Add sample to set (#100)

Author: heka1024

lib/kredis/types/set.rb

@@ -1,5 +1,5 @@
 class Kredis::Types::Set < Kredis::Types::Proxying
-  proxying :smembers, :sadd, :srem, :multi, :del, :sismember, :scard, :spop, :exists?
+  proxying :smembers, :sadd, :srem, :multi, :del, :sismember, :scard, :spop, :exists?, :srandmember
 
   attr_accessor :typed
 
@@ -39,4 +39,12 @@ def take
   def clear
     del
   end
+
+  def sample(count = nil)
+    if count.nil?
+      string_to_type(srandmember(count), typed)
+    else
+      strings_to_types(srandmember(count), typed)
+    end
+  end
 end

test/types/set_test.rb

@@ -88,4 +88,12 @@ class SetTest < ActiveSupport::TestCase
     @set.add(%w[ 1 2 3 ])
     assert @set.exists?
   end
+
+  test "srandmember" do
+    @set = Kredis.set "mylist", typed: :float
+    @set.add 1.5, 2.7
+
+    assert @set.sample.in?([ 1.5, 2.7 ])
+    assert_equal [ 1.5, 2.7 ], @set.sample(2).sort
+  end
 end