def test_screen_name_with_valid_examples
  user = @valid_user
  valid_screen_names = %w{aure michael web_20}
  valid_screen_names.each do |screen_name|
    user.screen_name = screen_name
    assert user.valid?, "#{screen_name} powinien przej walidacj, a tak si nie dzieje."
  end
end

def test_screen_name_with_invalid_examples
  user = @valid_user
  invalid_screen_names = %w{rails/rocks web2.0 javscript:something}
  invalid_screen_names.each do |screen_name|
    user.screen_name = screen_name
    assert !user.valid?, "#{screen_name} nie powinien przej walidacji, a przechodzi."
  end
end

