Merge pull request #31 from TanvikaOjha/fix/cacheGet

fix: safely handle corrupt json cache entries in cacheGet

Author: Abioladory123

src/__tests__/redis.test.ts

@@ -0,0 +1,42 @@
+import { cacheGet } from './redis';
+import { redis } from './redis'; // or your Redis client module
+
+describe('cacheGet', () => {
+  const testKey = 'test-corrupt-entry';
+  const fullKey = `cache:${testKey}`;
+
+  afterEach(async () => {
+    await redis.del(fullKey);
+    jest.restoreAllMocks();
+  });
+
+  it('should return parsed data for a valid cache entry', async () => {
+    const data = { id: 123, name: 'Alice' };
+    await redis.set(fullKey, JSON.stringify(data));
+
+    const result = await cacheGet<{ id: number; name: string }>(testKey);
+    expect(result).toEqual(data);
+  });
+
+  it('should handle malformed JSON safely by logging, deleting the key, and returning null', async () => {
+    // 1. Seed a corrupted JSON entry in Redis
+    const corruptedValue = '{ "id": 123, "name": invalid_json ';
+    await redis.set(fullKey, corruptedValue);
+
+    const warnSpy = jest.spyOn(console, 'warn').mockImplementation(() => {});
+
+    // 2. Call cacheGet — should NOT throw
+    const result = await cacheGet(testKey);
+
+    // 3. Verify acceptance criteria
+    expect(result).toBeNull();
+    expect(warnSpy).toHaveBeenCalledWith(
+      expect.stringContaining(`Failed to parse cached JSON for key "${fullKey}"`),
+      expect.any(Error)
+    );
+
+    // 4. Verify the corrupted key was evicted from Redis
+    const remainingKey = await redis.get(fullKey);
+    expect(remainingKey).toBeNull();
+  });
+});

src/redis.ts

@@ -75,9 +75,25 @@ export async function cacheSet(key: string, value: unknown, ttlSeconds: number):
  * Retrieve a cached JSON value. Returns null on miss.
  */
 export async function cacheGet<T>(key: string): Promise<T | null> {
+  const fullKey = `cache:${key}`;
   const raw = await redis.get(`cache:${key}`);
   if (!raw) return null;
-  return JSON.parse(raw) as T;
+
+  try{
+    return JSON.parse(raw) as T;
+  }
+  catch(error) {
+   console.warn(`[Cache Error] Failed to parse cached JSON for key "${fullKey}". Evicting corrupted key.`, error)
+
+  };
+
+  // Deleting the corrupted key so subsequent requests repopulate it safely 
+  try {
+  await redis.del(fullKey);
+  } catch (delError) {
+    console.error(`[Cache Error] Failed to delete corrupted key "${fullKey}":`, delError);
+  }
+  return null;
 }
 
 /**