Add event handlers to redis client

If certain event handlers aren't defined on the client before
connecting, the app will crash on disconnect event (e.g., timeout).

Issue comment regarding issue details from node-redis repo:
redis/node-redis#2032 (comment)

Fixes #129, #160

.changeset/sixty-suns-brush.md

@@ -0,0 +1,5 @@
+---
+'@shopify/shopify-app-session-storage-redis': patch
+---
+
+Add event handlers to redis client to prevent crashing on disconnect event. Fixes #129, #160 (Thanks to @davidhollenbeckx for linking to issue and solution.)

packages/shopify-app-session-storage-redis/src/__tests__/redis.conf

@@ -1 +1,2 @@
 user shopify on +@all allkeys  >passify
+timeout 2

packages/shopify-app-session-storage-redis/src/__tests__/redis.test.ts

@@ -35,6 +35,10 @@ describe('RedisSessionStorage', () => {
     await wait(10000);
 
     client = createClient({url: dbURL.toString()});
+    client.on('error', (err) => {});
+    client.on('connect', () => {});
+    client.on('reconnecting', () => {});
+    client.on('ready', () => {});
     await client.connect();
   });
 
@@ -161,6 +165,32 @@ describe('RedisSessionStorage', () => {
     storageClone1.disconnect();
     storageClone2.disconnect();
   });
+
+  it(`reconnects after a timeout`, async () => {
+    const storage = new RedisSessionStorage(dbURL);
+    await storage.ready;
+
+    const sessionId = 'timeout_connection_test';
+    const session = new Session({
+      id: sessionId,
+      shop: 'shop1.myshopify.com',
+      state: 'state',
+      isOnline: false,
+      scope: ['test_scope'].toString(),
+      accessToken: 'abcde-12345-123',
+    });
+
+    await storage.storeSession(session);
+
+    // Wait for the redis client to disconnect
+    await wait(2500);
+
+    const storedSession = await storage.loadSession(sessionId);
+    expect(storedSession).toBeDefined();
+    expect(storedSession?.id).toBe(sessionId);
+
+    await storage.disconnect();
+  });
 });
 
 async function initWithNonSessionData(client: RedisClient) {

packages/shopify-app-session-storage-redis/src/redis-connection.ts

@@ -7,18 +7,9 @@ export class RedisConnection implements DBConnection {
   sessionStorageIdentifier: string;
   private client: RedisClient;
 
-  constructor(
-    dbUrl: string,
-    options: RedisClientOptions,
-    keyPrefix: string,
-    onError?: (...args: any[]) => void,
-  ) {
+  constructor(dbUrl: string, options: RedisClientOptions, keyPrefix: string) {
     this.init(dbUrl, options);
     this.sessionStorageIdentifier = keyPrefix;
-
-    if (onError) {
-      this.client.on('error', onError);
-    }
   }
 
   query(_query: string, _params: any[]): Promise<any[]> {
@@ -62,5 +53,12 @@ export class RedisConnection implements DBConnection {
       ...options,
       url: dbUrl,
     });
+
+    this.client.on('error', this.eventHandler);
+    this.client.on('connect', this.eventHandler);
+    this.client.on('reconnecting', this.eventHandler);
+    this.client.on('ready', this.eventHandler);
   }
+
+  private eventHandler = (..._args: any[]) => {};
 }