7 files changed, 51 insertions, 0 deletions
diff --git a/spec/ruby/core/matchdata/captures_spec.rb b/spec/ruby/core/matchdata/captures_spec.rb
index 8c0d2978b7..58d4620709 100644
--- a/spec/ruby/core/matchdata/captures_spec.rb
+++ b/spec/ruby/core/matchdata/captures_spec.rb
@@ -1,7 +1,15 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#captures" do
   it "returns an array of the match captures" do
     /(.)(.)(\d+)(\d)/.match("THX1138.").captures.should == ["H","X","113","8"]
   end
+
+  ruby_version_is "3.0" do
+    it "returns instances of String when given a String subclass" do
+      str = MatchDataSpecs::MyString.new("THX1138: The Movie")
+      /(.)(.)(\d+)(\d)/.match(str).captures.each { |c| c.should be_an_instance_of(String) }
+    end
+  end
 end
diff --git a/spec/ruby/core/matchdata/element_reference_spec.rb b/spec/ruby/core/matchdata/element_reference_spec.rb
index 26550ac94d..3b976cb1c4 100644
--- a/spec/ruby/core/matchdata/element_reference_spec.rb
+++ b/spec/ruby/core/matchdata/element_reference_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#[]" do
   it "acts as normal array indexing [index]" do
@@ -20,6 +21,13 @@ describe "MatchData#[]" do
   it "supports ranges [start..end]" do
     /(.)(.)(\d+)(\d)/.match("THX1138.")[1..3].should == %w|H X 113|
   end
+
+  ruby_version_is "3.0" do
+    it "returns instances of String when given a String subclass" do
+      str = MatchDataSpecs::MyString.new("THX1138.")
+      /(.)(.)(\d+)(\d)/.match(str)[0..-1].each { |m| m.should be_an_instance_of(String) }
+    end
+  end
 end
 
 describe "MatchData#[Symbol]" do
diff --git a/spec/ruby/core/matchdata/fixtures/classes.rb b/spec/ruby/core/matchdata/fixtures/classes.rb
new file mode 100644
index 0000000000..54795636e5
--- /dev/null
+++ b/spec/ruby/core/matchdata/fixtures/classes.rb
@@ -0,0 +1,3 @@
+module MatchDataSpecs
+  class MyString < String; end
+end
diff --git a/spec/ruby/core/matchdata/post_match_spec.rb b/spec/ruby/core/matchdata/post_match_spec.rb
index 4ae51f107e..1a4ca0a83f 100644
--- a/spec/ruby/core/matchdata/post_match_spec.rb
+++ b/spec/ruby/core/matchdata/post_match_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#post_match" do
   it "returns the string after the match equiv. special var $'" do
@@ -33,4 +34,11 @@ describe "MatchData#post_match" do
     str = "abc".force_encoding Encoding::ISO_8859_1
     str.match(/c/).post_match.encoding.should equal(Encoding::ISO_8859_1)
   end
+
+  ruby_version_is "3.0" do
+    it "returns an instance of String when given a String subclass" do
+      str = MatchDataSpecs::MyString.new("THX1138: The Movie")
+      /(.)(.)(\d+)(\d)/.match(str).post_match.should be_an_instance_of(String)
+    end
+  end
 end
diff --git a/spec/ruby/core/matchdata/pre_match_spec.rb b/spec/ruby/core/matchdata/pre_match_spec.rb
index 824612c84c..9b50336c7d 100644
--- a/spec/ruby/core/matchdata/pre_match_spec.rb
+++ b/spec/ruby/core/matchdata/pre_match_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#pre_match" do
   it "returns the string before the match, equiv. special var $`" do
@@ -33,4 +34,11 @@ describe "MatchData#pre_match" do
     str = "abc".force_encoding Encoding::ISO_8859_1
     str.match(/a/).pre_match.encoding.should equal(Encoding::ISO_8859_1)
   end
+
+  ruby_version_is "3.0" do
+    it "returns an instance of String when given a String subclass" do
+      str = MatchDataSpecs::MyString.new("THX1138: The Movie")
+      /(.)(.)(\d+)(\d)/.match(str).pre_match.should be_an_instance_of(String)
+    end
+  end
 end
diff --git a/spec/ruby/core/matchdata/to_a_spec.rb b/spec/ruby/core/matchdata/to_a_spec.rb
index 6231d096fb..50f5a161a5 100644
--- a/spec/ruby/core/matchdata/to_a_spec.rb
+++ b/spec/ruby/core/matchdata/to_a_spec.rb
@@ -1,7 +1,15 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#to_a" do
   it "returns an array of matches" do
     /(.)(.)(\d+)(\d)/.match("THX1138.").to_a.should == ["HX1138", "H", "X", "113", "8"]
   end
+
+  ruby_version_is "3.0" do
+    it "returns instances of String when given a String subclass" do
+      str = MatchDataSpecs::MyString.new("THX1138.")
+      /(.)(.)(\d+)(\d)/.match(str)[0..-1].to_a.each { |m| m.should be_an_instance_of(String) }
+    end
+  end
 end
diff --git a/spec/ruby/core/matchdata/to_s_spec.rb b/spec/ruby/core/matchdata/to_s_spec.rb
index 9e213bb342..aab0955ae1 100644
--- a/spec/ruby/core/matchdata/to_s_spec.rb
+++ b/spec/ruby/core/matchdata/to_s_spec.rb
@@ -1,7 +1,15 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#to_s" do
   it "returns the entire matched string" do
     /(.)(.)(\d+)(\d)/.match("THX1138.").to_s.should == "HX1138"
   end
+
+  ruby_version_is "3.0" do
+    it "returns an instance of String when given a String subclass" do
+      str = MatchDataSpecs::MyString.new("THX1138.")
+      /(.)(.)(\d+)(\d)/.match(str).to_s.should be_an_instance_of(String)
+    end
+  end
 end