Make Future respond_to :class and :is_a? so that code given a potenti…

…ally futuristic value from Redis can figure out if it is a Future or not.

lib/redis/pipeline.rb

@@ -126,5 +126,13 @@ def value
       ::Kernel.raise(@object) if @object.kind_of?(::RuntimeError)
       @object
     end
+
+    def is_a?(other)
+      self.class.ancestors.include?(other)
+    end
+
+    def class
+      Future
+    end
   end
 end

test/pipelining_commands_test.rb

@@ -132,6 +132,18 @@ def test_futures_raise_when_trying_to_access_their_values_too_early
     end
   end
 
+  def test_futures_can_be_identified
+    r.pipelined do
+      @result = r.sadd("foo", 1)
+    end
+
+    assert_equal true, @result.is_a?(Redis::Future)
+    if defined?(::BasicObject)
+      assert_equal true, @result.is_a?(::BasicObject)
+    end
+    assert_equal Redis::Future, @result.class
+  end
+
   def test_returning_the_result_of_an_empty_pipeline
     result = r.pipelined do
     end