Add spec for Date#next_day (#463)
Add spec for Date#next_day (#463)


ruby/spec,sgarciac/spec,ruby/spec,sgarciac/spec,sgarciac/spec,eregon/rubyspec,ruby/rubyspec,ruby/spec,nobu/rubyspec,ruby/rubyspec,nobu/rubyspec,eregon/rubyspec,eregon/rubyspec,nobu/rubyspec