[ioredis] improve scan() function types (#29451)

types/ioredis/index.d.ts

@@ -7,6 +7,7 @@
 //                 Shahar Mor <https://github.com/shaharmor>
 //                 Whemoon Jang <https://github.com/palindrom615>
 //                 Francis Gulotta <https://github.com/reconbot>
+//                 Dmitry Motovilov <https://github.com/funthing>
 //                 Oleg Repin <https://github.com/iamolegga>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.8
@@ -455,7 +456,13 @@ declare namespace IORedis {
         quit(callback: (err: Error, res: string) => void): void;
         quit(): Promise<string>;
 
-        scan(cursor: number, ...args: any[]): any;
+        scan(cursor: number): Promise<[string, string[]]>;
+
+        scan(cursor: number, matchOption: 'match' | 'MATCH', pattern: string): Promise<[string, string[]]>;
+        scan(cursor: number, countOption: 'count' | 'COUNT', count: number): Promise<[string, string[]]>;
+
+        scan(cursor: number, matchOption: 'match' | 'MATCH', pattern: string, countOption: 'count' | 'COUNT', count: number): Promise<[string, string[]]>;
+        scan(cursor: number, countOption: 'count' | 'COUNT', count: number, matchOption: 'match' | 'MATCH', pattern: string): Promise<[string, string[]]>;
 
         sscan(key: KeyType, cursor: number, ...args: any[]): any;
 
@@ -776,8 +783,13 @@ declare namespace IORedis {
 
         quit(callback?: (err: Error, res: string) => void): Pipeline;
 
-        scan(cursor: number, ...args: any[]): Pipeline;
+        scan(cursor: number): Pipeline;
 
+        scan(cursor: number, matchOption: 'match' | 'MATCH', pattern: string): Pipeline;
+        scan(cursor: number, countOption: 'count' | 'COUNT', count: number): Pipeline;
+
+        scan(cursor: number, matchOption: 'match' | 'MATCH', pattern: string, countOption: 'count' | 'COUNT', count: number): Pipeline;
+        scan(cursor: number, countOption: 'count' | 'COUNT', count: number, matchOption: 'match' | 'MATCH', pattern: string): Pipeline;
         sscan(key: KeyType, cursor: number, ...args: any[]): Pipeline;
 
         hscan(key: KeyType, cursor: number, ...args: any[]): Pipeline;

types/ioredis/ioredis-tests.ts

@@ -124,6 +124,18 @@ Redis.Command.setReplyTransformer('get', (result: any) => {
     return result;
 });
 
+redis.scan(0, 'match', '*foo*', 'count', 20).then(([nextCursor, keys]) => {
+  // nextCursor is always a string
+  if (nextCursor === '0') {
+    // keys is always an array of strings and it might be empty
+    return keys.map(key => key.trim());
+  }
+});
+
+redis.pipeline().scan(0, 'count', 20, 'match', '*foo*').exec((err, result) => {
+  // result = [[null, [nextCursor, keys]]]
+});
+
 // multi
 redis.multi().set('foo', 'bar').set('foo', 'baz').get('foo', (err, result) => {
     // result === 'QUEUED'