v1.4.2

- Added the `isLeapYear` extension to the `DateTime` and `int` objects.
- Added the `FixedSizeList` class.

test/classes/fixed_size_list_test.dart

@@ -0,0 +1,75 @@
+import "package:arcane_helper_utils/arcane_helper_utils.dart";
+import "package:test/test.dart";
+
+void main() {
+  group("FixedSizeList", () {
+    test("initial list is empty", () {
+      final list = FixedSizeList(5);
+      expect(list.items, isEmpty);
+    });
+
+    test("adding elements below capacity", () {
+      final list = FixedSizeList(3);
+      list.add("one");
+      expect(list.items, ["one"]);
+      list.add("two");
+      expect(list.items, ["one", "two"]);
+    });
+
+    test("adding elements up to capacity", () {
+      final list = FixedSizeList(2);
+      list.add("a");
+      list.add("b");
+      expect(list.items, ["a", "b"]);
+    });
+
+    test("adding elements beyond capacity removes the oldest", () {
+      final list = FixedSizeList(2);
+      list.add("first");
+      list.add("second");
+      expect(list.items, ["first", "second"]);
+      list.add("third");
+      expect(list.items, ["second", "third"]);
+      list.add("fourth");
+      expect(list.items, ["third", "fourth"]);
+    });
+
+    test("capacity of zero results in an empty list that stays empty", () {
+      final list = FixedSizeList(0);
+      list.add("anything");
+      expect(list.items, isEmpty);
+      list.add("something else");
+      expect(list.items, isEmpty);
+    });
+
+    test("items getter returns an unmodifiable list", () {
+      final list = FixedSizeList(2);
+      list.add("alpha");
+      list.add("beta");
+      final items = list.items;
+      expect(() => items.add("gamma"), throwsUnsupportedError);
+
+      // Ensure original list is not modified
+      expect(list.items, ["alpha", "beta"]);
+    });
+
+    test("adding multiple elements beyond capacity", () {
+      final list = FixedSizeList(1);
+      list.add("one");
+      list.add("two");
+      list.add("three");
+      list.add("four");
+      expect(list.items, ["four"]);
+    });
+
+    test("adding the same element multiple times", () {
+      final list = FixedSizeList(3);
+      list.add("same");
+      list.add("same");
+      list.add("same");
+      expect(list.items, ["same", "same", "same"]);
+      list.add("different");
+      expect(list.items, ["same", "same", "different"]);
+    });
+  });
+}