fiscalQuarter method
Returns the fiscal quarter (1–4) given a fiscal year start month.
DateTime(2024, 4, 1).fiscalQuarter(4) // 1 (fiscal year starts April)
DateTime(2024, 7, 1).fiscalQuarter(4) // 2
Implementation
int fiscalQuarter(int fiscalYearStartMonth) {
assert(fiscalYearStartMonth >= 1 && fiscalYearStartMonth <= 12,
'fiscalYearStartMonth must be 1–12');
final adjusted = (month - fiscalYearStartMonth + 12) % 12;
return adjusted ~/ 3 + 1;
}