Question

我正在尝试对 lambda 函数进行单元测试，但不知道如何模拟 lambda 上下文，以便在抛出错误时停止代码执行，jest 继续其单元测试。我已经尝试了一些事情，但代码继续执行或 Jest 抛出此错误：

FAIL  api/lambda.unit-test.js
  ● lambda tests › Error

    This is some mocked error

      48 |     // mock context implementation
      49 |     context.done.mockImplementation((error) => {
    > 50 |       throw new Error(error);
         |             ^
      51 |     });
      52 |     
      53 |     // function we want to test w/ mock data

      at Object.<anonymous> (api/lambda.unit-test.js:50:13)
      at foo (api/lambda.js:11:13)
      at Object.<anonymous> (api/lambda.unit-test.js:54:29)

我目前拥有的代码如下，导致上述错误...

lambda

// dependencies
const { approle } = require('./libs/approle');

// lambda function
const foo = async (event, context) => {
  const role = await approle();

  // error retrieving approle?
  if (role.error) {
    // stop lambda execution and return our error
    context.done(role.error);
  }

  return role.data;
};


// export our handler api modules
exports.foo = foo;

单元测试

// get the module we want to test
const { foo } = require('./lambda');

// mock modules
jest.mock('./libs/approle');

// import modules
const { approle } = require('./libs/approle');

// placeholder for mocking lambda context
let context;

beforeEach(() => {
  // reset mocks
  jest.resetAllMocks();

  // mock lambda context
  context = {
    done: jest.fn(),
  };
});


describe('lambda tests', () => {
  test('Success', async () => {
    // mock call to return error
    approle.mockReturnValue({
      data: 'some data'
    });
    
    // function we want to test w/ mock data
    const moduleUnderTest = await foo({}, context);

    // what we expect our moduleUnderTest to return
    const expectedResponse = 'some data';

    // test results
    expect(moduleUnderTest).toEqual(expectedResponse);
    expect(approle).toHaveBeenCalledTimes(1);
  });

  test('Error', async () => {
    // mock call to return error
    approle.mockReturnValue({
      error: 'This is some mocked error'
    });

    // mock context implementation
    context.done.mockImplementation((error) => {
      throw new Error(error);
    });
    
    // function we want to test w/ mock data
    const moduleUnderTest = await foo({}, context);

    // what we expect our moduleUnderTest to return
    const expectedResponse = 'This is some mocked error';

    // test results
    expect(moduleUnderTest).toEqual(expectedResponse);
    expect(approle).toHaveBeenCalledTimes(1);
    expect(() => { context.done(); }).toThrow(1);
  });
});

使用 Jest 对 Lamba 进行单元测试

0 个答案: