Merge pull request #15 from passsy/feature/comparison_tests

Add comparisons tests

lib/src/comparisons.dart

@@ -20,30 +20,18 @@ Comparator<T> reverse<T>(Comparator<T> comparator) {
   return compareTo;
 }
 
-//class _ReversedComparator<T> {
-//  _ReversedComparator(this.comparator);
-//
-//  Comparator<T> comparator;
-//
-//  int compareTo(T a, T b) => comparator(b, a);
-//}
-
+/**
+ * Creates a comparator using the function to transform value to a [Comparable] instance for comparison.
+ */
 Comparator<T> compareBy<T>(Comparable Function(T) selector) {
   int compareTo(T a, T b) => selector(a).compareTo(selector(b));
-
   return compareTo;
 }
 
+/**
+ * Creates a descending comparator using the function to transform value to a [Comparable] instance for comparison.
+ */
 Comparator<T> compareByDescending<T>(Comparable Function(T) selector) {
   int compareTo(T a, T b) => selector(b).compareTo(selector(a));
-
   return compareTo;
 }
-
-//class _CompareBy<T> {
-//  Comparable Function(T) selector;
-//
-//  _CompareBy(this.selector);
-//
-//  int compareTo(T a, T b) => selector(a).compareTo(selector(b));
-//}

test/comparisons_test.dart

@@ -0,0 +1,28 @@
+import 'package:dart_kollection/dart_kollection.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('compare in natural order', () {
+    test("naturalOrder", () {
+      final list = listOf([3, 4, 5, 2, 1]);
+      final natural = list.sortedWith(naturalOrder());
+      expect(natural, listOf([1, 2, 3, 4, 5]));
+    });
+  });
+
+  group('compare reversed order', () {
+    test("reverseOrder", () {
+      final list = listOf([3, 4, 5, 2, 1]);
+      final natural = list.sortedWith(reverseOrder());
+      expect(natural, listOf([5, 4, 3, 2, 1]));
+    });
+  });
+
+  group("reverse custom comparator", () {
+    test("reverse natural", () {
+      final list = listOf([3, 4, 5, 2, 1]);
+      final reversedNatural = list.sortedWith(reverse(naturalOrder()));
+      expect(reversedNatural, listOf([5, 4, 3, 2, 1]));
+    });
+  });
+}

test/dart_kollection_test.dart

@@ -9,11 +9,13 @@ import 'collection/map_mutable_extensions_test.dart' as map_mutable_extensions_t
 import 'collection/map_test.dart' as map_test;
 import 'collection/set_test.dart' as set_test;
 import 'collections_test.dart' as collections_test;
+import 'comparisons_test.dart' as comparisons_test;
 import 'exceptions_test.dart' as exceptions_test;
 import 'tuples_test.dart' as tuples_test;
 
 main() {
   collections_test.main();
+  comparisons_test.main();
   exceptions_test.main();
   tuples_test.main();
   iterable_extensions_test.main();