feat(core): 新增 WeightedPick 加权随机共享原语(+10 单测),为消除四处平行实现做准备

2026-07-27 09:54:34 +08:00
parent c3ab961d3b
commit 3d85f65965
2 changed files with 149 additions and 0 deletions
@@ -0,0 +1,98 @@
+using System.Collections.Generic;
+using NUnit.Framework;
+using BaseGames.Core;
+
+namespace BaseGames.Tests.EditMode.Core
+{
+    /// <summary>
+    /// WeightedPick 加权随机取索引的共享原语测试。
+    /// 该原语被敌人选招 / Boss 选招 / 战利品掉落共用，故对"绝不选中零权重项"等
+    /// 确定性性质做强断言（多次采样），避免任一消费端出现选到不合格项的缺陷。
+    /// </summary>
+    public class WeightedPickTests
+    {
+        static List<float> W(params float[] w) => new List<float>(w);
+
+        [Test]
+        public void Null_ReturnsMinusOne()
+        {
+            Assert.AreEqual(-1, WeightedPick.Index(null));
+        }
+
+        [Test]
+        public void Empty_ReturnsMinusOne()
+        {
+            Assert.AreEqual(-1, WeightedPick.Index(W()));
+        }
+
+        [Test]
+        public void AllZero_ReturnsMinusOne()
+        {
+            Assert.AreEqual(-1, WeightedPick.Index(W(0f, 0f, 0f)));
+        }
+
+        [Test]
+        public void AllNegative_ReturnsMinusOne()
+        {
+            // 负权重按 0 处理（非法输入不应造成负总和/错误索引）
+            Assert.AreEqual(-1, WeightedPick.Index(W(-1f, -5f)));
+        }
+
+        [Test]
+        public void SinglePositive_AlwaysThatIndex()
+        {
+            var w = W(0f, 3f, 0f);
+            for (int i = 0; i < 50; i++)
+                Assert.AreEqual(1, WeightedPick.Index(w));
+        }
+
+        [Test]
+        public void NeverPicksZeroWeight()
+        {
+            // 索引 0/2 权重为 0，无论抽多少次都不该被选中
+            var w = W(0f, 1f, 0f, 2f);
+            for (int i = 0; i < 200; i++)
+            {
+                int idx = WeightedPick.Index(w);
+                Assert.IsTrue(idx == 1 || idx == 3, $"选中了零权重索引 {idx}");
+            }
+        }
+
+        [Test]
+        public void NeverPicksNegativeWeight()
+        {
+            var w = W(-10f, 1f);
+            for (int i = 0; i < 200; i++)
+                Assert.AreEqual(1, WeightedPick.Index(w));
+        }
+
+        [Test]
+        public void AllPositive_EveryIndexReachable()
+        {
+            // 等权重下，足够多次采样应覆盖所有索引（验证不会恒定只返回首个/末个）
+            var w = W(1f, 1f, 1f);
+            var seen = new HashSet<int>();
+            for (int i = 0; i < 500; i++) seen.Add(WeightedPick.Index(w));
+            CollectionAssert.AreEquivalent(new[] { 0, 1, 2 }, seen);
+        }
+
+        [Test]
+        public void HeavyWeight_DominatesDistribution()
+        {
+            // 权重 99:1 时，重权重索引应占绝大多数（宽松阈值，避免随机性造成偶发失败）
+            var w = W(99f, 1f);
+            int heavy = 0;
+            const int N = 1000;
+            for (int i = 0; i < N; i++) if (WeightedPick.Index(w) == 0) heavy++;
+            Assert.Greater(heavy, N * 0.9f, $"重权重仅被选中 {heavy}/{N} 次，分布不符合权重");
+        }
+
+        [Test]
+        public void WorksWithArray()
+        {
+            // IReadOnlyList 契约：数组同样可用（消费端可复用缓存数组，免 GC）
+            float[] w = { 0f, 5f };
+            Assert.AreEqual(1, WeightedPick.Index(w));
+        }
+    }
+}