EN_NZHolidayStrategy: added Matariki and fixed 2011 Easter-Anzac clash

src/DateTimeExtensions/WorkingDays/CultureStrategies/EN_NZHolidayStrategy.cs

@@ -23,6 +23,7 @@ public EN_NZHolidayStrategy()
             this.InnerHolidays.Add(ChristianHolidays.EasterMonday);
             this.InnerHolidays.Add(AnzacDay);
             this.InnerHolidays.Add(QueensBirthday);
+            this.InnerHolidays.Add(Matariki);
             this.InnerHolidays.Add(LabourDay);
             this.InnerHolidays.Add(ChristianHolidays.Christmas);
             this.InnerHolidays.Add(GlobalHolidays.BoxingDay);
@@ -36,7 +37,18 @@ protected override IDictionary<DateTime, Holiday> BuildObservancesMap(int year)
                 var date = innerHoliday.GetInstance(year);
                 if (date.HasValue)
                 {
-                    holidayMap.Add(date.Value, innerHoliday);
+                    // If the holiday already exists in the map, combine the two holidays.
+                    // This is apparent for Easter Monday/Anzac Day on 25 April 2011.
+                    if (holidayMap.TryGetValue(date.Value, out var existingHoliday))
+                    {
+                        var combinedHoliday = new FixedHoliday($"{existingHoliday.Name}/{innerHoliday.Name}", 
+                            date.Value.Month, date.Value.Day);
+                        holidayMap[date.Value] = combinedHoliday;
+                    }
+                    else
+                    {
+                        holidayMap.Add(date.Value, innerHoliday);
+                    }
 
                     // New Year, Day After New Year, Christmas and Boxing Days are 'Mondayised'
                     // ie if these dates fall on a weekday then they are observed on the actual day.
@@ -148,6 +160,42 @@ public static Holiday QueensBirthday
             }
         }
 
+        // Some Friday on June or July - Matariki
+        private static Holiday matariki;
+        private static Holiday Matariki
+        {
+            get
+            {
+                if (matariki == null)
+                {
+                    // Matariki doesn't have a readily-available algorithm and its dates have been calulated up to
+                    // 2052 by the Matariki Advisory Committee.
+                    // See https://www.mbie.govt.nz/assets/matariki-dates-2022-to-2052-matariki-advisory-group.pdf
+
+                    var knownMatarikiOccurences = new Dictionary<int, DayInYear>
+                    {
+                        {2022, new DayInYear(6, 24)},
+                        {2023, new DayInYear(7, 14)},
+                        {2024, new DayInYear(6, 28)},
+                        {2025, new DayInYear(6, 20)},
+                        {2026, new DayInYear(7, 10)},
+                        {2027, new DayInYear(6, 25)},
+                        {2028, new DayInYear(7, 14)},
+                        {2029, new DayInYear(7, 6)},
+                        {2030, new DayInYear(6, 21)},
+                        {2031, new DayInYear(7, 11)},
+                        {2032, new DayInYear(7, 2)},
+                        {2033, new DayInYear(6, 24)},
+                        {2034, new DayInYear(7, 7)},
+                        {2035, new DayInYear(6, 29)}
+                    };
+
+                    matariki = new YearMapHoliday("Matariki", knownMatarikiOccurences);
+                }
+                return matariki;
+            }
+        }
+
         // 4th Monday in October - Labour Day
         private static Holiday labourDay;
 

tests/DateTimeExtensions.Tests/en-NZCalendarTest.cs

@@ -17,7 +17,11 @@ public void NewYearsDay()
         {
             var workingDayCultureInfo = new WorkingDayCultureInfo("en-NZ");
 
-            var dateOnGregorian = new DateTime(2013, 1, 1);
+            var dateOnGregorian = new DateTime(2011, 1, 1);
+            TestHoliday(workingDayCultureInfo, dateOnGregorian);
+            dateOnGregorian = new DateTime(2012, 1, 1);
+            TestHoliday(workingDayCultureInfo, dateOnGregorian);
+            dateOnGregorian = new DateTime(2013, 1, 1);
             TestHoliday(workingDayCultureInfo, dateOnGregorian);
             dateOnGregorian = new DateTime(2014, 1, 1);
             TestHoliday(workingDayCultureInfo, dateOnGregorian);
@@ -58,6 +62,54 @@ public void DayAfterNewYearsDay()
             TestHoliday(workingDayCultureInfo, dateOnGregorian);
         }
 
+        [Test]
+        public void EasterAnzacClash()
+        {
+            var workingDayCultureInfo = new WorkingDayCultureInfo("en-NZ");
+
+            var holidays = workingDayCultureInfo.GetHolidaysOfYear(2010);
+            Assert.IsTrue(holidays.Any(h => h.Name == "Easter Monday"));
+            Assert.IsTrue(holidays.Any(h => h.Name == "Anzac Day"));
+            Assert.IsFalse(holidays.Any(h => h.Name == "Easter Monday/Anzac Day"));
+
+            holidays = workingDayCultureInfo.GetHolidaysOfYear(2011);
+            Assert.IsFalse(holidays.Any(h => h.Name == "Easter Monday"));
+            Assert.IsFalse(holidays.Any(h => h.Name == "Anzac Day"));
+            Assert.IsTrue(holidays.Any(h => h.Name == "Easter Monday/Anzac Day"));
+
+            holidays = workingDayCultureInfo.GetHolidaysOfYear(2012);
+            Assert.IsTrue(holidays.Any(h => h.Name == "Easter Monday"));
+            Assert.IsTrue(holidays.Any(h => h.Name == "Anzac Day"));
+            Assert.IsFalse(holidays.Any(h => h.Name == "Easter Monday/Anzac Day"));
+
+            holidays = workingDayCultureInfo.GetHolidaysOfYear(2095);
+            Assert.IsFalse(holidays.Any(h => h.Name == "Easter Monday"));
+            Assert.IsFalse(holidays.Any(h => h.Name == "Anzac Day"));
+            Assert.IsTrue(holidays.Any(h => h.Name == "Easter Monday/Anzac Day"));
+        }
+
+        [Test]
+        public void Matariki()
+        {
+            var workingDayCultureInfo = new WorkingDayCultureInfo("en-NZ");
+
+            var dateOnGregorian = new DateTime(2022, 6, 24);
+            TestHoliday(workingDayCultureInfo, dateOnGregorian);
+            dateOnGregorian = new DateTime(2023, 7, 14);
+            TestHoliday(workingDayCultureInfo, dateOnGregorian);
+            dateOnGregorian = new DateTime(2024, 6, 28);
+            TestHoliday(workingDayCultureInfo, dateOnGregorian);
+            dateOnGregorian = new DateTime(2025, 6, 20);
+            TestHoliday(workingDayCultureInfo, dateOnGregorian);
+            dateOnGregorian = new DateTime(2026, 7, 10);
+
+
+            var holidays = workingDayCultureInfo.GetHolidaysOfYear(2021);
+            Assert.IsFalse(holidays.Any(h => h.Name == "Matariki"));
+            holidays = workingDayCultureInfo.GetHolidaysOfYear(2022);
+            Assert.IsTrue(holidays.Any(h => h.Name == "Matariki"));
+        }
+
         [Test]
         public void Christmas()
         {
@@ -105,6 +157,8 @@ public void BoxingDay()
         }
 
 
+
+
         private void TestHoliday(IWorkingDayCultureInfo workingDayCultureInfo, DateTime dateOnGregorian)
         {
             var isHoliday = workingDayCultureInfo.IsHoliday(dateOnGregorian);