test(auth): add test-only auth instance with testUtils plugin and initial tests

lib/auth/__tests__/auth.test.ts

@@ -0,0 +1,27 @@
+import { describe, it, expect, beforeAll } from "vitest"
+import { testAuth, getTestHelpers } from "@/lib/auth/test"
+import type { TestHelpers } from "better-auth/plugins"
+
+describe("Better-Auth integration", () => {
+  let test: TestHelpers
+
+  beforeAll(async () => {
+    test = await getTestHelpers()
+  })
+
+  it("should create a user", async () => {
+    const user = test.createUser({ email: "test@example.com" })
+    expect(user.email).toBe("test@example.com")
+  })
+
+  it("should create a session for a user", async () => {
+    const user = test.createUser({ email: "session-test@example.com" })
+    await test.saveUser(user)
+
+    const { session, headers } = await test.login({ userId: user.id })
+    expect(session.userId).toBe(user.id)
+    expect(headers.get("cookie")).toBeTruthy()
+
+    await test.deleteUser(user.id)
+  })
+})

lib/auth/test.ts

@@ -0,0 +1,21 @@
+import { betterAuth } from "better-auth"
+import { testUtils } from "better-auth/plugins"
+import { drizzleAdapter } from "@better-auth/drizzle-adapter"
+import { db } from "@/lib/db/index"
+
+export const testAuth = betterAuth({
+  database: drizzleAdapter(db, {
+    provider: "pg",
+  }),
+  plugins: [
+    testUtils({ captureOTP: true }),
+  ],
+  emailAndPassword: {
+    enabled: true,
+  },
+})
+
+export async function getTestHelpers() {
+  const ctx = await testAuth.$context
+  return ctx.test
+}

package.json

@@ -11,7 +11,9 @@
     "db:migrate": "drizzle-kit migrate",
     "db:studio": "drizzle-kit studio",
     "db:push": "drizzle-kit push",
-    "db:seed": "bun run lib/db/seed.ts"
+    "db:seed": "bun run lib/db/seed.ts",
+    "test": "vitest run",
+    "test:watch": "vitest"
   },
   "dependencies": {
     "@aws-sdk/client-s3": "^3.1036.0",
@@ -41,12 +43,14 @@
     "@types/pg": "^8.20.0",
     "@types/react": "^19",
     "@types/react-dom": "^19",
+    "@vitest/runner": "^4.1.5",
     "drizzle-kit": "^0.31.10",
     "eslint": "^9",
     "eslint-config-next": "16.2.4",
     "tailwindcss": "^4",
     "tsx": "^4.21.0",
-    "typescript": "^5"
+    "typescript": "^5",
+    "vitest": "^4.1.5"
   },
   "ignoreScripts": [
     "sharp",

vitest.config.ts

@@ -0,0 +1,15 @@
+import { defineConfig } from "vitest/config"
+import path from "path"
+
+export default defineConfig({
+  test: {
+    environment: "node",
+    globals: true,
+    setupFiles: [],
+  },
+  resolve: {
+    alias: {
+      "@": path.resolve(__dirname),
+    },
+  },
+})