THRIFT-708. rb: Is set checking methods

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@911557 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/rb/spec/union_spec.rb b/lib/rb/spec/union_spec.rb
index f39d033..f563b0b 100644
--- a/lib/rb/spec/union_spec.rb
+++ b/lib/rb/spec/union_spec.rb
@@ -153,5 +153,12 @@
       
       My_union.new(:my_map => {SomeEnum::ONE => [SomeEnum::TWO]}).inspect.should == "<SpecNamespace::My_union my_map: {ONE (0): [TWO (1)]}>" 
     end
+    
+    it "should offer field? methods" do
+      My_union.new.some_enum?.should be_false
+      My_union.new(:some_enum => SomeEnum::ONE).some_enum?.should be_true
+      My_union.new(:im_true => false).im_true?.should be_true
+      My_union.new(:im_true => true).im_true?.should be_true
+    end
   end
 end