test: add tests for the isBetween function

test/extensions_test.dart

@@ -0,0 +1,46 @@
+import 'package:flutter_card_swiper/src/extensions.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('isBetween', () {
+    test('should return true when value is within range', () {
+      const value = 5;
+      const from = 1;
+      const to = 10;
+
+      final result = value.isBetween(from, to);
+
+      expect(result, isTrue);
+    });
+
+    test('should return true when value is equal to the range limits', () {
+      const value = 1;
+      const from = 1;
+      const to = 1;
+
+      final result = value.isBetween(from, to);
+
+      expect(result, isTrue);
+    });
+
+    test('should return false when value is outside the range', () {
+      const value = 15;
+      const from = 1;
+      const to = 10;
+
+      final result = value.isBetween(from, to);
+
+      expect(result, isFalse);
+    });
+
+    test('should return false when the range limits are inverted', () {
+      const value = 5;
+      const from = 10;
+      const to = 1;
+
+      final result = value.isBetween(from, to);
+
+      expect(result, isFalse);
+    });
+  });
+}