为什么测试中的 spyOn 功能不能与 sendGrid 一起使用？

Question

I am setting up a graphql server with graphql-yoga and `prisma using Typescript. When a user signs up, an email with a link for validation will be sent to the given email address. Everything is working fine, but i want to write a test for the mutation before refactoring the functionality, which checks if the 'send' function of SendGrid hast been called.

I tried spying on the function with jest.spyOn , but all I get is an error, that comes from not providing an API key for SendGrid in the tesing environment.

I have used spyOn before, and it worked, though this is the first time I am using jest with Typescript.

SignUp Mutation

import * as sgMail from '@sendgrid/mail';

sgMail.setApiKey(process.env.MAIL_API_KEY);

export const Mutation = {
    async signUpUser(parent, { data }, { prisma }, info) {
        [...]
        const emailData = {
            from: 'test@test.de',
            to: `${user.email}`,
            subject: 'Account validation',
            text: `validation Id: ${registration.id}`
        };
        await sgMail.send(emailData);

        return user;
    }
}

Trying spyOn

import * as sgMail from '@sendgrid/mail';

const signUpUserMutation = gql`
    mutation($data: ValidationInput) {
        signUpUser (data: $data) {
            id
            email
        }
    }
`;

it('should send a registration email, with a link, containing the id of the registration', async () => {
    spyOn(sgMail, "send").and.returnValue(Promise.resolve('Success'));
    const variables = {
        data: {
            email: "test@test.de",
            password: "anyPassword"
        }
    };

    await client.mutate({ mutation: signUpUserMutation, variables});
    expect(sgMail.send).toHaveBeenCalled();
});

Running the test gives me:

Error: GraphQL error: Unauthorized

Commenting out the function call of send in the mutation and running the test gives me:

Error: expect(spy).toHaveBeenCalled()

Expected spy to have been called, but it was not called.

Answer 1

You don't mock @sendgrid/mail module in a correct way. That's why the error happened. Here is the solution without using GraphQL test client. But you can use GraphQL test client to test your GraphQL resolver and GraphQL Schema after you mock @sendgrid/mail module correctly.

mutations.ts :

import * as sgMail from '@sendgrid/mail';

sgMail.setApiKey(process.env.MAIL_API_KEY || '');

export const Mutation = {
  async signUpUser(parent, { data }, { prisma }, info) {
    const user = { email: 'example@gmail.com' };
    const registration = { id: '1' };
    const emailData = {
      from: 'test@test.de',
      to: `${user.email}`,
      subject: 'Account validation',
      text: `validation Id: ${registration.id}`
    };
    await sgMail.send(emailData);

    return user;
  }
};

mutations.spec.ts :

import { Mutation } from './mutations';
import * as sgMail from '@sendgrid/mail';
import { RequestResponse } from 'request';

jest.mock('@sendgrid/mail', () => {
  return {
    setApiKey: jest.fn(),
    send: jest.fn()
  };
});

describe('Mutation', () => {
  describe('#signUpUser', () => {
    beforeEach(() => {
      jest.resetAllMocks();
    });
    it('should send a registration email, with a link, containing the id of the registration', async () => {
      (sgMail.send as jest.MockedFunction<typeof sgMail.send>).mockResolvedValueOnce([{} as RequestResponse, {}]);
      const actualValue = await Mutation.signUpUser({}, { data: {} }, { prisma: {} }, {});
      expect(actualValue).toEqual({ email: 'example@gmail.com' });
      expect(sgMail.send).toBeCalledWith({
        from: 'test@test.de',
        to: 'example@gmail.com',
        subject: 'Account validation',
        text: `validation Id: 1`
      });
    });
  });
});

Unit test result with 100% coverage:

 PASS  src/stackoverflow/56379585/mutations.spec.ts (12.419s)
  Mutation
    #signUpUser
      ✓ should send a registration email, with a link, containing the id of the registration (23ms)

--------------|----------|----------|----------|----------|-------------------|
File          |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
--------------|----------|----------|----------|----------|-------------------|
All files     |      100 |      100 |      100 |      100 |                   |
 mutations.ts |      100 |      100 |      100 |      100 |                   |
--------------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        14.315s

Here is the completed demo: https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/56379585

Answer 2

I have the exact same problem but without Graphql, for me it's a simple function:

const sgMail = require('@sendgrid/mail');
sgMail.setApiKey(process.env.SENDGRID_API_KEY);

const simplemail = () => {
  const msg = {
    to: 'receiver@mail.com',
    from: 'sender@test.com',
    subject: 'TEST Sendgrid with SendGrid is Fun',
    text: 'and easy to do anywhere, even with Node.js',
    html: '<strong>and easy to do anywhere, even with Node.js</strong>',
    mail_settings: {
      sandbox_mode: {
        enable: true,
      },
    },
  };
  (async () => {
    try {
      console.log(await sgMail.send(msg));
    } catch (err) {
      console.error(err.toString());
    }
  })();
};

export default simplemail;

i would like to test it with jest and mock sendgrid it but how ?