Merge pull request #7 from AnnulusGames/fix-weightedlist-removerandom

Fix: RemoveRandom returns default(T) when the last element is selected
AnnulusGames · Aug 20, 2024 · af00c29 · af00c29
2 parents c248662 + 1340a52
commit af00c29
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diff --git a/src/RandomExtensions/Collections/WeightedList.cs b/src/RandomExtensions/Collections/WeightedList.cs
@@ -209,7 +209,7 @@ public void RemoveRandom(out T item)
 
     public void RemoveRandom(IRandom random, out T item)
     {
-        if (Count == 0) throw new InvalidOperationException("Empty list");
+        if (list.Count == 0) throw new InvalidOperationException("Empty list");
 
         var r = random.NextDouble() * totalWeight;
         var current = 0.0;
@@ -228,7 +228,7 @@ public void RemoveRandom(IRandom random, out T item)
             }
         }
 
-        item = default!;
+        item = list[^1].Value;
     }
 
     IEnumerator IEnumerable.GetEnumerator()

diff --git a/tests/RandomExtensions.Tests/WeightedListTests.cs b/tests/RandomExtensions.Tests/WeightedListTests.cs
@@ -14,14 +14,17 @@ public void Test_RemoveRandom()
             { 3, 3.0 },
         };
 
-        list.RemoveRandom(out _);
+        list.RemoveRandom(out var item0);
         Assert.That(list, Has.Count.EqualTo(2));
+        Assert.That(item0, Is.EqualTo(1).Or.EqualTo(2).Or.EqualTo(3));
 
-        list.RemoveRandom(out _);
+        list.RemoveRandom(out var item1);
         Assert.That(list, Has.Count.EqualTo(1));
+        Assert.That(item1, Is.EqualTo(1).Or.EqualTo(2).Or.EqualTo(3));
 
-        list.RemoveRandom(out _);
+        list.RemoveRandom(out var item2);
         Assert.That(list, Has.Count.EqualTo(0));
+        Assert.That(item2, Is.EqualTo(1).Or.EqualTo(2).Or.EqualTo(3));
 
         Assert.Throws<InvalidOperationException>(() => list.RemoveRandom(out _));
     }