Simple support for DUMP and RESTORE (#405)

* constants for key types

* shared logic for validating argument counts

* simple support for DUMP and RESTORE

* revert DebugDump rename

Author: alyssaruth

README.md

@@ -36,6 +36,7 @@ Implemented commands:
  - Key
    - COPY
    - DEL
+   - DUMP -- partly, only handles string keys
    - EXISTS
    - EXPIRE
    - EXPIREAT
@@ -50,6 +51,7 @@ Implemented commands:
    - RANDOMKEY -- see m.Seed(...)
    - RENAME
    - RENAMENX
+   - RESTORE -- partly, only handles string keys
    - SCAN
    - TOUCH
    - TTL
@@ -301,10 +303,8 @@ Commands which will probably not be implemented:
     - ~~READONLY~~
     - ~~READWRITE~~
  - Key
-    - ~~DUMP~~
     - ~~MIGRATE~~
     - ~~OBJECT~~
-    - ~~RESTORE~~
     - ~~WAIT~~
  - Scripting
     - ~~FCALL / FCALL_RO *~~

cmd_connection.go

@@ -213,12 +213,7 @@ func (m *Miniredis) cmdEcho(c *server.Peer, cmd string, args []string) {
 
 // SELECT
 func (m *Miniredis) cmdSelect(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.isValidCMD(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}