Update to ruby/spec@4f59d86

1 files changed, 13 insertions, 0 deletions

diff --git a/spec/ruby/core/integer/chr_spec.rb b/spec/ruby/core/integer/chr_spec.rb
index a8755eeb84..9f105e4241 100644
--- a/spec/ruby/core/integer/chr_spec.rb
+++ b/spec/ruby/core/integer/chr_spec.rb
@@ -240,4 +240,17 @@ describe "Integer#chr with an encoding argument" do
       -> { integer.chr(encoding_name) }.should raise_error(RangeError)
     end
   end
+
+  ruby_version_is "2.7" do
+    it 'returns a String encoding self interpreted as a codepoint in the CESU-8 encoding' do
+      # see more details here https://en.wikipedia.org/wiki/CESU-8
+      # code points from U+0000 to U+FFFF is encoded in the same way as in UTF-8
+      0x0045.chr(Encoding::CESU_8).bytes.should == 0x0045.chr(Encoding::UTF_8).bytes
+
+      # code points in range from U+10000 to U+10FFFF is CESU-8 data containing a 6-byte surrogate pair,
+      # which decodes to a 4-byte UTF-8 string
+      0x10400.chr(Encoding::CESU_8).bytes.should != 0x10400.chr(Encoding::UTF_8).bytes
+      0x10400.chr(Encoding::CESU_8).bytes.to_a.should == [0xED, 0xA0, 0x81, 0xED, 0xB0, 0x80]
+    end
+  end
 end