diff --git a/code/__HELPERS/time.dm b/code/__HELPERS/time.dm
index 9edb40bfd03..9c57f2334c8 100644
--- a/code/__HELPERS/time.dm
+++ b/code/__HELPERS/time.dm
@@ -59,17 +59,38 @@ GLOBAL_VAR_INIT(rollovercheck_last_timeofday, 0)
 		if (SUNDAY)
 			return 7
 
-///Returns the first day of the given year and month in number format, from 1 (monday) - 7 (sunday).
-/proc/first_day_of_month(year, month)
+///Returns an integer in ISO format 1 (Monday) - 7 (Sunday) as a string day
+/proc/iso_to_weekday(ddd)
+	switch (ddd)
+		if (1)
+			return MONDAY
+		if (2)
+			return TUESDAY
+		if (3)
+			return WEDNESDAY
+		if (4)
+			return THURSDAY
+		if (5)
+			return FRIDAY
+		if (6)
+			return SATURDAY
+		if (7)
+			return SUNDAY
+
+/// Returns the day (mon, tues, wen...) in number format, 1 (monday) - 7 (sunday) from the passed in date (year, month, day)
+/// All inputs are expected indexed at 1
+/proc/day_of_month(year, month, day)
 	// https://en.wikipedia.org/wiki/Zeller%27s_congruence
 	var/m = month < 3 ? month + 12 : month // month (march = 3, april = 4...february = 14)
 	var/K = year % 100 // year of century
 	var/J = round(year / 100) // zero-based century
-	// day 0-6 saturday to sunday:
-	var/h = (1 + round(13 * (m + 1) / 5) + K + round(K / 4) + round(J / 4) - 2 * J) % 7
+	// day 0-6 saturday to friday:
+	var/h = (day + round(13 * (m + 1) / 5) + K + round(K / 4) + round(J / 4) - 2 * J) % 7
 	//convert to ISO 1-7 monday first format
 	return ((h + 5) % 7) + 1
 
+/proc/first_day_of_month(year, month)
+	return day_of_month(year, month, 1)
 
 //Takes a value of time in deciseconds.
 //Returns a text value of that number in hours, minutes, or seconds.
diff --git a/code/modules/holiday/holidays.dm b/code/modules/holiday/holidays.dm
index dddb1dd30cc..aed67f1bba9 100644
--- a/code/modules/holiday/holidays.dm
+++ b/code/modules/holiday/holidays.dm
@@ -794,3 +794,20 @@
 
 /datum/holiday/easter/getStationPrefix()
 	return pick("Fluffy","Bunny","Easter","Egg")
+
+/// Takes a holiday datum, a starting month, ending month, max amount of days to test in, and min/max year as input
+/// Returns a list in the form list("yyyy/m/d", ...) representing all days the holiday runs on in the tested range
+/proc/poll_holiday(datum/holiday/path, min_month, max_month, min_year, max_year, max_day)
+	var/list/deets = list()
+	for(var/year in min_year to max_year)
+		for(var/month in min_month to max_month)
+			for(var/day in 1 to max_day)
+				var/datum/holiday/new_day = new path()
+				if(new_day.shouldCelebrate(day, month, year, iso_to_weekday(day_of_month(year, month, day))))
+					deets += "[year]/[month]/[day]"
+	return deets
+
+/// Does the same as [/proc/poll_holiday], but prints the output to admins instead of returning it
+/proc/print_holiday(datum/holiday/path, min_month, max_month, min_year, max_year, max_day)
+	var/list/deets = poll_holiday(path, min_month, max_month, min_year, max_year, max_day)
+	message_admins("The accepted dates for [path] in the input range [min_year]-[max_year]/[min_month]-[max_month]/1-[max_day] are [deets.Join("\n")]")
diff --git a/code/modules/unit_tests/holidays.dm b/code/modules/unit_tests/holidays.dm
index b1b1d5c82f1..ce48c4e1d7d 100644
--- a/code/modules/unit_tests/holidays.dm
+++ b/code/modules/unit_tests/holidays.dm
@@ -29,8 +29,20 @@
 	TEST_ASSERT(new_year.shouldCelebrate(2, JANUARY, 1983, SUNDAY), "January 2, 1983 was not New Year.")
 
 /datum/unit_test/moth_week_2020/Run()
-	var/datum/holiday/nth_week/moth/moth = new
-	TEST_ASSERT(moth.shouldCelebrate(18, JULY, 2020, SATURDAY), "July 18, 2020 was not Moth Week.")
-	TEST_ASSERT(moth.shouldCelebrate(20, JULY, 2020, MONDAY), "July 20, 2020 was not Moth Week.")
-	TEST_ASSERT(moth.shouldCelebrate(24, JULY, 2020, FRIDAY), "July 24, 2020 was not Moth Week.")
-	TEST_ASSERT(moth.shouldCelebrate(26, JULY, 2020, SUNDAY), "July 26, 2020 was not Moth Week.")
+	// We expect 2 year's worth of moth week, falling on the last full week of july
+	// We test ahead and behind just in case something's fucked
+	// Both lists are in the form yyyy/m/d
+	var/list/produced_moth_days = poll_holiday(/datum/holiday/nth_week/moth, 6, 8, 2020, 2021, 31)
+	var/list/predicted_moth_days = list()
+	for(var/day in 18 to 26) // Last full week of July 2020
+		predicted_moth_days += "2020/7/[day]"
+	for(var/day in 17 to 25) // Last full week of July 2021
+		predicted_moth_days += "2021/7/[day]"
+	var/list/unexpected_moths = produced_moth_days - predicted_moth_days
+	for(var/date in unexpected_moths)
+		TEST_FAIL("[date] was improperly Moth Week")
+
+	var/list/missing_moths = predicted_moth_days - produced_moth_days
+	for(var/date in missing_moths)
+		TEST_FAIL("[date] was not Moth Week")
+