如何在 deno 中模拟我的 mongodb 数据库/客户端？

Question

I was trying to write some unit tests and mock some functions that make network calls and more. I see that Deno's testing module only provides asserts to work with. Is there a good library or something I can use for Deno to make mocks for tests?

Best regards Thnaks you for your help!

Answer 1

There's no mocking functionality in the Deno Standard Library ( std ) but you can find a few libraries/modules/frameworks that provide mocking on deno.land/x . Rhum , for example, provides mocks. Here's an example from their docs:

class ToBeMocked { ... }

const mock = Rhum
  .mock(ToBeMocked)
  .withConstructorArgs("someArg") // if the class to be mocked has a constructor and it requires args
  .create();

Keep in mind that most Deno modules are still being actively developed so they may not have every piece of functionality just yet. I don't know if any of Node's testing frameworks work on Deno, but if so you could use one of those (Jest/Jasmine/Mocha etc.)

Answer 2

I have not personally used Deno's testing suite but mocking follows the same patterns throughout most testing frameworks. Generally you would define a mock object or function and you explicitly define the behavior to your liking.

In terms of database calls, you would most likely mock the module or implementation making the call and return your expect mocked result.

Jest is a great testing framework that provides this ability.

Here is an example of mocking an Axios call ( https://jestjs.io/docs/mock-functions ). You can replace the axios example for your mongodb scenario.

// users.js
import axios from 'axios';

class Users {
  static all() {
    return axios.get('/users.json').then(resp => resp.data);
  }
}

export default Users;

// users.test.js
import axios from 'axios';
import Users from './users';

jest.mock('axios');

test('should fetch users', () => {
  const users = [{name: 'Bob'}];
  const resp = {data: users};
  axios.get.mockResolvedValue(resp);

  // or you could use the following depending on your use case:
  // axios.get.mockImplementation(() => Promise.resolve(resp))

  return Users.all().then(data => expect(data).toEqual(users));
});