Add rb_str_resize coderange test

2 files changed, 26 insertions, 0 deletions

diff --git a/ext/-test-/string/set_len.c b/ext/-test-/string/set_len.c
index 049da2cdb5..b55ef6f469 100644
--- a/ext/-test-/string/set_len.c
+++ b/ext/-test-/string/set_len.c
@@ -16,9 +16,17 @@ bug_str_append(VALUE str, VALUE addendum)
     return str;
 }
 
+static VALUE
+bug_str_resize(VALUE str, VALUE len)
+{
+    rb_str_resize(str, NUM2LONG(len));
+    return str;
+}
+
 void
 Init_string_set_len(VALUE klass)
 {
     rb_define_method(klass, "set_len", bug_str_set_len, 1);
     rb_define_method(klass, "append", bug_str_append, 1);
+    rb_define_method(klass, "resize", bug_str_resize, 1);
 }
diff --git a/test/-ext-/string/test_set_len.rb b/test/-ext-/string/test_set_len.rb
index e3eff75d9b..1531d76167 100644
--- a/test/-ext-/string/test_set_len.rb
+++ b/test/-ext-/string/test_set_len.rb
@@ -63,4 +63,22 @@ class Test_StrSetLen < Test::Unit::TestCase
     assert_not_predicate str, :ascii_only?
     assert_equal u, str
   end
+
+  def test_valid_encoding_after_resized
+    s = "\0\0".force_encoding(Encoding::UTF_16BE)
+    str = Bug::String.new(s)
+    assert_predicate str, :valid_encoding?
+    str.resize(1)
+    assert_not_predicate str, :valid_encoding?
+    str.resize(2)
+    assert_predicate str, :valid_encoding?
+    str.resize(3)
+    assert_not_predicate str, :valid_encoding?
+
+    s = "\xDB\x00\xDC\x00".force_encoding(Encoding::UTF_16BE)
+    str = Bug::String.new(s)
+    assert_predicate str, :valid_encoding?
+    str.resize(2)
+    assert_not_predicate str, :valid_encoding?
+  end
 end