public void ConvertCorrectly(string culture, string locale, string value, decimal expectedResult) { // Arrange CultureHelper.CurrentCulture = new CultureInfo(culture); CultureHelper.CurrentLocale = new CultureInfo(locale); Thread.CurrentThread.CurrentUICulture = CultureHelper.CurrentCulture; var converter = new DecimalConverter(); // Act decimal result = (decimal)converter.ConvertBack(value, null, null, Thread.CurrentThread.CurrentUICulture); // Assert result.Should().Be(expectedResult); }