System.Globalization.GregorianCalendar.IsLeapMonth C# (CSharp) Method

        public override bool IsLeapMonth(int year, int month, int era)
        {
            if (era != CurrentEra && era != ADEra) {
                throw new ArgumentOutOfRangeException("era", Environment.GetResourceString("ArgumentOutOfRange_InvalidEraValue"));
            }

            if (year < 1 || year > MaxYear) {
                throw new ArgumentOutOfRangeException(
                            "year",
                            String.Format(
                                CultureInfo.CurrentCulture,
                                Environment.GetResourceString("ArgumentOutOfRange_Range"), 1, MaxYear));
            }

            if (month < 1 || month > 12) {
                throw new ArgumentOutOfRangeException("month", String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("ArgumentOutOfRange_Range"),
                    1, 12));
            }
            return (false);

        }

 public void PosTest4()
 {
     System.Globalization.Calendar myCalendar = new GregorianCalendar(GregorianCalendarTypes.USEnglish);
     int year, month;
     bool expectedValue;
     bool actualValue;
     year = myCalendar.MaxSupportedDateTime.Year;
     month = _generator.GetInt32(-55) % 12 + 1;
     expectedValue = false;
     actualValue = myCalendar.IsLeapMonth(year, month, 1);
     Assert.Equal(expectedValue, actualValue);
 }