CODEWITHSUNDEEP
node.jsamazon-web-servicesunit-testingjestjsaws-sdk
Oscar Reyes
Oscar Reyes

Reputation: 4342

Node: Unable to mock aws-sdk methods

I've tried many methods i've found on the internet about mocking aws-sdk services but none of them worked for me, i've even tried the module aws-sdk-mock but that doesn't work and i think that's because i am not making use of the aws-sdk in a function handler.

I am using jest as my test runner and assertion, so the code i have now is like this:

test.js

const aws = require('aws-sdk-mock');
const Admin = require('./../../../serverless/entities/Admin');

describe('Entity - Admin test', () => {
  jest.spyOn(aws.CognitoIdentityServiceProvider.prototype, 'listUsersInGroup', () => {
    return {
      promise: Promise.resolve({ foo: 'bar' })
    };
  });

  const data = Admin.getListOfUsers();

  console.log(data);
});

Admin.js

/**
 * Admin entity class
 * This class should help managing all super user actions that are required for the sportstracker's application
 * Amazon services used by this entity:
 *  - Cognito (User Pool)
 * Required IAM Policy actions:
 *  - cognito-idp:ListUsersInGroup
 *  - cognito-idp:ListUsers
 *  - cognito-idp:AdminCreateUser
 *  - cognito-idp:AdminDeleteUser
 *  - cognito-idp:AdminGetUser
 *  - cognito-idp:AdminListGroupsForUser
 *  - cognito-idp:AdminUpdateUserAttributes
 *  - cognito-idp:AdminRemoveUserFromGroup
 */

const aws = require('aws-sdk');
const User = require('./../lib/User');
const cognito = new aws.CognitoIdentityServiceProvider();
const UserPoolId = process.env['COGNITO_USER_POOL_ID'];

const rolesMap = {
  admin: 'SuperUser',
  member: 'Member'
};

/**
 * @typedef UsersList
 * @property {Array<UserObject>} members - The list of members
 * @property {Array<UserObject>} admins - The list of admins
 */

class Admin {
  /**
   * Gets a list of users for both admin and members.
   * This executes 2 methods for aws.cognito [admin, member]
   * @returns {Promise<UsersList>} - The object containing the list of members and admins
   */
  static async getListOfUsers () {
    const operations = [
      cognito.listUsersInGroup({ UserPoolId, GroupName: rolesMap.admin }).promise(),
      cognito.listUsersInGroup({ UserPoolId, GroupName: rolesMap.member }).promise()
    ];

    const results = await Promise.all(operations);

    return {
      admins: results[0].Users.map(user => User.mapUserData(user)),
      members: results[1].Users.map(user => User.mapUserData(user))
    };
  }

  ...
}

module.exports = Admin;

the error i get for this code is:

TypeError: Cannot read property 'prototype' of undefined

this is because the prototype of all services in the sdk have no defined methods until the constructor is called, and i see why they created a module like aws-sdk-mock but even that module did not help me, so how can i make a proper way to mock the aws services in a non-function lambda handler?

Upvotes: 3

Views: 2812

Answers (2)

user14795319
user14795319

Reputation: 11

This one works for me

const AWS = require('aws-sdk');
jest.mock('aws-sdk');
    
AWS.CognitoIdentityServiceProvider.prototype.listUsers = jest.fn().mockReturnValue({
      promise: jest.fn().mockResolvedValue({})
    });

Upvotes: 1

Noel Llevares
Noel Llevares

Reputation: 16037

To mock a third-party package in jest, you can create a __mocks__ directory in the same level as your node_modules that will contain your mocked functions.

For example,

.
├── README.md
├── __mocks__
    └── aws-sdk.js
├── jest.config.js
├── node_modules
├── package.json
├── src
└── yarn.lock

Your aws-sdk.js mock file can contain the following:

module.exports.CognitoIdentityServiceProvider = jest.fn(() => ({
    listUsersInGroup: mockListUsersInGroup,
}))

const mockListUsersInGroup = jest.fn((params) => ({
    // You can replace the resolved value.
    promise: () => Promise.resolve({}),
}))

Upvotes: 2

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