1 files changed, 10 insertions, 0 deletions
diff --git a/spec/ruby/core/nil/to_s_spec.rb b/spec/ruby/core/nil/to_s_spec.rb
index c7a18e2527..4b61f589f7 100644
--- a/spec/ruby/core/nil/to_s_spec.rb
+++ b/spec/ruby/core/nil/to_s_spec.rb
@@ -4,4 +4,14 @@ describe "NilClass#to_s" do
   it "returns the string ''" do
     nil.to_s.should == ""
   end
+
+  ruby_version_is "2.7" do
+    it "returns a frozen string" do
+      nil.to_s.frozen?.should == true
+    end
+
+    it "always returns the same string" do
+      nil.to_s.should equal(nil.to_s)
+    end
+  end
 end