fix: Calculation of persons age

wrestling_scoreboard_common/lib/src/data/person.dart

@@ -72,7 +72,7 @@ class Person with _$Person implements DataObject, Organizational {
       final monthDiff = today.month - birthDate!.month;
       final dayDiff = today.day - birthDate!.day;
 
-      return monthDiff >= 0 && dayDiff >= 0 ? yearDiff : yearDiff - 1;
+      return monthDiff > 0 || (monthDiff == 0 && dayDiff >= 0) ? yearDiff : yearDiff - 1;
     }
     return null;
   }

wrestling_scoreboard_common/test/data/person_test.dart

@@ -0,0 +1,43 @@
+import 'package:test/test.dart';
+import 'package:wrestling_scoreboard_common/common.dart';
+
+void main() {
+  test('Persons age', () {
+    MockableDateTime.isMocked = true;
+
+    final personA = Person(prename: 'John', surname: 'Doe', birthDate: DateTime(2015, 8, 1));
+    final personB = Person(prename: 'Max', surname: 'Muster', birthDate: DateTime(2015, 7, 31));
+    final personC = Person(prename: 'Ashok', surname: 'Kumar', birthDate: DateTime(2015, 1, 1));
+    final personD = Person(prename: 'Fred', surname: 'Nurk', birthDate: DateTime(2014, 12, 31));
+
+    MockableDateTime.mockedDateTime = DateTime(2020, 12, 30);
+    expect(personA.age, 5);
+    expect(personB.age, 5);
+    expect(personC.age, 5);
+    expect(personD.age, 5);
+
+    MockableDateTime.mockedDateTime = DateTime(2020, 12, 31);
+    expect(personA.age, 5);
+    expect(personB.age, 5);
+    expect(personC.age, 5);
+    expect(personD.age, 6);
+
+    MockableDateTime.mockedDateTime = DateTime(2021, 1, 1);
+    expect(personA.age, 5);
+    expect(personB.age, 5);
+    expect(personC.age, 6);
+    expect(personD.age, 6);
+
+    MockableDateTime.mockedDateTime = DateTime(2021, 7, 31);
+    expect(personA.age, 5);
+    expect(personB.age, 6);
+    expect(personC.age, 6);
+    expect(personD.age, 6);
+
+    MockableDateTime.mockedDateTime = DateTime(2021, 8, 1);
+    expect(personA.age, 6);
+    expect(personB.age, 6);
+    expect(personC.age, 6);
+    expect(personD.age, 6);
+  });
+}