From 637067440f74043c6d79fc649ab8acf1afea25a5 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Mon, 30 Sep 2024 16:24:03 +0900
Subject: [Bug #20752] Slice of readonly `IO::Buffer` also should be readonly

---
 test/ruby/test_io_buffer.rb | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'test/ruby/test_io_buffer.rb')

diff --git a/test/ruby/test_io_buffer.rb b/test/ruby/test_io_buffer.rb
index 7a58ec0c5a..7087a2b957 100644
--- a/test/ruby/test_io_buffer.rb
+++ b/test/ruby/test_io_buffer.rb
@@ -236,6 +236,18 @@ class TestIOBuffer < Test::Unit::TestCase
     end
   end
 
+  def test_slice_readonly
+    hello = %w"Hello World".join(" ").freeze
+    buffer = IO::Buffer.for(hello)
+    slice = buffer.slice
+    assert_predicate slice, :readonly?
+    assert_raise IO::Buffer::AccessError do
+      # This breaks the literal in string pool and many other tests in this file.
+      slice.set_string("Adios", 0, 5)
+    end
+    assert_equal "Hello World", hello
+  end
+
   def test_locked
     buffer = IO::Buffer.new(128, IO::Buffer::INTERNAL|IO::Buffer::LOCKED)
 
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