Add US federal holidays

holidays_us.go

@@ -0,0 +1,45 @@
+package holidays
+
+import "time"
+
+func init() {
+	registerHolidayDataSource("us", holidaysUSNational{})
+}
+
+type holidaysUSNational struct{}
+
+func (h holidaysUSNational) GetIncludes() []string { return []string{} }
+func (h holidaysUSNational) GetHolidays(year int) []Holiday {
+	return []Holiday{
+		newHoliday("New Year's Day", map[string]string{}, h.fixWeekend(dateFromNumbers(year, 1, 1))),                                         // 1st January
+		newHoliday("Birthday of Martin Luther King, Jr.", map[string]string{}, h.findNextWeekday(dateFromNumbers(year, 1, 15), time.Monday)), // Third Monday in January
+		newHoliday("Washington's Birthday", map[string]string{}, h.findNextWeekday(dateFromNumbers(year, 2, 15), time.Monday)),               // Third Monday in February
+		newHoliday("Memorial Day", map[string]string{}, h.findNextWeekday(dateFromNumbers(year, 5, 25), time.Monday)),                        // Last Monday in May
+		newHoliday("Independence Day", map[string]string{}, h.fixWeekend(dateFromNumbers(year, 7, 4))),                                       // 4 July
+		newHoliday("Labor Day", map[string]string{}, h.findNextWeekday(dateFromNumbers(year, 9, 1), time.Monday)),                            // First Monday in September
+		newHoliday("Columbus Day", map[string]string{}, h.findNextWeekday(dateFromNumbers(year, 10, 8), time.Monday)),                        // Second Monday in October
+		newHoliday("Veterans Day", map[string]string{}, h.fixWeekend(dateFromNumbers(year, 11, 11))),                                         // 11 November
+		newHoliday("Thanksgiving Day", map[string]string{}, h.findNextWeekday(dateFromNumbers(year, 11, 23), time.Thursday)),                 // Fourth Thursday in November
+		newHoliday("Christmas Day", map[string]string{}, h.fixWeekend(dateFromNumbers(year, 12, 25))),                                        // 25 December
+	}
+}
+
+func (h holidaysUSNational) findNextWeekday(in time.Time, wd time.Weekday) time.Time {
+	for in.Weekday() != wd {
+		in = in.Add(1 * 24 * time.Hour)
+	}
+	return in
+}
+
+// If a holiday falls on a Saturday it is celebrated the preceding Friday;
+// if a holiday falls on a Sunday it is celebrated the following Monday.
+func (h holidaysUSNational) fixWeekend(in time.Time) time.Time {
+	switch in.Weekday() {
+	case time.Saturday:
+		return in.Add(-1 * 24 * time.Hour)
+	case time.Sunday:
+		return in.Add(1 * 24 * time.Hour)
+	default:
+		return in
+	}
+}

holidays_us_test.go

@@ -0,0 +1,71 @@
+package holidays
+
+import (
+	"testing"
+	"time"
+)
+
+func TestHolidaysUS(t *testing.T) {
+	// List of known dates according to US Office of Personnel Management
+	// https://www.opm.gov/policy-data-oversight/snow-dismissal-procedures/federal-holidays/
+
+	knownDates := map[int]map[string]time.Time{
+		2011: map[string]time.Time{
+			"New Year's Day":                      dateFromNumbers(2010, 12, 31), // 1 = Saturday... What the hell are you doing?!?
+			"Birthday of Martin Luther King, Jr.": dateFromNumbers(2011, 1, 17),
+			"Washington's Birthday":               dateFromNumbers(2011, 2, 21),
+			"Memorial Day":                        dateFromNumbers(2011, 5, 30),
+			"Independence Day":                    dateFromNumbers(2011, 7, 4),
+			"Labor Day":                           dateFromNumbers(2011, 9, 5),
+			"Columbus Day":                        dateFromNumbers(2011, 10, 10),
+			"Veterans Day":                        dateFromNumbers(2011, 11, 11),
+			"Thanksgiving Day":                    dateFromNumbers(2011, 11, 24),
+			"Christmas Day":                       dateFromNumbers(2011, 12, 26), // 25 = Sunday
+		},
+		2014: map[string]time.Time{
+			"New Year's Day":                      dateFromNumbers(2014, 1, 1),
+			"Birthday of Martin Luther King, Jr.": dateFromNumbers(2014, 1, 20),
+			"Washington's Birthday":               dateFromNumbers(2014, 2, 17),
+			"Memorial Day":                        dateFromNumbers(2014, 5, 26),
+			"Independence Day":                    dateFromNumbers(2014, 7, 4),
+			"Labor Day":                           dateFromNumbers(2014, 9, 1),
+			"Columbus Day":                        dateFromNumbers(2014, 10, 13),
+			"Veterans Day":                        dateFromNumbers(2014, 11, 11),
+			"Thanksgiving Day":                    dateFromNumbers(2014, 11, 27),
+			"Christmas Day":                       dateFromNumbers(2014, 12, 25),
+		},
+		2017: map[string]time.Time{
+			"New Year's Day":                      dateFromNumbers(2017, 1, 2), // 1 = Sunday
+			"Birthday of Martin Luther King, Jr.": dateFromNumbers(2017, 1, 16),
+			"Washington's Birthday":               dateFromNumbers(2017, 2, 20),
+			"Memorial Day":                        dateFromNumbers(2017, 5, 29),
+			"Independence Day":                    dateFromNumbers(2017, 7, 4),
+			"Labor Day":                           dateFromNumbers(2017, 9, 4),
+			"Columbus Day":                        dateFromNumbers(2017, 10, 9),
+			"Veterans Day":                        dateFromNumbers(2017, 11, 10), // 11 = Saturday
+			"Thanksgiving Day":                    dateFromNumbers(2017, 11, 23),
+			"Christmas Day":                       dateFromNumbers(2017, 12, 25),
+		},
+	}
+
+	for year, knownHolidays := range knownDates {
+		generatedHolidays, err := GetHolidays("us", year)
+		if err != nil {
+			t.Fatalf("[US] Could not load holidays for %d: %s", year, err)
+		}
+
+		for name, date := range knownHolidays {
+
+			found := false
+			for _, hd := range generatedHolidays {
+				if hd.Name == name && hd.ParsedDate == date {
+					found = true
+				}
+			}
+			if !found {
+				t.Errorf("[US] Did not find %q on %s.", name, date.Format("2006-01-02"))
+			}
+
+		}
+	}
+}