Check size in bytes as opposed to string size

- `size` returns length in characters, but doesn't factor in multibyte Unicode characters.
By switching to `bytesize`, we check the relevant measure of how many bytes the worksheet name is.
- Fixes https://github.com/randym/axlsx/issues/588
- Copy of PR against original axlsx
(https://github.com/randym/axlsx/pull/589)

2 files changed, 12 insertions, 1 deletions

diff --git a/lib/axlsx/workbook/worksheet/worksheet.rb b/lib/axlsx/workbook/worksheet/worksheet.rb
index 6fbd384e..9cfefa51 100644
--- a/lib/axlsx/workbook/worksheet/worksheet.rb
+++ b/lib/axlsx/workbook/worksheet/worksheet.rb
@@ -656,7 +656,7 @@ module Axlsx
 
     def validate_sheet_name(name)
       DataTypeValidator.validate :worksheet_name, String, name
-      raise ArgumentError, (ERR_SHEET_NAME_TOO_LONG % name) if name.size > 31
+      raise ArgumentError, (ERR_SHEET_NAME_TOO_LONG % name) if name.bytesize > 31
       raise ArgumentError, (ERR_SHEET_NAME_CHARACTER_FORBIDDEN % name) if '[]*/\?:'.chars.any? { |char| name.include? char }
       name = Axlsx::coder.encode(name)
       sheet_names = @workbook.worksheets.reject { |s| s == self }.map { |s| s.name }
diff --git a/test/workbook/worksheet/tc_worksheet.rb b/test/workbook/worksheet/tc_worksheet.rb
index fa8832d8..781f5250 100644
--- a/test/workbook/worksheet/tc_worksheet.rb
+++ b/test/workbook/worksheet/tc_worksheet.rb
@@ -29,6 +29,17 @@ class TestWorksheet < Test::Unit::TestCase
     assert_raises(ArgumentError) { @ws.name = 'foo?bar' }
   end
 
+  def test_exception_if_name_too_long
+    assert_nothing_raised { @ws.name = 'x' * 31 }
+    assert_raises(ArgumentError) { @ws.name = 'x' * 32 }
+  end
+
+  def test_exception_if_name_too_long_because_of_multibyte_characters
+    three_byte_character = "✔"
+    assert_nothing_raised { @ws.name = 'x' * 28 + three_byte_character}
+    assert_raises(ArgumentError) { @ws.name = 'x' * 29 + three_byte_character }
+  end
+
   def test_page_margins
     assert(@ws.page_margins.is_a? Axlsx::PageMargins)
   end