JavaScript测试框架中动态生成测试用例的策略与时序管理

let a = []; // 初始时，a 是一个空数组

describe('Testing Dynamic Cases', () => {
    before(() => {
        // 这个钩子在 describe 块解析完毕，但测试用例开始执行前运行
        a = [1, 2, 3, 4, 5]; // 此时 a 被赋值
        console.log('Inside before hook, a:', a); // 输出：[1, 2, 3, 4, 5]
    });

    it('should test the first element of a', (done) => {
        expect(a[0]).to.equal(1);
        done();
    });

    // 这个 forEach 循环在 describe 块解析时立即执行
    // 此时 before 钩子还未运行！
    console.log('During describe parsing, a:', a); // 输出：[]
    a.forEach(value => {
        it(`should return ${value}+1`, () => {
          expect(value + 1).to.be.eql(value + 1);
        });
      });
});

// 策略一：数据在 describe 块解析时同步可用
const testData = [1, 2, 3, 4, 5]; // 数据在 describe 块解析前就已定义

describe('Testing Dynamic Cases with Synchronous Data', () => {
    before(() => {
        // before 钩子可以用于其他设置，但不再负责 testData 的初始化
        console.log('Setup before all tests.');
    });

    it('should test the first element of testData', () => {
        expect(testData[0]).to.equal(1);
    });

    // forEach 循环在 describe 块解析时执行，testData 已有值
    testData.forEach(value => {
        it(`should verify value ${value}`, () => {
          expect(value).to.be.eql(value); // 示例断言
        });
    });

    // 也可以将数据定义在 describe 块内部，只要在 forEach 前定义即可
    const moreData = ['a', 'b'];
    moreData.forEach(char => {
        it(`should process character ${char}`, () => {
            expect(typeof char).to.equal('string');
        });
    });
});

// 策略二：使用 Jest 的 test.each 进行参数化测试
const testCases = [
    { input: 1, expected: 2 },
    { input: 2, expected: 3 },
    { input: 3, expected: 4 },
];

describe('Testing Dynamic Cases with Jest.each', () => {
    // test.each 可以直接接收数组或模板字符串
    test.each(testCases)('should return %s + 1 = %s', ({ input, expected }) => {
        expect(input + 1).toBe(expected);
    });

    // 也可以使用 describe.each 来创建多个 describe 块
    describe.each([
        { type: 'positive', data: [1, 2] },
        { type: 'negative', data: [-1, -2] },
    ])('Test suite for %s numbers', ({ type, data }) => {
        test.each(data)('should correctly handle %s %s number', (num) => {
            if (type === 'positive') {
                expect(num).toBeGreaterThan(0);
            } else {
                expect(num).toBeLessThan(0);
            }
        });
    });
});

let dynamicData = []; // 声明变量

describe('Testing with data from before hook', () => {
    before(async () => {
        // 模拟异步数据加载
        dynamicData = await new Promise(resolve => setTimeout(() => resolve([10, 20, 30]), 100));
        console.log('Data loaded in before hook:', dynamicData);
    });