From c76ba839b153805f0498229284fea1a809308dbc Mon Sep 17 00:00:00 2001
From: Shugo Maeda <shugo@ruby-lang.org>
Date: Thu, 11 Dec 2025 17:34:57 +0900
Subject: Allow String#strip etc. to take optional character selectors

[Feature #21552]

Co-Authored-By: Claude <noreply@anthropic.com>
---
 test/ruby/test_string.rb | 111 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)

(limited to 'test/ruby')

diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index 1fe0629331..7227f903c7 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -2049,6 +2049,117 @@ CODE
     assert_equal(S("x") ,a)
   end
 
+  def test_strip_with_selectors
+    assert_equal(S("abc"), S("---abc+++").strip("-+"))
+    assert_equal(S("abc"), S("+++abc---").strip("-+"))
+    assert_equal(S("abc"), S("+-+abc-+-").strip("-+"))
+    assert_equal(S(""), S("---+++").strip("-+"))
+    assert_equal(S("abc   "), S("---abc   ").strip("-"))
+    assert_equal(S("   abc"), S("   abc+++").strip("+"))
+
+    # Test with multibyte characters
+    assert_equal(S("abc"), S("あああabcいいい").strip("あい"))
+    assert_equal(S("abc"), S("いいいabcあああ").strip("あい"))
+
+    # Test with NUL characters
+    assert_equal(S("abc\0"), S("---abc\0--").strip("-"))
+    assert_equal(S("\0abc"), S("--\0abc---").strip("-"))
+
+    # Test without modification
+    assert_equal(S("abc"), S("abc").strip("-+"))
+    assert_equal(S("abc"), S("abc").strip(""))
+
+    # Test with range
+    assert_equal(S("abc"), S("012abc345").strip("0-9"))
+    assert_equal(S("abc"), S("012abc345").strip("^a-z"))
+
+    # Test with multiple selectors
+    assert_equal(S("4abc56"), S("01234abc56789").strip("0-9", "^4-6"))
+  end
+
+  def test_strip_bang_with_chars
+    a = S("---abc+++")
+    assert_equal(S("abc"), a.strip!("-+"))
+    assert_equal(S("abc"), a)
+
+    a = S("+++abc---")
+    assert_equal(S("abc"), a.strip!("-+"))
+    assert_equal(S("abc"), a)
+
+    a = S("abc")
+    assert_nil(a.strip!("-+"))
+    assert_equal(S("abc"), a)
+
+    # Test with multibyte characters
+    a = S("あああabcいいい")
+    assert_equal(S("abc"), a.strip!("あい"))
+    assert_equal(S("abc"), a)
+  end
+
+  def test_lstrip_with_selectors
+    assert_equal(S("abc+++"), S("---abc+++").lstrip("-"))
+    assert_equal(S("abc---"), S("+++abc---").lstrip("+"))
+    assert_equal(S("abc"), S("---abc").lstrip("-"))
+    assert_equal(S(""), S("---").lstrip("-"))
+
+    # Test with multibyte characters
+    assert_equal(S("abcいいい"), S("あああabcいいい").lstrip("あ"))
+
+    # Test with NUL characters
+    assert_equal(S("\0abc+++"), S("--\0abc+++").lstrip("-"))
+
+    # Test without modification
+    assert_equal(S("abc"), S("abc").lstrip("-"))
+
+    # Test with range
+    assert_equal(S("abc345"), S("012abc345").lstrip("0-9"))
+
+    # Test with multiple selectors
+    assert_equal(S("4abc56789"), S("01234abc56789").lstrip("0-9", "^4-6"))
+  end
+
+  def test_lstrip_bang_with_chars
+    a = S("---abc+++")
+    assert_equal(S("abc+++"), a.lstrip!("-"))
+    assert_equal(S("abc+++"), a)
+
+    a = S("abc")
+    assert_nil(a.lstrip!("-"))
+    assert_equal(S("abc"), a)
+  end
+
+  def test_rstrip_with_selectors
+    assert_equal(S("---abc"), S("---abc+++").rstrip("+"))
+    assert_equal(S("+++abc"), S("+++abc---").rstrip("-"))
+    assert_equal(S("abc"), S("abc+++").rstrip("+"))
+    assert_equal(S(""), S("+++").rstrip("+"))
+
+    # Test with multibyte characters
+    assert_equal(S("あああabc"), S("あああabcいいい").rstrip("い"))
+
+    # Test with NUL characters
+    assert_equal(S("---abc\0"), S("---abc\0++").rstrip("+"))
+
+    # Test without modification
+    assert_equal(S("abc"), S("abc").rstrip("-"))
+
+    # Test with range
+    assert_equal(S("012abc"), S("012abc345").rstrip("0-9"))
+
+    # Test with multiple selectors
+    assert_equal(S("01234abc56"), S("01234abc56789").rstrip("0-9", "^4-6"))
+  end
+
+  def test_rstrip_bang_with_chars
+    a = S("---abc+++")
+    assert_equal(S("---abc"), a.rstrip!("+"))
+    assert_equal(S("---abc"), a)
+
+    a = S("abc")
+    assert_nil(a.rstrip!("+"))
+    assert_equal(S("abc"), a)
+  end
+
   def test_sub
     assert_equal(S("h*llo"),    S("hello").sub(/[aeiou]/, S('*')))
     assert_equal(S("h<e>llo"),  S("hello").sub(/([aeiou])/, S('<\1>')))
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