test(random): 添加随机元素抽取函数的全面测试用例 Test #91

- 新增 Random.test.ts 文件，对 getRandomElements 函数进行详尽测试
- 包括基础功能、边界情况（count 为 0、负数、超出数组长度）
- 支持空数组、单元素数组、字符串数组、对象数组等多种数据类型
- 增加概率性测试，验证多次调用结果不完全一致
- 20万次循环验证各元素被抽中概率接近理论值，确保算法公平性

__test__/Random.test.ts

@@ -0,0 +1,124 @@
+import { describe, expect, it } from 'vitest'
+import { getRandomElements } from '@/views/Home/utils/random'
+
+describe('getRandomElements', () => {
+    // 测试基本功能：从数组中获取指定数量的元素
+    it('should return specified number of elements', () => {
+        const sourceArray = [1, 2, 3, 4, 5]
+        const result = getRandomElements(sourceArray, 3)
+
+        expect(result).toHaveLength(3)
+        result.forEach((element) => {
+            expect(sourceArray).toContain(element)
+        })
+    })
+
+    // 测试边界情况：count为0
+    it('should return empty array when count is 0', () => {
+        const sourceArray = [1, 2, 3]
+        const result = getRandomElements(sourceArray, 0)
+
+        expect(result).toEqual([])
+    })
+
+    // 测试边界情况：count为负数
+    it('should return empty array when count is negative', () => {
+        const sourceArray = [1, 2, 3]
+        const result = getRandomElements(sourceArray, -1)
+
+        expect(result).toEqual([])
+    })
+
+    // 测试边界情况：count大于等于数组长度
+    it('should return shuffled array when count equals or exceeds array length', () => {
+        const sourceArray = [1, 2, 3]
+        const result1 = getRandomElements(sourceArray, 3)
+        const result2 = getRandomElements(sourceArray, 5)
+
+        expect(result1).toHaveLength(3)
+        expect(result2).toHaveLength(3)
+
+        // 验证返回的元素与原数组相同
+        expect(result1.sort()).toEqual(sourceArray.sort())
+        expect(result2.sort()).toEqual(sourceArray.sort())
+    })
+
+    // 测试空数组情况
+    it('should return empty array when source array is empty', () => {
+        const sourceArray: number[] = []
+        const result = getRandomElements(sourceArray, 3)
+
+        expect(result).toEqual([])
+    })
+
+    // 测试单元素数组
+    it('should handle single element array', () => {
+        const sourceArray = [42]
+        const result = getRandomElements(sourceArray, 1)
+
+        expect(result).toEqual([42])
+    })
+
+    // 测试字符串数组
+    it('should work with string arrays', () => {
+        const sourceArray = ['a', 'b', 'c', 'd', 'e']
+        const result = getRandomElements(sourceArray, 2)
+
+        expect(result).toHaveLength(2)
+        result.forEach((element) => {
+            expect(sourceArray).toContain(element)
+        })
+    })
+
+    // 测试对象数组
+    it('should work with object arrays', () => {
+        const sourceArray = [
+            { id: 1, name: 'Alice' },
+            { id: 2, name: 'Bob' },
+            { id: 3, name: 'Charlie' },
+        ]
+        const result = getRandomElements(sourceArray, 2)
+
+        expect(result).toHaveLength(2)
+        result.forEach((element) => {
+            expect(sourceArray).toContain(element)
+        })
+    })
+
+    // 测试多次调用应产生不同结果（概率性测试）
+    it('should produce different results on multiple calls', () => {
+        const sourceArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
+        const results = new Set()
+
+        // 多次调用并收集结果
+        for (let i = 0; i < 10; i++) {
+            const result = getRandomElements(sourceArray, 5).sort().join(',')
+            results.add(result)
+        }
+
+        // 虽然有极小概率会相同，但大多数情况下应该有不同的结果
+        expect(results.size).toBeGreaterThan(1)
+    })
+    // 多次调用，每个元素抽中的概率基本上相等
+    it('should have approximately equal probabilities for each element', () => {
+        const sourceArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
+        const times = 200000 // 次数
+        const count = 5 // 抽奖个数
+        const expectedProbability = count / sourceArray.length
+        const elementCounts = new Map()
+
+        // 多次调用并统计元素出现的次数
+        for (let i = 0; i < times; i++) {
+            const result = getRandomElements(sourceArray, count)
+            result.forEach((element) => {
+                const count = elementCounts.get(element) || 0
+                elementCounts.set(element, count + 1)
+            })
+        }
+        elementCounts.forEach((value) => {
+            // 验证每个元素出现的概率接近相等
+            const probability = value / times
+            expect(probability).toBeCloseTo(expectedProbability, 2)
+        })
+    })
+})