1 files changed, 29 insertions, 0 deletions
diff --git a/test/-ext-/string/test_set_len.rb b/test/-ext-/string/test_set_len.rb
index 67ba961194..e3eff75d9b 100644
--- a/test/-ext-/string/test_set_len.rb
+++ b/test/-ext-/string/test_set_len.rb
@@ -34,4 +34,33 @@ class Test_StrSetLen < Test::Unit::TestCase
     assert_equal 128, Bug::String.capacity(str)
     assert_equal 127, str.set_len(127).bytesize, bug12757
   end
+
+  def test_coderange_after_append
+    u = -"\u3042"
+    str = Bug::String.new(encoding: Encoding::UTF_8)
+    bsize = u.bytesize
+    str.append(u)
+    assert_equal 0, str.bytesize
+    str.set_len(bsize)
+    assert_equal bsize, str.bytesize
+    assert_predicate str, :valid_encoding?
+    assert_not_predicate str, :ascii_only?
+    assert_equal u, str
+  end
+
+  def test_coderange_after_trunc
+    u = -"\u3042"
+    bsize = u.bytesize
+    str = Bug::String.new(u)
+    str.set_len(bsize - 1)
+    assert_equal bsize - 1, str.bytesize
+    assert_not_predicate str, :valid_encoding?
+    assert_not_predicate str, :ascii_only?
+    str.append(u.byteslice(-1))
+    str.set_len(bsize)
+    assert_equal bsize, str.bytesize
+    assert_predicate str, :valid_encoding?
+    assert_not_predicate str, :ascii_only?
+    assert_equal u, str
+  end
 end