public void SubtractMonths_WhenSubtractingMonths_ReturnNewInstance()
{
// Arrange
var date = new DuodecimDate(2018, 6);
// Act
var newDate = date.SubtractMonths(1);
// Assert
Assert.False(Equals(date, newDate));
}
public void SubtractMonths_WhenSubtractingMonths_MonthsSubtracted()
{
// Arrange
const int startMonth = 8;
const int monthsToSubtract = 3;
const int expectedMonth = startMonth - monthsToSubtract;
var date = new DuodecimDate(2018, startMonth);
// Act
var newDate = date.SubtractMonths(monthsToSubtract);
// Assert
Assert.Equal(expectedMonth, newDate.Month);
}
SubtractMonths_WhenSubtractingMonthsSoTheResultYieldsAnInvalidDate_ThrowInvalidDuodecimDateException()
{
// Arrange
const int startYear = 1;
const int startMonth = 6;
const int monthsToSubtract = startMonth + 1;
const int expectedErrorMessageYear = 0;
const int expectedErrorMessageMonth = 11;
var date = new DuodecimDate(startYear, startMonth);
// Act
var exception = Record.Exception(() => date.SubtractMonths(monthsToSubtract));
// Assert
exception.Verify <InvalidDuodecimDateException>(string.Format(ExpectedInvalidDuodecimDateExceptionMessage,
expectedErrorMessageYear, expectedErrorMessageMonth));
}
SubtractMonths_WhenMonthAndSunbtracteddMonthExceedMonthsInYear_OneYearSubtractedAndExpectedNewMonthSet()
{
// Arrange
const int totalMonthsInYear = 12;
const int startyear = 2018;
const int startMonth = 1;
const int monthsToSubtract = 1;
const int expectedYear = startyear - 1;
const int expectedMonth = totalMonthsInYear + startMonth - monthsToSubtract;
var date = new DuodecimDate(startyear, startMonth);
// Act
var newDate = date.SubtractMonths(monthsToSubtract);
// Assert
Assert.Equal(expectedMonth, newDate.Month);
Assert.Equal(expectedYear, newDate.Year);
}
public void SubtractMonths_WhenSubtractingMoreMonthsThanExistInAYear_YearAndMonthsSubtracted()
{
// Arrange
const int totalMonthsInYear = 12;
const int startyear = 2018;
const int startMonth = 10;
const int monthsToSubtract = 29;
const int expectedYear = 2016;
const int expectedMonth = startMonth - (monthsToSubtract % totalMonthsInYear);
var date = new DuodecimDate(startyear, startMonth);
// Act
var newDate = date.SubtractMonths(monthsToSubtract);
// Assert
Assert.Equal(expectedMonth, newDate.Month);
Assert.Equal(expectedYear, newDate.Year);
}