diff --git a/spec/mongoid/enum_spec.rb b/spec/mongoid/enum_spec.rb
index e551df2..4139e1d 100644
--- a/spec/mongoid/enum_spec.rb
+++ b/spec/mongoid/enum_spec.rb
@@ -68,6 +68,22 @@ describe Mongoid::Enum do
     end
   end
 
+  describe "'required' option" do
+    context "when true" do
+      let(:instance) { User.new status: nil }
+      it "is not valid with nil value" do
+        expect(instance).to_not be_valid
+      end
+    end
+
+    context "when false" do
+      let(:instance) { User.new roles: nil }
+      it "is valid with nil value" do
+        expect(instance).to be_valid
+      end
+    end
+  end
+
   describe "constant" do
     it "is set to the values" do
       expect(klass::STATUS).to eq values