1 files changed, 22 insertions, 0 deletions
diff --git a/test/stringio/test_stringio.rb b/test/stringio/test_stringio.rb
index aeccac2577..64bc5f67c3 100644
--- a/test/stringio/test_stringio.rb
+++ b/test/stringio/test_stringio.rb
@@ -842,6 +842,17 @@ class TestStringIO < Test::Unit::TestCase
     assert_match(/\Ab+\z/, s.string)
   end
 
+  def test_ungetc_same_string
+    s = StringIO.new("abc" * 30)
+    s.ungetc(s.string)
+    assert_match(/\A(?:abc){60}\z/, s.string)
+
+    s = StringIO.new("abc" * 30)
+    s.pos = 70 # ("abc".size * 30 - 70).divmod(3) == [6, 2]
+    s.ungetc(s.string)
+    assert_match(/\A(?:abc){30}bc(?:abc){6}\z/, s.string)
+  end
+
   def test_ungetbyte_pos
     b = '\\b00010001 \\B00010001 \\b1 \\B1 \\b000100011'
     s = StringIO.new( b )
@@ -876,6 +887,17 @@ class TestStringIO < Test::Unit::TestCase
     assert_match(/\Ab+\z/, s.string)
   end
 
+  def test_ungetbyte_same_string
+    s = StringIO.new("abc" * 30)
+    s.ungetc(s.string)
+    assert_match(/\A(?:abc){60}\z/, s.string)
+
+    s = StringIO.new("abc" * 30)
+    s.pos = 70 # ("abc".size * 30 - 70).divmod(3) == [6, 2]
+    s.ungetbyte(s.string)
+    assert_match(/\A(?:abc){30}bc(?:abc){6}\z/, s.string)
+  end
+
   def test_frozen
     s = StringIO.new
     s.freeze