unit-testing - 在 Jest 中，当使用函数生成 describe/it block 时，有没有办法让 beforeAll/beforeEach block 在断言之前运行？

Question

当使用函数生成测试文件中经常使用的describe/it block 时，beforeAll 或beforeEach 存在于父 describe 中的 block 将被忽略。

例如:

const repeatedTests = (num) => {
  // DOES NOT WORK - num is undefined
  describe(`Testing number ${num}`, () => {
    it('should exist', () => {
      expect(num).toBeDefined();
    });
    it('should be a number', () => {
      expect(num).not.toBeNaN();
    });
    it('should be less than 5', () => {
      expect(num).toBeLessThan(5);
    });
  });
};

describe.each([[1],[2],[3]])('Describe for %i', (num) => {
  let numForTesting;
  beforeAll(() => {
    numForTesting = num;
  });
  repeatedTests(numForTesting);
});

我理解为什么会这样 - repeatedTests 将立即运行，因为测试运行器不是 describe/it当心。

为了让它工作，我需要做这样的事情:

const repeatedTests = (num) => {
  describe(`Testing number ${num}`, () => {
    let numForTesting;
    beforeAll(() => {
      numForTesting = num;
    });
    it('should exist', () => {
      expect(numForTesting).toBeDefined();
    });
    it('should be a number', () => {
      expect(numForTesting).not.toBeNaN();
    });
    it('should be less than 5', () => {
      expect(numForTesting).toBeLessThan(5);
    });
  });
};

describe.each([[1],[2],[3]])('Describe for %i', (num) => {
  repeatedTests(num);
});

在我正在处理的特定测试套件中(它比这复杂得多，如果不是很明显的话)- 以这种方式做事会使事情变得非常棘手，并且使生成器函数的重用变得非常具有挑战性。

有没有办法让 beforeAll 或 beforeEach 在函数内部生成的测试 block 之前运行，就像我原来的例子一样？

就其值(value)而言，在我上面的简单示例中设置 num 相当于使用 enzymemount react 节点。

Answer 1

Is there any way to have a beforeAll or beforeEach run before a testing block that's generated inside of a function, a la my original example?

鉴于您提到的原因，我的感觉是答案是否定的。

这是一种可能满足您需要的不同方法。它使用 generateState 函数而不是 jest hook。

const repeatedTests = (generateState) => {

    const num = generateState();

    describe(`Testing number ${num}`, () => {
        it('should exist', () => {
            expect(num).toBeDefined();
        });
        it('should be a number', () => {
            expect(num).not.toBeNaN();
        });
        it('should be less than 5', () => {
            expect(num).toBeLessThan(5);
        });
    });
};

describe.each([[1], [2], [3]])('Describe for %i', (num) => {

    const generateState = () => {
        return num;
    }

    repeatedTests(generateState);
});

这是测试输出:

 PASS  ./index.test.js
  Describe for 1
    Testing number 1
      √ should exist (4ms)
      √ should be a number (1ms)
      √ should be less than 5
  Describe for 2
    Testing number 2
      √ should exist
      √ should be a number
      √ should be less than 5 (1ms)
  Describe for 3
    Testing number 3
      √ should exist
      √ should be a number (1ms)
      √ should be less than 5