fix #2398 - fix v4 interface in legacyMode (#2402)

packages/client/lib/client/index.spec.ts

@@ -2,7 +2,7 @@ import { strict as assert } from 'assert';
 import testUtils, { GLOBAL, waitTillBeenCalled } from '../test-utils';
 import RedisClient, { RedisClientType } from '.';
 import { RedisClientMultiCommandType } from './multi-command';
-import { RedisCommandArguments, RedisCommandRawReply, RedisModules, RedisFunctions, RedisScripts } from '../commands';
+import { RedisCommandRawReply, RedisModules, RedisFunctions, RedisScripts } from '../commands';
 import { AbortError, ClientClosedError, ClientOfflineError, ConnectionTimeoutError, DisconnectsClientError, SocketClosedUnexpectedlyError, WatchError } from '../errors';
 import { defineScript } from '../lua-script';
 import { spy } from 'sinon';
@@ -199,6 +199,18 @@ describe('Client', () => {
             }
         });
 
+        testUtils.testWithClient('client.v4.{command} should return a promise', async client => {
+            assert.equal(
+                await client.v4.ping(),
+                'PONG'
+            );
+        }, {
+            ...GLOBAL.SERVERS.OPEN,
+            clientOptions: {
+                legacyMode: true
+            }
+        });
+
         testUtils.testWithClient('client.{command} should accept vardict arguments', async client => {
             assert.equal(
                 await promisify(client.set).call(client, 'a', 'b'),

packages/client/lib/client/index.ts

@@ -352,7 +352,7 @@ export default class RedisClient<
 
         for (const [ name, command ] of Object.entries(COMMANDS as RedisCommands)) {
             this.#defineLegacyCommand(name, command);
-            (this as any)[name.toLowerCase()] = (this as any)[name];
+            (this as any)[name.toLowerCase()] ??= (this as any)[name];
         }
 
         // hard coded commands

packages/client/lib/client/multi-command.ts

@@ -119,7 +119,7 @@ export default class RedisClientMultiCommand {
 
         for (const [ name, command ] of Object.entries(COMMANDS as RedisCommands)) {
             this.#defineLegacyCommand(name, command);
-            (this as any)[name.toLowerCase()] = (this as any)[name];
+            (this as any)[name.toLowerCase()] ??= (this as any)[name];
         }
     }