为什么测试中的spyOn函数不能与sendGrid一起使用？

Question

我正在使用Typescript用graphql-yoga和pyramida设置graphql服务器。用户注册后，带有验证链接的电子邮件将发送到给定的电子邮件地址。一切工作正常，但我想在重构功能之前编写一个针对突变的测试，该功能检查是否未调用SendGrid的“发送”功能。

我尝试使用spyOn监视该函数，但是得到的只是一个错误，原因是在测试环境中未提供SendGrid的API密钥。

我以前使用过spyOn，并且可以正常工作，尽管这是我第一次在Typescript中使用笑话。

注册突变

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: '[email protected]',
            to: `${user.email}`,
            subject: 'Account validation',
            text: `validation Id: ${registration.id}`
        };
        await sgMail.send(emailData);

        return user;
    }
}

尝试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: "[email protected]",
            password: "anyPassword"
        }
    };

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

运行测试给了我：

Error: GraphQL error: Unauthorized

注释出send的函数调用并运行测试给了我：

Error: expect(spy).toHaveBeenCalled()

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

Answer 1

您没有以正确的方式嘲笑@sendgrid/mail模块。这就是错误发生的原因。这是不使用GraphQL测试客户端的解决方案。但是，在正确模拟GraphQL模块之后，您可以使用GraphQL测试客户端来测试GraphQL解析器和@sendgrid/mail架构。

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: '[email protected]' };
    const registration = { id: '1' };
    const emailData = {
      from: '[email protected]',
      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: '[email protected]' });
      expect(sgMail.send).toBeCalledWith({
        from: '[email protected]',
        to: '[email protected]',
        subject: 'Account validation',
        text: `validation Id: 1`
      });
    });
  });
});

单元测试结果覆盖率100％：

 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

这里是完整的演示：https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/56379585