Fix `Symbol#size` for multi-byte characters with `MRB_UTF8_STRING`

Before:

  p :あ.size  #=> 3

After:

  p :あ.size  #=> 1

1 files changed, 12 insertions, 3 deletions

diff --git a/mrbgems/mruby-symbol-ext/test/symbol.rb b/mrbgems/mruby-symbol-ext/test/symbol.rb
index 63c1bd826..2c7a62b0c 100644
--- a/mrbgems/mruby-symbol-ext/test/symbol.rb
+++ b/mrbgems/mruby-symbol-ext/test/symbol.rb
@@ -7,9 +7,18 @@ assert('Symbol.all_symbols') do
   assert_equal foo, symbols
 end
 
-assert("Symbol#length") do
-  assert_equal 5, :hello.size
-  assert_equal 5, :mruby.length
+%w[size length].each do |n|
+  assert("Symbol##{n}") do
+    assert_equal 5, :hello.__send__(n)
+    assert_equal 4, :"aA\0b".__send__(n)
+    if "あ".size == 1  # enable MRB_UTF8_STRING?
+      assert_equal 8, :"こんにちは世界!".__send__(n)
+      assert_equal 4, :"aあ\0b".__send__(n)
+    else
+      assert_equal 22, :"こんにちは世界!".__send__(n)
+      assert_equal 6, :"aあ\0b".__send__(n)
+    end
+  end
 end
 
 assert("Symbol#capitalize") do