fix(client): handle ACL GETUSER null reply for nonexistent users

packages/client/lib/commands/ACL_GETUSER.spec.ts

@@ -13,6 +13,13 @@ describe('ACL GETUSER', () => {
     );
   });
 
+  it('transformReply passes a null reply through for nonexistent users', () => {
+    assert.equal(
+      (ACL_GETUSER.transformReply[2] as unknown as (reply: unknown) => unknown)(null),
+      null
+    );
+  });
+
   testUtils.testWithClient('client.aclGetUser', async client => {
     const reply = await client.aclGetUser('default');
 

packages/client/lib/commands/ACL_GETUSER.ts

@@ -1,5 +1,6 @@
 import { CommandParser } from '../client/parser';
-import { RedisArgument, TuplesToMapReply, BlobStringReply, ArrayReply, UnwrapReply, Resp2Reply, Command } from '../RESP/types';
+import { RedisArgument, TuplesToMapReply, BlobStringReply, ArrayReply, UnwrapReply, Resp2Reply, Command, NullReply } from '../RESP/types';
+import { isNullReply } from './generic-transformers';
 
 type AclUser = TuplesToMapReply<[
   [BlobStringReply<'flags'>, ArrayReply<BlobStringReply>],
@@ -23,21 +24,26 @@ export default {
     parser.push('ACL', 'GETUSER', username);
   },
   transformReply: {
-    2: (reply: UnwrapReply<Resp2Reply<AclUser>>) => ({
-      flags: reply[1],
-      passwords: reply[3],
-      commands: reply[5],
-      keys: reply[7],
-      channels: reply[9],
-      selectors: (reply[11] as unknown as UnwrapReply<typeof reply[11]>)?.map(selector => {
-        const inferred = selector as unknown as UnwrapReply<typeof selector>;
-        return {
-          commands: inferred[1],
-          keys: inferred[3],
-          channels: inferred[5]
-        };
-      })
-    }),
-    3: undefined as unknown as () => AclUser
+    // NullReply when the user does not exist
+    2: (reply: UnwrapReply<Resp2Reply<AclUser>> | NullReply) => {
+      if (isNullReply(reply)) return reply;
+
+      return {
+        flags: reply[1],
+        passwords: reply[3],
+        commands: reply[5],
+        keys: reply[7],
+        channels: reply[9],
+        selectors: (reply[11] as unknown as UnwrapReply<typeof reply[11]>)?.map(selector => {
+          const inferred = selector as unknown as UnwrapReply<typeof selector>;
+          return {
+            commands: inferred[1],
+            keys: inferred[3],
+            channels: inferred[5]
+          };
+        })
+      };
+    },
+    3: undefined as unknown as () => AclUser | NullReply
   }
 } as const satisfies Command;

packages/client/types-tests/acl-getuser.types-test.ts

@@ -0,0 +1,22 @@
+/**
+ * Compile-time regression for https://github.com/redis/node-redis/issues/2745.
+ *
+ * ACL GETUSER replies null for a nonexistent user, but the declared reply type
+ * claimed a non-null object shape and the RESP2 transformer indexed into the
+ * null reply. These assertions fail to compile against the unfixed code.
+ *
+ * Lives outside lib/ so it is not picked up by the production build / typedoc.
+ * Checked with `npm run test:types -w @redis/client`.
+ */
+import type { CommandReply, ReplyWithTypeMapping } from '../lib/RESP/types';
+import type ACL_GETUSER from '../lib/commands/ACL_GETUSER';
+
+type Assert<T extends true> = T;
+
+// The default (RESP3) client-facing reply type must include null.
+type Resp3ClientReply = ReplyWithTypeMapping<CommandReply<typeof ACL_GETUSER, 3>, {}>;
+export type Resp3ClientReplyIncludesNull = Assert<null extends Resp3ClientReply ? true : false>;
+
+// The RESP2 client-facing reply type must include null too.
+type Resp2ClientReply = ReplyWithTypeMapping<CommandReply<typeof ACL_GETUSER, 2>, {}>;
+export type Resp2ClientReplyIncludesNull = Assert<null extends Resp2ClientReply ? true : false>;