1 files changed, 21 insertions, 0 deletions
diff --git a/spec/ruby/core/symbol/shared/id2name.rb b/spec/ruby/core/symbol/shared/id2name.rb
index 47f97bd332..00a9c7d7dc 100644
--- a/spec/ruby/core/symbol/shared/id2name.rb
+++ b/spec/ruby/core/symbol/shared/id2name.rb
@@ -6,4 +6,25 @@ describe :symbol_id2name, shared: true do
     :@ruby.send(@method).should == "@ruby"
     :@@ruby.send(@method).should == "@@ruby"
   end
+
+  it "returns a String in the same encoding as self" do
+    string = "ruby".encode("US-ASCII")
+    symbol = string.to_sym
+
+    symbol.send(@method).encoding.should == Encoding::US_ASCII
+  end
+
+  ruby_version_is "3.4" do
+    it "warns about mutating returned string" do
+      -> { :bad!.send(@method).upcase! }.should complain(/warning: string returned by :bad!.to_s will be frozen in the future/)
+    end
+
+    it "does not warn about mutation when Warning[:deprecated] is false" do
+      deprecated = Warning[:deprecated]
+      Warning[:deprecated] = false
+      -> { :bad!.send(@method).upcase! }.should_not complain
+    ensure
+      Warning[:deprecated] = deprecated
+    end
+  end
 end