add comments and a unit test for the date parsing to ensure it lines up with third-party real life examples and my blog post

Author: MoralCode

lib/extensions.dart

@@ -6,9 +6,9 @@ extension Concept2DateExtension on DateTime {
     int date =
         CsafeIntExtension.fromBytes(bytes.sublist(0, 2), endian: Endian.little);
 
-    int month = date & 0x0F;
-    int day = (date >> 4) & 0x1F;
-    int year = (date >> 9) & 0x7f;
+    int month = date & 0x0F; //lowest 4 bits of Date LO
+    int day = (date >> 4) & 0x1F; // Next 5 bits
+    int year = (date >> 9) & 0x7f; // Next 7 bits
 
     int minutes =
         CsafeIntExtension.fromBytes(bytes.sublist(2, 3), endian: Endian.little);

test/extensions_test.dart

@@ -19,6 +19,18 @@ void main() {
       // expect(CsafeIntExtension.fromBytes(bytes, Endian.little), 2147483648);
     });
 
+    test('converting a date from a verifiable source from bytes', () {
+      // https://www.c2forum.com/viewtopic.php?t=93684
+      //  DateH     DateL     TimeH    TimeL
+      // 00011101 10010100  00010000 00001001
+      // final bytes = Uint8List.fromList([29, 148, 16, 9]);
+      final bytes = Uint8List.fromList([148, 29, 9, 16]);
+
+      expect(Concept2DateExtension.fromBytes(bytes),
+          DateTime(2014, 4, 25, 16, 09));
+      // 25th April 2014 @ 16:09 (4:09pm)
+    });
+
     test('converting a date in 2022 from bytes', () {
       final bytes = Uint8List.fromList([133, 44, 14, 14]);
       expect(