Add tests for u_unpack to make sure it raises an EncodingError on invalid UTF-8 strings.

activesupport/lib/active_support/multibyte/chars.rb

@@ -446,7 +446,7 @@ module ActiveSupport #:nodoc:
           begin
             string.unpack 'U*'
           rescue ArgumentError
-            raise EncodingError.new('malformed UTF-8 character')
+            raise EncodingError, 'malformed UTF-8 character'
           end
         end
 

activesupport/test/multibyte_chars_test.rb

@@ -82,6 +82,17 @@ class MultibyteCharsTest < Test::Unit::TestCase
     assert !@proxy_class.consumes?(BYTE_STRING)
   end
 
+  def test_unpack_utf8_strings
+    assert_equal 4, @proxy_class.u_unpack(UNICODE_STRING).length
+    assert_equal 5, @proxy_class.u_unpack(ASCII_STRING).length
+  end
+
+  def test_unpack_raises_encoding_error_on_broken_strings
+    assert_raises(ActiveSupport::Multibyte::EncodingError) do
+      @proxy_class.u_unpack(BYTE_STRING)
+    end
+  end
+
   if RUBY_VERSION < '1.9'
     def test_concatenation_should_return_a_proxy_class_instance
       assert_equal ActiveSupport::Multibyte.proxy_class, ('a'.mb_chars + 'b').class