--update: fix and test for empty collection for randomOrNull

passsy · Oct 25, 2021 · eda96a6 · eda96a6
1 parent 9390e38
commit eda96a6
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diff --git a/lib/src/collection/kt_collection.dart b/lib/src/collection/kt_collection.dart
@@ -40,6 +40,7 @@ extension KtCollectionExtensions<T> on KtCollection<T> {
   ///
   /// returns null if this collection is empty.
   T? randomOrNull([math.Random? random]) {
+    if (!isNotEmpty()) return null;
     final r = random ?? math.Random();
     final index = r.nextInt(size);
     if (index >= size) return null;

diff --git a/test/collection/collection_test.dart b/test/collection/collection_test.dart
@@ -158,12 +158,19 @@ void testCollection(KtCollection<T> Function<T>() emptyCollection,
 
       final outOfRangePick = collection.randomOrNull(NotRandom()..next = 3);
       expect(outOfRangePick, null);
+
+      final emptyCollection = collectionOf([]);
+      final pick1 = emptyCollection.randomOrNull(NotRandom()..next = 0);
+      expect(pick1, null);
     });
 
     test("randomOrNull works without passing a Random", () {
       final collection = collectionOf(["a", "b", "c"]);
       expect(collection.randomOrNull(),
           anyOf(equals("a"), equals("b"), equals("c"), equals(null)));
+
+      final emptyCollection = collectionOf([]);
+      expect(emptyCollection.randomOrNull(), equals(null));
     });
   });
   group("toString", () {