1 files changed, 11 insertions, 18 deletions
diff --git a/spec/ruby/core/string/upcase_spec.rb b/spec/ruby/core/string/upcase_spec.rb
index 6cf44b4703..652de5c2ef 100644
--- a/spec/ruby/core/string/upcase_spec.rb
+++ b/spec/ruby/core/string/upcase_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -8,6 +9,10 @@ describe "String#upcase" do
     "hello".upcase.should == "HELLO"
   end
 
+  it "returns a String in the same encoding as self" do
+    "hello".encode("US-ASCII").upcase.encoding.should == Encoding::US_ASCII
+  end
+
   describe "full Unicode case mapping" do
     it "works for all of Unicode with no option" do
       "äöü".upcase.should == "ÄÖÜ"
@@ -27,6 +32,10 @@ describe "String#upcase" do
     it "does not upcase non-ASCII characters" do
       "aßet".upcase(:ascii).should == "AßET"
     end
+
+    it "works with substrings" do
+      "prefix té"[-2..-1].upcase(:ascii).should == "Té"
+    end
   end
 
   describe "full Unicode case mapping adapted for Turkic languages" do
@@ -65,24 +74,8 @@ describe "String#upcase" do
     -> { "abc".upcase(:invalid_option) }.should raise_error(ArgumentError)
   end
 
-  ruby_version_is ''...'2.7' do
-    it "taints result when self is tainted" do
-      "".taint.upcase.should.tainted?
-      "X".taint.upcase.should.tainted?
-      "x".taint.upcase.should.tainted?
-    end
-  end
-
-  ruby_version_is ''...'3.0' do
-    it "returns a subclass instance for subclasses" do
-      StringSpecs::MyString.new("fooBAR").upcase.should be_an_instance_of(StringSpecs::MyString)
-    end
-  end
-
-  ruby_version_is '3.0' do
-    it "returns a String instance for subclasses" do
-      StringSpecs::MyString.new("fooBAR").upcase.should be_an_instance_of(String)
-    end
+  it "returns a String instance for subclasses" do
+    StringSpecs::MyString.new("fooBAR").upcase.should be_an_instance_of(String)
   end
 end