Question

我熟悉RSpec，通过编写共享示例可以很容易地重用测试用例

shared_example_for 'a cute pet' do 
  it 'tests that the pet is a small' { expect(pet.size).to be_lesser_than(10) }
  it 'tests that the pet can smile' { expect(pet.can_smile?).to be }
end

describe 'The Octocat' do
  let(:pet) Octocat.new

  it_behaves_like 'a cute pet'
end
...
describe 'The Doge' do 
  let(:pet) Doge.new

  it_behaves_like 'a cute pet'
end

在玩笑中有同等的吗？是什么让我可以重用beforeEach（）块中设置的变量？我正在尝试使用以下方法找到一种方法：

const cutenessTests = function() {
  test('it is small', () => {
    expect(petSetInBefore.length).toBeLesserThan(5)
  })
  test('it can smile', () => {
    expect(petSetInBefore.canSmile).toBe(true)
  })
}

describe('Famous animals', () => {
  let petSetInBefore;

  describe('Octocat', () => {
    beforeEach(() => {
      petSetInBefore = new Octocat();
    })

    cutenessTests.bind(this)()
  })
})

这里重要的是，我要共享多个test定义，而不仅仅是一个，否则我可以将petSetInBefore传递给共享函数

Answer 1

您可以简单地将共享测试移动到执行it()调用的函数中。

class Octocat {
  get length() {
    return 3;
  }

  get canSmile() {
    return true;
  }
}

class GrumpyCat {
  get length() {
    return 1;
  }

  get canSmile() {
    return false;
  }
}

const behavesLikeAPet = (pet) => {
  it('is small', () => expect(pet.length).toBeLessThan(5));
  it('can smile', () => expect(pet.canSmile).toEqual(true));
};

describe('Famous animals', () => {
  describe('Octocat', () => {
    behavesLikeAPet(new Octocat());
  });

  describe('GrumpyCat', () => {
    behavesLikeAPet(new GrumpyCat());
  });
});

您将获得每个it测试的详细输出：

Famous animals
  Octocat
    ✓ is small (2ms)
    ✓ can smile (1ms)
  GrumpyCat
    ✓ is small
    ✕ can smile (2ms)

Answer 2

如果您仍然希望 beforeEach ，

由于某些原因...如果您在全局范围内声明变量，它会起作用

let petSetInBefore; // here it works
describe('Famous animals', () => {
  //let petSetInBefore; // here it's undefined

  describe('Octocat', ()  => {
    //let petSetInBefore; // undefined too

    beforeAll(() => {
      petSetInBefore = new Octocat();
    })

    cutenessTests() // .bind(this) results the same
  });

  describe('Doge', () => {
    beforeEach(() => {
      petSetInBefore = new Doge();
    })

    cutenessTests.bind(this)()
  });
})

https://repl.it/@gui3/jestSharedTests

似乎共享函数中的测试无法共享 beforeEach 中的变量，否则...

Answer 3

Jest拥有describe.each(table)，我还没看到它经常使用，但是对于重用具有相同/相同结果的测试确实很有帮助。

如果对两个测试主题的期望都相同，您可以这样做：

const aCutePet = pet => {
  it("should be small", () => {
    expect(pet.size).toBeLessThan(10);
  });

  it(`should be able to smile`, () => {
    expect(pet).toHaveProperty('can_smile', true)
  });
}

describe.each([
  [new Doge],
  [new Octocat]
])("The %O", aCutePet);

输出：

  The Doge { size: 3, can_smile: true }
    ✓ should be small (1ms)
    ✓ should be able to smile (1ms)
  The Octocat { size: 5, can_smile: true }
    ✓ should be small
    ✓ should be able to smile (1ms)

开玩笑-在一个describe块中导入多个测试，重用beforeEach（）中定义的变量

3 个答案: