1 files changed, 45 insertions, 8 deletions
diff --git a/spec/ruby/core/string/rstrip_spec.rb b/spec/ruby/core/string/rstrip_spec.rb
index a1453f91fe..6d46eb590e 100644
--- a/spec/ruby/core/string/rstrip_spec.rb
+++ b/spec/ruby/core/string/rstrip_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/strip'
@@ -11,18 +12,18 @@ describe "String#rstrip" do
     "  hello world \n\r\t\n\v\r".rstrip.should == "  hello world"
     "hello".rstrip.should == "hello"
     "hello\x00".rstrip.should == "hello"
+    "こにちわ ".rstrip.should == "こにちわ"
   end
 
-  it "returns a copy of self with all trailing whitespace and NULL bytes removed" do
-    "\x00 \x00hello\x00 \x00".rstrip.should == "\x00 \x00hello"
+  it "works with lazy substrings" do
+    "  hello  "[1...-1].rstrip.should == " hello"
+    "  hello world  "[1...-1].rstrip.should == " hello world"
+    "  hello world \n\r\t\n\v\r"[1...-1].rstrip.should == " hello world"
+    " こにちわ  "[1...-1].rstrip.should == "こにちわ"
   end
 
-  ruby_version_is ''...'2.7' do
-    it "taints the result when self is tainted" do
-      "".taint.rstrip.should.tainted?
-      "ok".taint.rstrip.should.tainted?
-      "ok    ".taint.rstrip.should.tainted?
-    end
+  it "returns a copy of self with all trailing whitespace and NULL bytes removed" do
+    "\x00 \x00hello\x00 \x00".rstrip.should == "\x00 \x00hello"
   end
 end
 
@@ -45,6 +46,18 @@ describe "String#rstrip!" do
     a.should == "hello"
   end
 
+  it "makes a string empty if it is only whitespace" do
+    "".rstrip!.should == nil
+    " ".rstrip.should == ""
+    "  ".rstrip.should == ""
+  end
+
+  it "removes trailing NULL bytes and whitespace" do
+    a = "\000 goodbye \000"
+    a.rstrip!
+    a.should == "\000 goodbye"
+  end
+
   it "raises a FrozenError on a frozen instance that is modified" do
     -> { "  hello  ".freeze.rstrip! }.should raise_error(FrozenError)
   end
@@ -54,4 +67,28 @@ describe "String#rstrip!" do
     -> { "hello".freeze.rstrip! }.should raise_error(FrozenError)
     -> { "".freeze.rstrip!      }.should raise_error(FrozenError)
   end
+
+  ruby_version_is "3.2" do
+    it "raises an Encoding::CompatibilityError if the last non-space codepoint is invalid" do
+      s = "abc\xDF".force_encoding(Encoding::UTF_8)
+      s.valid_encoding?.should be_false
+      -> { s.rstrip! }.should raise_error(Encoding::CompatibilityError)
+
+      s = "abc\xDF   ".force_encoding(Encoding::UTF_8)
+      s.valid_encoding?.should be_false
+      -> { s.rstrip! }.should raise_error(Encoding::CompatibilityError)
+    end
+  end
+
+  ruby_version_is ""..."3.2" do
+    it "raises an ArgumentError if the last non-space codepoint is invalid" do
+      s = "abc\xDF".force_encoding(Encoding::UTF_8)
+      s.valid_encoding?.should be_false
+      -> { s.rstrip! }.should raise_error(ArgumentError)
+
+      s = "abc\xDF   ".force_encoding(Encoding::UTF_8)
+      s.valid_encoding?.should be_false
+      -> { s.rstrip! }.should raise_error(ArgumentError)
+    end
+  end
 end