[Hotfix] Age check error

Personnummer.Tests/CoordinationNumberTests.cs

@@ -105,12 +105,17 @@ public void TestParseInvalidCn(PersonnummerData ssn)
         public void TestAgeCn(PersonnummerData ssn)
         {
             var timeProvider = new TestTimeProvider();
+            var localNow = timeProvider.GetLocalNow();
 
             int day = int.Parse(ssn.LongFormat.Substring(ssn.LongFormat.Length - 6, 2)) - 60;
             string strDay = day < 10 ? $"0{day}" : day.ToString();
 
             DateTime dt = DateTime.ParseExact(ssn.LongFormat.Substring(0, ssn.LongFormat.Length - 6) + strDay, "yyyyMMdd", CultureInfo.InvariantCulture, DateTimeStyles.None);
-            int years = timeProvider.GetLocalNow().Year - dt.Year;
+            var years = localNow.Year - dt.Year;
+            if (!(localNow.Month > dt.Month || (localNow.Month == dt.Month && localNow.Day >= dt.Day)))
+            {
+                years--;
+            }
 
             Assert.Equal(years, Personnummer.Parse(ssn.SeparatedLong, new Personnummer.Options { AllowCoordinationNumber = true, TimeProvider = timeProvider }).Age);
             Assert.Equal(years, Personnummer.Parse(ssn.SeparatedFormat, new Personnummer.Options { AllowCoordinationNumber = true, TimeProvider = timeProvider }).Age);

Personnummer.Tests/PersonnummerTests.cs

@@ -82,15 +82,35 @@ public void TestParseInvalid(PersonnummerData ssn)
         public void TestAge(PersonnummerData ssn)
         {
             var timeProvider = new TestTimeProvider();
+            var localNow = timeProvider.GetLocalNow();
             DateTime dt = DateTime.ParseExact(ssn.LongFormat.Substring(0, ssn.LongFormat.Length - 4), "yyyyMMdd", CultureInfo.InvariantCulture, DateTimeStyles.None);
-            int years = timeProvider.GetLocalNow().Year - dt.Year;
+
+            var years = localNow.Year - dt.Year;
+            if (!(localNow.Month > dt.Month || (localNow.Month == dt.Month && localNow.Day >= dt.Day)))
+            {
+                years--;
+            }
 
             Assert.Equal(years, Personnummer.Parse(ssn.SeparatedLong, new Personnummer.Options { AllowCoordinationNumber = false, TimeProvider = timeProvider }).Age);
             Assert.Equal(years, Personnummer.Parse(ssn.SeparatedFormat, new Personnummer.Options { AllowCoordinationNumber = false, TimeProvider = timeProvider }).Age);
             Assert.Equal(years, Personnummer.Parse(ssn.LongFormat, new Personnummer.Options { AllowCoordinationNumber = false, TimeProvider = timeProvider }).Age);
             // Du to age not being possible to fetch from >100 year short format without separator, we aught to check this here.
             Assert.Equal(years > 99 ? years - 100 : years, Personnummer.Parse(ssn.ShortFormat, new Personnummer.Options { AllowCoordinationNumber = false, TimeProvider = timeProvider }).Age);
         }
+
+        [Fact]
+        public void TestEdgeCasesAroundBirthday()
+        {
+            var timeProvider = new TestTimeProvider
+            {
+                Now = DateTimeOffset.Parse("2090-01-09 12:00")
+            };
+
+            Assert.Equal(10, new Personnummer("20800108-6670", new Personnummer.Options() {TimeProvider = timeProvider} ).Age); // Had birthday yesterday
+            Assert.Equal(10, new Personnummer("20800109-8287", new Personnummer.Options() {TimeProvider = timeProvider} ).Age); // Birthday today
+            Assert.Equal(9, new Personnummer("20800110-8516", new Personnummer.Options() {TimeProvider = timeProvider} ).Age); // Upcoming Birthday tomorrow
+        }
+
 #endif
 
         [Theory]

Personnummer.Tests/TestTimeProvider.cs

@@ -10,7 +10,7 @@ namespace Personnummer.Tests;
 public class TestTimeProvider : TimeProvider
 {
     internal DateTimeOffset Now { get; set; } = new(
-        new DateOnly(2025, 1, 5),
+        new DateOnly(2025, 1, 1),
         new TimeOnly(0, 0, 0, 1),
         TimeSpan.Zero
     );

Personnummer/Personnummer.cs

@@ -46,7 +46,10 @@ public int Age
                 var now = _options.DateTimeNow;
                 var age = now.Year - Date.Year;
 
-                if (now.Month >= Date.Month && now.Day >= Date.Day)
+                var hadBirthdayThisYear = now.Month > Date.Month ||
+                                        (now.Month == Date.Month && now.Day >= Date.Day);
+
+                if (!hadBirthdayThisYear)
                 {
                     age--;
                 }