1 files changed, 38 insertions, 2 deletions
diff --git a/spec/ruby/core/string/scrub_spec.rb b/spec/ruby/core/string/scrub_spec.rb
index 5c67ad01bc..b9ef0f1a16 100644
--- a/spec/ruby/core/string/scrub_spec.rb
+++ b/spec/ruby/core/string/scrub_spec.rb
@@ -1,5 +1,7 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "String#scrub with a default replacement" do
   it "returns self for valid strings" do
@@ -13,18 +15,33 @@ describe "String#scrub with a default replacement" do
     "abc\u3042#{x81}".scrub.should == "abc\u3042\uFFFD"
   end
 
+  it "replaces invalid byte sequences in lazy substrings" do
+    x81 = [0x81].pack('C').force_encoding('utf-8')
+    "abc\u3042#{x81}def"[1...-1].scrub.should == "bc\u3042\uFFFDde"
+  end
+
   it "returns a copy of self when the input encoding is BINARY" do
     input = "foo".encode('BINARY')
 
     input.scrub.should == "foo"
   end
 
-
   it "replaces invalid byte sequences when using ASCII as the input encoding" do
     xE3x80 = [0xE3, 0x80].pack('CC').force_encoding 'utf-8'
     input = "abc\u3042#{xE3x80}".force_encoding('ASCII')
     input.scrub.should == "abc?????"
   end
+
+  it "returns a String in the same encoding as self" do
+    x81 = [0x81].pack('C').force_encoding('utf-8')
+    "abc\u3042#{x81}".scrub.encoding.should == Encoding::UTF_8
+  end
+
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("foo").scrub.should be_an_instance_of(String)
+    input = [0x81].pack('C').force_encoding('utf-8')
+    StringSpecs::MyString.new(input).scrub.should be_an_instance_of(String)
+  end
 end
 
 describe "String#scrub with a custom replacement" do
@@ -42,7 +59,9 @@ describe "String#scrub with a custom replacement" do
   it "replaces invalid byte sequences in frozen strings" do
     x81 = [0x81].pack('C').force_encoding('utf-8')
     (-"abc\u3042#{x81}").scrub("*").should == "abc\u3042*"
-    utf16_str = ("abc".encode('UTF-16LE').bytes + [0x81]).pack('c*').force_encoding('UTF-16LE')
+
+    leading_surrogate = [0x00, 0xD8]
+    utf16_str = ("abc".encode('UTF-16LE').bytes + leading_surrogate).pack('c*').force_encoding('UTF-16LE')
     (-(utf16_str)).scrub("*".encode('UTF-16LE')).should == "abc*".encode('UTF-16LE')
   end
 
@@ -59,12 +78,23 @@ describe "String#scrub with a custom replacement" do
     block.should raise_error(ArgumentError)
   end
 
+  it "returns a String in the same encoding as self" do
+    x81 = [0x81].pack('C').force_encoding('utf-8')
+    "abc\u3042#{x81}".scrub("*").encoding.should == Encoding::UTF_8
+  end
+
   it "raises TypeError when a non String replacement is given" do
     x81 = [0x81].pack('C').force_encoding('utf-8')
     block = -> { "foo#{x81}".scrub(1) }
 
     block.should raise_error(TypeError)
   end
+
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("foo").scrub("*").should be_an_instance_of(String)
+    input = [0x81].pack('C').force_encoding('utf-8')
+    StringSpecs::MyString.new(input).scrub("*").should be_an_instance_of(String)
+  end
 end
 
 describe "String#scrub with a block" do
@@ -89,6 +119,12 @@ describe "String#scrub with a block" do
 
     replaced.should == "€€"
   end
+
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("foo").scrub { |b| "*" }.should be_an_instance_of(String)
+    input = [0x81].pack('C').force_encoding('utf-8')
+    StringSpecs::MyString.new(input).scrub { |b| "<#{b.unpack("H*")[0]}>" }.should be_an_instance_of(String)
+  end
 end
 
 describe "String#scrub!" do