Re-implement RedisClient::Cluster#multi in terms of #with

This does change the behaviour ever so slightly (see updated tests), but
I believe for the better.

Author: KJ Tsanaktsidis

lib/redis_client/cluster.rb

@@ -5,7 +5,6 @@
 require 'redis_client/cluster/pipeline'
 require 'redis_client/cluster/pub_sub'
 require 'redis_client/cluster/router'
-require 'redis_client/cluster/transaction'
 
 class RedisClient
   class Cluster
@@ -90,8 +89,14 @@ def pipelined
       pipeline.execute
     end
 
-    def multi(watch: nil, &block)
-      ::RedisClient::Cluster::Transaction.new(@router, @command_builder).execute(watch: watch, &block)
+    def multi(watch: nil, key: nil, &block)
+      slot_key = key
+      slot_key = watch&.first if slot_key.nil?
+      raise ArgumentError, 'watch or key must be provided' if slot_key.nil?
+
+      with(key: slot_key) do |conn|
+        conn.multi(watch: watch, &block)
+      end
     end
 
     def pubsub

lib/redis_client/cluster/errors.rb

@@ -57,5 +57,9 @@ def initialize(_ = '')
     end
 
     class BlockingReadTimeoutError < ::RedisClient::ReadTimeoutError; end
+
+    module Transaction
+      ConsistencyError = Class.new(::RedisClient::Error)
+    end
   end
 end

lib/redis_client/cluster/transaction.rb

@@ -178,7 +178,7 @@ def test_pipelined_with_many_commands
       end
 
       def test_transaction_with_single_key
-        got = @client.multi do |t|
+        got = @client.multi(key: 'counter') do |t|
           t.call('SET', 'counter', '0')
           t.call('INCR', 'counter')
           t.call('INCR', 'counter')
@@ -190,7 +190,7 @@ def test_transaction_with_single_key
 
       def test_transaction_with_multiple_key
         assert_raises(::RedisClient::Cluster::Transaction::ConsistencyError) do
-          @client.multi do |t|
+          @client.multi(key: 'key1') do |t|
             t.call('SET', 'key1', '1')
             t.call('SET', 'key2', '2')
             t.call('SET', 'key3', '3')
@@ -204,20 +204,19 @@ def test_transaction_with_multiple_key
 
       def test_transaction_with_empty_block
         assert_raises(ArgumentError) { @client.multi {} }
-        assert_raises(LocalJumpError) { @client.multi }
+        assert_raises(LocalJumpError) { @client.multi(key: 'foo') }
       end
 
       def test_transaction_with_keyless_commands
-        assert_raises(::RedisClient::Cluster::Transaction::ConsistencyError) do
-          @client.multi do |t|
-            t.call('ECHO', 'foo')
-            t.call('ECHO', 'bar')
-          end
+        got = @client.multi(key: 'hello') do |t|
+          t.call('ECHO', 'foo')
+          t.call('ECHO', 'bar')
         end
+        assert_equal %w[foo bar], got
       end
 
       def test_transaction_with_hashtag
-        got = @client.multi do |t|
+        got = @client.multi(key: '{key}') do |t|
           t.call('MSET', '{key}1', '1', '{key}2', '2')
           t.call('MSET', '{key}3', '3', '{key}4', '4')
         end
@@ -228,14 +227,14 @@ def test_transaction_with_hashtag
 
       def test_transaction_without_hashtag
         assert_raises(::RedisClient::Cluster::Transaction::ConsistencyError) do
-          @client.multi do |t|
+          @client.multi(key: 'key1') do |t|
             t.call('MSET', 'key1', '1', 'key2', '2')
             t.call('MSET', 'key3', '3', 'key4', '4')
           end
         end
 
-        assert_raises(::RedisClient::CommandError, 'CROSSSLOT keys') do
-          @client.multi do |t|
+        assert_raises(::RedisClient::Cluster::Transaction::ConsistencyError) do
+          @client.multi(key: 'key1') do |t|
             t.call('MSET', 'key1', '1', 'key2', '2')
             t.call('MSET', 'key1', '1', 'key3', '3')
             t.call('MSET', 'key1', '1', 'key4', '4')