diff --git a/tests/helpers/build-test-app.ts b/tests/helpers/build-test-app.ts
index d2e6849..02b1a21 100644
--- a/tests/helpers/build-test-app.ts
+++ b/tests/helpers/build-test-app.ts
@@ -4,9 +4,29 @@ import { authRoutes } from '../../src/routes/auth.js';
 import type { MockDb } from '../test-utils.js';
 import { createMockDb } from '../test-utils.js';
 
+/** Mock Redis for login lockout in auth tests. Implements ttl, setex, del, eval. */
+const mockRedis = {
+  async ttl(_key: string): Promise<number> {
+    return -2; // key does not exist -> not blocked
+  },
+  async setex(_key: string, _ttl: number, _value: string): Promise<'OK'> {
+    return 'OK';
+  },
+  async del(..._keys: string[]): Promise<number> {
+    return 0;
+  },
+  async eval(
+    _script: string,
+    _keysCount: number,
+    ..._keysAndArgs: string[]
+  ): Promise<number[]> {
+    return [0, 0, 0]; // counters below threshold
+  },
+};
+
 /**
  * Build a minimal Fastify app for auth route integration tests.
- * Uses mock db and rate limit options (no actual rate limiting).
+ * Uses mock db, mock Redis for login lockout, and rate limit options (no actual rate limiting).
  */
 export async function buildAuthTestApp(mockDb?: MockDb): Promise<FastifyInstance> {
   const db = mockDb ?? createMockDb();
@@ -31,8 +51,8 @@ export async function buildAuthTestApp(mockDb?: MockDb): Promise<FastifyInstance
   });
 
   app.decorate('db', db);
+  app.decorate('redis', mockRedis);
   app.decorate('rateLimitOptions', {
-    login: { max: 100, timeWindow: '1 minute' },
     register: { max: 100, timeWindow: '1 hour' },
     forgotPassword: { max: 100, timeWindow: '1 hour' },
     verifyEmail: { max: 100, timeWindow: '15 minutes' },