Fixed slice! behavior: return nil for out-of-bound parameters

2 files changed, 6 insertions, 1 deletions

diff --git a/activesupport/lib/active_support/multibyte/chars.rb b/activesupport/lib/active_support/multibyte/chars.rb
index f6a2e7e949..a76692ec4b 100644
--- a/activesupport/lib/active_support/multibyte/chars.rb
+++ b/activesupport/lib/active_support/multibyte/chars.rb
@@ -94,7 +94,8 @@ module ActiveSupport #:nodoc:
       #   string.mb_chars.slice!(0..3) # => #<ActiveSupport::Multibyte::Chars:0x00000002eb80a0 @wrapped_string="Welo">
       #   string # => 'me'
       def slice!(*args)
-        chars(@wrapped_string.slice!(*args))
+        string_sliced = @wrapped_string.slice!(*args)
+        string_sliced ? chars(string_sliced) : nil
       end
 
       # Reverses all characters in the string.
diff --git a/activesupport/test/multibyte_chars_test.rb b/activesupport/test/multibyte_chars_test.rb
index e1c4b705f8..42829c6a8e 100644
--- a/activesupport/test/multibyte_chars_test.rb
+++ b/activesupport/test/multibyte_chars_test.rb
@@ -413,6 +413,10 @@ class MultibyteCharsUTF8BehaviourTest < ActiveSupport::TestCase
     assert_equal 'にち', @chars.slice!(1..2)
   end
 
+  def test_slice_bang_returns_nil_on_out_of_bound_arguments
+    assert_equal nil, @chars.mb_chars.slice!(9..10)
+  end
+
   def test_slice_bang_removes_the_slice_from_the_receiver
     chars = 'úüù'.mb_chars
     chars.slice!(0,2)