Added specs for sentinel support

spec/fixtures/gitlab_config_redis.yml

+redis:
+  bin: /usr/bin/redis-cli
+  host: 127.0.1.1
+  port: 6378
+  pass: secure
+  database: 1
+  socket: /var/run/redis/redis.sock
+  namespace: my:gitlab
+  sentinels:
+    -
+      host: 127.0.0.1
+      port: 26380

spec/gitlab_config_spec.rb

@@ -6,17 +6,8 @@ describe GitlabConfig do
 
   describe :redis do
     before do
-      config.instance_variable_set(:@config, YAML.load(<<eos
-redis:
-  bin: /usr/bin/redis-cli
-  host: 127.0.1.1
-  port: 6378
-  pass: secure
-  database: 1
-  socket: /var/run/redis/redis.sock
-  namespace: my:gitlab
-eos
-                                   ))
+      config_file = File.read('spec/fixtures/gitlab_config_redis.yml')
+      config.instance_variable_set(:@config, YAML.load(config_file))
     end
 
     it { config.redis['bin'].should eq('/usr/bin/redis-cli') }
@@ -26,6 +17,7 @@ eos
     it { config.redis['namespace'].should eq('my:gitlab') }
     it { config.redis['socket'].should eq('/var/run/redis/redis.sock') }
     it { config.redis['pass'].should eq('secure') }
+    it { config.redis['sentinels'].should eq([{ 'host' => '127.0.0.1', 'port' => 26380 }]) }
   end
 
   describe :gitlab_url do

spec/gitlab_net_spec.rb

@@ -306,6 +306,20 @@ describe GitlabNet, vcr: true do
       end
     end
 
+    context "with sentinels" do
+      it 'users the specified sentinels' do
+        allow(gitlab_net).to receive(:config).and_return(config)
+        allow(config).to receive(:redis).and_return({ 'host' => 'localhost', 'port' => 1123,
+                                                      'sentinels' => [{'host' => '127.0.0.1', 'port' => 26380}] })
+
+        expect_any_instance_of(Redis).to receive(:initialize).with({ host: 'localhost',
+                                                                     port: 1123,
+                                                                     db: 0,
+                                                                     sentinels: [{host: '127.0.0.1', port: 26380}] }).and_call_original
+        gitlab_net.redis_client
+      end
+    end
+
 
     context "with redis socket" do
       let(:socket) { '/tmp/redis.socket' }