From 564ccd095a9d7fbe869031dbf666d61dadfdcb03 Mon Sep 17 00:00:00 2001
From: Kenichi Kamiya <kachick1@gmail.com>
Date: Wed, 31 Mar 2021 14:56:28 +0900
Subject: [ruby/strscan] Fix segmentation fault of `StringScanner#charpos` when
 `String#byteslice` returns non string value [Bug #17756] (#20)

https://github.com/ruby/strscan/commit/92961cde2b
---
 test/strscan/test_stringscanner.rb | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

(limited to 'test/strscan')

diff --git a/test/strscan/test_stringscanner.rb b/test/strscan/test_stringscanner.rb
index 4b001b317e..6e30be1f7d 100644
--- a/test/strscan/test_stringscanner.rb
+++ b/test/strscan/test_stringscanner.rb
@@ -206,6 +206,23 @@ class TestStringScanner < Test::Unit::TestCase
     assert_equal 11, s.charpos
   end
 
+  def test_charpos_not_use_string_methods
+    string = +'abcädeföghi'
+    scanner = create_string_scanner(string)
+
+    class << string
+      EnvUtil.suppress_warning do
+        undef_method(*instance_methods)
+      end
+    end
+
+    assert_equal 0, scanner.charpos
+    assert_equal "abcä", scanner.scan_until(/ä/)
+    assert_equal 4, scanner.charpos
+    assert_equal "defö", scanner.scan_until(/ö/)
+    assert_equal 8, scanner.charpos
+  end
+
   def test_concat
     s = create_string_scanner('a'.dup)
     s.scan(/a/)
-- 
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