1 files changed, 25 insertions, 18 deletions
diff --git a/spec/ruby/language/singleton_class_spec.rb b/spec/ruby/language/singleton_class_spec.rb
index 7e9370d6f9..45e1f7f3ad 100644
--- a/spec/ruby/language/singleton_class_spec.rb
+++ b/spec/ruby/language/singleton_class_spec.rb
@@ -70,7 +70,7 @@ describe "A singleton class" do
   end
 
   it "has class String as the superclass of a String instance" do
-    "blah".singleton_class.superclass.should == String
+    "blah".dup.singleton_class.superclass.should == String
   end
 
   it "doesn't have singleton class" do
@@ -157,23 +157,6 @@ describe "A constant on a singleton class" do
   end
 end
 
-describe "Defining yield in singleton class" do
-  ruby_version_is "2.7"..."3.0" do
-    it 'emits a deprecation warning' do
-      code = <<~RUBY
-          def m
-            class << Object.new
-              yield
-            end
-          end
-          m { :ok }
-        RUBY
-
-      -> { eval(code) }.should complain(/warning: `yield' in class syntax will not be supported from Ruby 3.0/)
-    end
-  end
-end
-
 describe "Defining instance methods on a singleton class" do
   before :each do
     @k = ClassSpecs::K.new
@@ -308,3 +291,27 @@ describe "Instantiating a singleton class" do
     }.should raise_error(TypeError)
   end
 end
+
+describe "Frozen properties" do
+  it "is frozen if the object it is created from is frozen" do
+    o = Object.new
+    o.freeze
+    klass = o.singleton_class
+    klass.frozen?.should == true
+  end
+
+  it "will be frozen if the object it is created from becomes frozen" do
+    o = Object.new
+    klass = o.singleton_class
+    klass.frozen?.should == false
+    o.freeze
+    klass.frozen?.should == true
+  end
+
+  it "will be unfrozen if the frozen object is cloned with freeze set to false" do
+    o = Object.new
+    o.freeze
+    o2 = o.clone(freeze: false)
+    o2.singleton_class.frozen?.should == false
+  end
+end