node",
+  verbose: true,
+  automock: false,
+  collectCoverage: true,
+  collectCoverageFrom: ["./src/**/**.ts"],
+  coverageProvider: "v8",
+  coverageThreshold: {
+    global: {
+      lines: 90
+    }
+  }
+}
+export default config;

backend/package.json

@@ -20,11 +20,11 @@
   ],
   "main": "index.ts",
   "scripts": {
-    "tsc": "./node_modules/typescript/bin/tsc",
+    "tsc": "./node_modules/typescript/bin/tsc -p tsconfig.build.json",
     "build": "npm run tsc",
     "start": "node --max-old-space-size=2048 dist/index.js",
     "start-production": "node --max-old-space-size=4096 dist/index.js",
-    "test": "echo \"Error: no test specified\" && exit 1",
+    "test": "./node_modules/.bin/jest --coverage",
     "lint": "./node_modules/.bin/eslint . --ext .ts",
     "lint:fix": "./node_modules/.bin/eslint . --ext .ts --fix",
     "prettier": "./node_modules/.bin/prettier --write \"src/**/*.{js,ts}\""
@@ -46,11 +46,15 @@
     "@types/compression": "^1.7.2",
     "@types/crypto-js": "^4.1.1",
     "@types/express": "^4.17.13",
+    "@types/jest": "^28.1.4",
     "@types/ws": "~8.5.3",
     "@typescript-eslint/eslint-plugin": "^5.30.5",
     "@typescript-eslint/parser": "^5.30.5",
     "eslint": "^8.19.0",
     "eslint-config-prettier": "^8.5.0",
-    "prettier": "^2.7.1"
+    "jest": "^28.1.2",
+    "prettier": "^2.7.1",
+    "ts-jest": "^28.0.5",
+    "ts-node": "^10.8.2"
   }
 }

backend/tsconfig.json

@@ -3,6 +3,7 @@
     "types": ["node"],
     "module": "commonjs",
     "target": "esnext",
+    "types": ["node", "jest"],
     "lib": ["es2019", "dom"],
     "strict": true,
     "noImplicitAny": false,