Set up Vitest for unit testing

.github/workflows/test-backend.yml

@@ -0,0 +1,33 @@
+name: Test (backend)
+on:
+  push:
+    branches: [main]
+    paths: ["backend/**"]
+  pull_request:
+    paths: ["backend/**"]
+
+jobs:
+  lint:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v6
+
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          cache: "npm"
+          cache-dependency-path: backend/package.json
+
+      - name: Install NPM packages
+        working-directory: backend
+        run: npm ci
+
+      - name: Run code generators
+        working-directory: backend
+        run: DATABASE_URL=placeholder npx prisma generate
+
+      - name: Test
+        working-directory: backend
+        run: npm run test

.vscode/extensions.json

@@ -7,6 +7,7 @@
     "Prisma.prisma",
     "redhat.vscode-yaml",
     "dbaeumer.vscode-eslint",
-    "timonwong.shellcheck"
+    "timonwong.shellcheck",
+    "vitest.explorer"
   ]
 }

backend/eslint.config.js

@@ -52,7 +52,7 @@ export default defineConfig({
           },
           {
             from: "db",
-            allow: ["db/errors", "env"],
+            allow: ["db/errors"],
           },
           {
             from: "handlers",
@@ -70,7 +70,7 @@ export default defineConfig({
           },
           {
             from: "services",
-            allow: ["db/errors", "services/errors", "lib", "env"],
+            allow: ["db/errors", "services/errors", "lib"],
           },
           {
             from: ["lib", "handlers", "services"],
@@ -79,7 +79,7 @@ export default defineConfig({
           },
           {
             from: "services/index",
-            allow: ["db", "services"],
+            allow: ["db", "services", "env"],
           },
           {
             from: "*",
@@ -98,6 +98,10 @@ export default defineConfig({
             from: "index",
             allow: ["env", "db", "server", "services/index"],
           },
+          {
+            from: "test",
+            allow: "*",
+          },
         ],
       },
     ],
@@ -147,6 +151,8 @@ export default defineConfig({
       { type: "server", pattern: "server/**" },
       // Environment variables
       { type: "env", pattern: "src/lib/env.ts", mode: "full" },
+      // Vitest test files
+      { type: "test", pattern: "test/**" },
     ],
   },
 });