un-implent "SCAN COUNT" so cursors work as they should

Author: alicebob

cmd_generic.go

@@ -649,7 +649,8 @@ func (m *Miniredis) cmdScan(c *server.Peer, cmd string, args []string) {
 
 	withTx(m, c, func(c *server.Peer, ctx *connCtx) {
 		db := m.db(ctx.selectedDB)
-		// We return _all_ (matched) keys every time.
+		// We return _all_ (matched) keys every time, so that cursors work.
+		// We ignore "COUNT", which is allowed according to the Redis docs.
 		var keys []string
 
 		if opts.withType {
@@ -670,24 +671,27 @@ func (m *Miniredis) cmdScan(c *server.Peer, cmd string, args []string) {
 			keys, _ = matchKeys(keys, opts.match)
 		}
 
-		low := opts.cursor
-		high := low + opts.count
-		// validate high is correct
-		if high > len(keys) || high == 0 {
-			high = len(keys)
-		}
-		if opts.cursor > high {
-			// invalid cursor
-			c.WriteLen(2)
-			c.WriteBulk("0") // no next cursor
-			c.WriteLen(0)    // no elements
-			return
-		}
-		cursorValue := low + opts.count
-		if cursorValue >= len(keys) {
-			cursorValue = 0 // no next cursor
-		}
-		keys = keys[low:high]
+		cursorValue := 0 // we don't use cursors
+		/*
+			low := opts.cursor
+			high := low + opts.count
+			// validate high is correct
+			if high > len(keys) || high == 0 {
+				high = len(keys)
+			}
+			if opts.cursor > high {
+				// invalid cursor
+				c.WriteLen(2)
+				c.WriteBulk("0") // no next cursor
+				c.WriteLen(0)    // no elements
+				return
+			}
+			cursorValue := low + opts.count
+			if cursorValue >= len(keys) {
+				cursorValue = 0 // no next cursor
+			}
+			keys = keys[low:high]
+		*/
 
 		c.WriteLen(2)
 		c.WriteBulk(fmt.Sprintf("%d", cursorValue))