add support for all set commands (including sScanIterator)

lib/commands/SMEMBERS.spec.ts

@@ -0,0 +1,19 @@
+import { strict as assert } from 'assert';
+import { TestRedisServers, itWithClient } from '../test-utils';
+import { transformArguments } from './SMEMBERS';
+
+describe('SMEMBERS', () => {
+    it('transformArguments', () => {
+        assert.deepEqual(
+            transformArguments('key'),
+            ['SMEMBERS', 'key']
+        );
+    });
+
+    itWithClient(TestRedisServers.OPEN, 'client.sMembers', async client => {
+        assert.deepEqual(
+            await client.sMembers('key'),
+            []
+        );
+    });
+});