accept sentinel options even with string keys

Before, the sentinel options were assumed to have symbol keys, so string keys
were ignored. This is surprising, as other Redis options can be indifferently
passed as symbols or strings. Now string keys are allowed too.

lib/redis/client.rb

@@ -22,7 +22,9 @@ class Client
       :reconnect_attempts => 1,
       :reconnect_delay => 0,
       :reconnect_delay_max => 0.5,
-      :inherit_socket => false
+      :inherit_socket => false,
+      :sentinels => nil,
+      :role => nil
     }
 
     attr_reader :options
@@ -89,7 +91,7 @@ def initialize(options = {})
       @pending_reads = 0
 
       @connector =
-        if options.include?(:sentinels)
+        if !@options[:sentinels].nil?
           Connector::Sentinel.new(@options)
         elsif options.include?(:connector) && options[:connector].respond_to?(:new)
           options.delete(:connector).new(@options)
@@ -539,7 +541,7 @@ def initialize(options)
           @options[:db] = DEFAULTS.fetch(:db)
 
           @sentinels = @options.delete(:sentinels).dup
-          @role = @options.fetch(:role, "master").to_s
+          @role = (@options[:role] || "master").to_s
           @master = @options[:host]
         end
 
@@ -576,10 +578,10 @@ def resolve
         def sentinel_detect
           @sentinels.each do |sentinel|
             client = Client.new(@options.merge({
-              :host => sentinel[:host],
-              :port => sentinel[:port],
-              password: sentinel[:password],
-              :reconnect_attempts => 0,
+              host: sentinel[:host] || sentinel["host"],
+              port: sentinel[:port] || sentinel["port"],
+              password: sentinel[:password] || sentinel["password"],
+              reconnect_attempts: 0
             }))
 
             begin

test/sentinel_test.rb

@@ -346,4 +346,35 @@ def test_sentinel_retries
 
     assert_match(/No sentinels available/, ex.message)
   end
+
+  def test_sentinel_with_string_option_keys
+    commands = []
+
+    master = {
+      role: lambda do
+        ['master']
+      end
+    }
+
+    sentinel = lambda do |port|
+      {
+        sentinel: lambda do |command, *args|
+          commands << [command, *args]
+          ['127.0.0.1', port.to_s]
+        end
+      }
+    end
+
+    RedisMock.start(master) do |master_port|
+      RedisMock.start(sentinel.call(master_port)) do |sen_port|
+        sentinels = [{ 'host' => '127.0.0.1', 'port' => sen_port }]
+
+        redis = Redis.new(url: 'redis://master1', 'sentinels' => sentinels, 'role' => :master)
+
+        assert redis.ping
+      end
+    end
+
+    assert_equal [%w[get-master-addr-by-name master1]], commands
+  end
 end