Support the NOVALUES option of HSCAN (#2711)

* Support the NOVALUES option of HSCAN

Issue #2705

The NOVALUES option instructs HSCAN to only return keys, without their
values. This is materialized as a new command, `hScanNoValues`, given
that the return type is different from the usual return type of `hScan`.
Also a new iterator is provided, `hScanNoValuesIterator`, for the same
reason.

* skip hscan novalues test if redis < 7.4

* Also don't test hscan no values iterator < 7.4

---------

Co-authored-by: Shaya Potter <spotter@gmail.com>

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

@@ -73,5 +73,18 @@ describe('HSCAN', () => {
                 tuples: []
             }
         );
+
+        await Promise.all([
+            client.hSet('key', 'a', '1'),
+            client.hSet('key', 'b', '2')
+        ]);
+
+        assert.deepEqual(
+            await client.hScan('key', 0),
+            {
+                cursor: 0,
+                tuples: [{field: 'a', value: '1'}, {field: 'b', value: '2'}]
+            }
+        );
     }, GLOBAL.SERVERS.OPEN);
 });

packages/client/lib/commands/HSCAN.ts

@@ -16,7 +16,7 @@ export function transformArguments(
     ], cursor, options);
 }
 
-type HScanRawReply = [RedisCommandArgument, Array<RedisCommandArgument>];
+export type HScanRawReply = [RedisCommandArgument, Array<RedisCommandArgument>];
 
 export interface HScanTuple {
     field: RedisCommandArgument;

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

@@ -0,0 +1,79 @@
+import { strict as assert } from 'assert';
+import testUtils, { GLOBAL } from '../test-utils';
+import { transformArguments, transformReply } from './HSCAN_NOVALUES';
+
+describe('HSCAN_NOVALUES', () => {
+    testUtils.isVersionGreaterThanHook([7, 4]);
+    
+    describe('transformArguments', () => {
+        it('cusror only', () => {
+            assert.deepEqual(
+                transformArguments('key', 0),
+                ['HSCAN', 'key', '0', 'NOVALUES']
+            );
+        });
+
+        it('with MATCH', () => {
+            assert.deepEqual(
+                transformArguments('key', 0, {
+                    MATCH: 'pattern'
+                }),
+                ['HSCAN', 'key', '0', 'MATCH', 'pattern', 'NOVALUES']
+            );
+        });
+
+        it('with COUNT', () => {
+            assert.deepEqual(
+                transformArguments('key', 0, {
+                    COUNT: 1
+                }),
+                ['HSCAN', 'key', '0', 'COUNT', '1', 'NOVALUES']
+            );
+        });
+    });
+
+    describe('transformReply', () => {
+        it('without keys', () => {
+            assert.deepEqual(
+                transformReply(['0', []]),
+                {
+                    cursor: 0,
+                    keys: []
+                }
+            );
+        });
+
+        it('with keys', () => {
+            assert.deepEqual(
+                transformReply(['0', ['key1', 'key2']]),
+                {
+                    cursor: 0,
+                    keys: ['key1', 'key2']
+                }
+            );
+        });
+    });
+
+    testUtils.testWithClient('client.hScanNoValues', async client => {
+        assert.deepEqual(
+            await client.hScanNoValues('key', 0),
+            {
+                cursor: 0,
+                keys: []
+            }
+        );
+
+        await Promise.all([
+            client.hSet('key', 'a', '1'),
+            client.hSet('key', 'b', '2')
+        ]);
+
+        assert.deepEqual(
+            await client.hScanNoValues('key', 0),
+            {
+                cursor: 0,
+                keys: ['a', 'b']
+            }
+        );
+    }, GLOBAL.SERVERS.OPEN);
+});

packages/client/lib/commands/HSCAN_NOVALUES.ts

@@ -0,0 +1,27 @@
+import { RedisCommandArgument, RedisCommandArguments } from '.';
+import { ScanOptions } from './generic-transformers';
+import { HScanRawReply, transformArguments as transformHScanArguments } from './HSCAN';
+
+export { FIRST_KEY_INDEX, IS_READ_ONLY } from './HSCAN';
+
+export function transformArguments(
+    key: RedisCommandArgument,
+    cursor: number,
+    options?: ScanOptions
+): RedisCommandArguments {
+    const args = transformHScanArguments(key, cursor, options);
+    args.push('NOVALUES');
+    return args;
+}
+
+interface HScanNoValuesReply {
+    cursor: number;
+    keys: Array<RedisCommandArgument>;
+}
+
+export function transformReply([cursor, rawData]: HScanRawReply): HScanNoValuesReply {
+    return {
+        cursor: Number(cursor),
+        keys: [...rawData]
+    };
+}