chore: Set up unit testing (#22)

.github/workflows/test.yml

@@ -22,3 +22,16 @@ jobs:
       - run: npm ci
       - run: npm run build
       - run: npm run lint
+
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+      - run: npm ci
+      - run: npm run build
+      - run: npm run test

backend/package.json

@@ -20,7 +20,8 @@
   },
   "scripts": {
     "build": "node -e \"fs.rmSync('./dist',{force:true,recursive:true})\" && tsc",
-    "lint": "tsc --noEmit -p tsconfig.lint.json && eslint --ignore-path .gitignore ."
+    "lint": "tsc --noEmit -p tsconfig.lint.json && eslint --ignore-path .gitignore .",
+    "test": "mocha --require tsx --recursive \"test/**/*.ts\""
   },
   "dependencies": {
     "pino-pretty": "11.2.1",

backend/test/util/mutex.test.ts

@@ -0,0 +1,40 @@
+import { Mutex } from '../../src/util/mutex.js'
+import assert from 'node:assert'
+
+describe('util/mutex.ts', () => {
+  describe('Mutex', () => {
+    it('serializes access to a critical section', async () => {
+      let locked = false
+      const mutex = new Mutex()
+      const unlock = await mutex.lock()
+      locked = true
+      setTimeout(() => {
+        unlock()
+        locked = false
+      }, 100)
+      const unlock2 = await mutex.lock()
+      assert.strictEqual(locked, false)
+      unlock2()
+    })
+
+    it('resolves in the order of lock calls', async () => {
+      const mutex = new Mutex()
+      let order = ''
+      const promises: Array<Promise<any>> = []
+      promises.push(mutex.lock().then((unlock) => {
+        order += '1'
+        setTimeout(unlock, 50)
+      }))
+      promises.push(mutex.lock().then((unlock) => {
+        order += '2'
+        setTimeout(unlock, 50)
+      }))
+      promises.push(mutex.lock().then((unlock) => {
+        order += '3'
+        setTimeout(unlock, 50)
+      }))
+      await Promise.all(promises)
+      assert.strictEqual(order, '123')
+    })
+  })
+})