9f4769a4c9
- 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
125 lines
4.3 KiB
TypeScript
125 lines
4.3 KiB
TypeScript
import { describe, expect, it } from 'vitest'
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import { getRandomElements } from '@/views/Home/utils/random'
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describe('getRandomElements', () => {
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// 测试基本功能：从数组中获取指定数量的元素
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it('should return specified number of elements', () => {
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const sourceArray = [1, 2, 3, 4, 5]
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const result = getRandomElements(sourceArray, 3)
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expect(result).toHaveLength(3)
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result.forEach((element) => {
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expect(sourceArray).toContain(element)
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})
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})
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// 测试边界情况：count为0
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it('should return empty array when count is 0', () => {
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const sourceArray = [1, 2, 3]
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const result = getRandomElements(sourceArray, 0)
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expect(result).toEqual([])
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})
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// 测试边界情况：count为负数
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it('should return empty array when count is negative', () => {
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const sourceArray = [1, 2, 3]
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const result = getRandomElements(sourceArray, -1)
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expect(result).toEqual([])
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})
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// 测试边界情况：count大于等于数组长度
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it('should return shuffled array when count equals or exceeds array length', () => {
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const sourceArray = [1, 2, 3]
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const result1 = getRandomElements(sourceArray, 3)
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const result2 = getRandomElements(sourceArray, 5)
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expect(result1).toHaveLength(3)
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expect(result2).toHaveLength(3)
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// 验证返回的元素与原数组相同
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expect(result1.sort()).toEqual(sourceArray.sort())
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expect(result2.sort()).toEqual(sourceArray.sort())
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})
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// 测试空数组情况
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it('should return empty array when source array is empty', () => {
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const sourceArray: number[] = []
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const result = getRandomElements(sourceArray, 3)
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expect(result).toEqual([])
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})
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// 测试单元素数组
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it('should handle single element array', () => {
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const sourceArray = [42]
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const result = getRandomElements(sourceArray, 1)
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expect(result).toEqual([42])
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})
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// 测试字符串数组
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it('should work with string arrays', () => {
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const sourceArray = ['a', 'b', 'c', 'd', 'e']
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const result = getRandomElements(sourceArray, 2)
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expect(result).toHaveLength(2)
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result.forEach((element) => {
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expect(sourceArray).toContain(element)
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})
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})
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// 测试对象数组
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it('should work with object arrays', () => {
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const sourceArray = [
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{ id: 1, name: 'Alice' },
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{ id: 2, name: 'Bob' },
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{ id: 3, name: 'Charlie' },
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]
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const result = getRandomElements(sourceArray, 2)
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expect(result).toHaveLength(2)
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result.forEach((element) => {
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expect(sourceArray).toContain(element)
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})
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})
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// 测试多次调用应产生不同结果（概率性测试）
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it('should produce different results on multiple calls', () => {
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const sourceArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
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const results = new Set()
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// 多次调用并收集结果
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for (let i = 0; i < 10; i++) {
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const result = getRandomElements(sourceArray, 5).sort().join(',')
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results.add(result)
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}
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// 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
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expect(results.size).toBeGreaterThan(1)
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})
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// 多次调用，每个元素抽中的概率基本上相等
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it('should have approximately equal probabilities for each element', () => {
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const sourceArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
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const times = 200000 // 次数
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const count = 5 // 抽奖个数
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const expectedProbability = count / sourceArray.length
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const elementCounts = new Map()
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// 多次调用并统计元素出现的次数
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for (let i = 0; i < times; i++) {
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const result = getRandomElements(sourceArray, count)
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result.forEach((element) => {
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const count = elementCounts.get(element) || 0
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elementCounts.set(element, count + 1)
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})
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}
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elementCounts.forEach((value) => {
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// 验证每个元素出现的概率接近相等
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const probability = value / times
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expect(probability).toBeCloseTo(expectedProbability, 2)
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})
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})
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})
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