A chatGPT conversation about test frameworks
Tags: gpt3, cypress, jest, nestjs
Published: 2023-02-16 21:40:13

Me: Can you describe tools for adding scripts within an application built on nest.js for the purpose of adding dummy data to a connected database?
***
GPT:
Sure! Nest.js is a popular framework for building server-side applications using Node.js. To add dummy data to a connected database in a Nest.js application, you can use a combination of Nest.js built-in functionality and third-party packages.

Here are some tools you can use:

1.  Nest.js CLI: The Nest.js CLI is a command-line interface that allows you to generate Nest.js modules, controllers, and services. You can use the CLI to generate a script that will populate your database with dummy data. To do this, run the command `nest generate script` and provide a name for your script.
    
2.  TypeORM: TypeORM is an Object Relational Mapping (ORM) library for TypeScript and JavaScript. It provides a way to interact with your database using TypeScript classes, making it easier to work with your data in a type-safe way. TypeORM includes a powerful data seeding feature that allows you to populate your database with dummy data. You can use TypeORM's data seeding feature in your Nest.js application to add dummy data to your connected database.
    
3.  Faker.js: Faker.js is a JavaScript library for generating fake data. It provides a wide range of functions that can generate realistic data such as names, addresses, and dates. You can use Faker.js in your Nest.js application to generate dummy data for your database.
    

To use these tools together, you can create a script that uses Faker.js to generate fake data, and then use TypeORM to insert that data into your database. Here's an example script that uses these tools:

```typescript
import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import * as faker from 'faker';
import { User } from './user.entity';

@Injectable()
export class DummyDataService {
  constructor(
    @InjectRepository(User)
    private readonly userRepository: Repository<User>,
  ) {}

  async createDummyData() {
    for (let i = 0; i < 10; i++) {
      const user = new User();
      user.name = faker.name.findName();
      user.email = faker.internet.email();
      user.password = faker.internet.password();
      await this.userRepository.save(user);
    }
  }
}

```

In this example, the script generates ten fake users using Faker.js, and then saves them to the database using TypeORM's `save` method. You can then run this script using the Nest.js CLI by running the command `nest run <script-name>`.
***
ME:
Is it possible to do this using the test frameworks nest.js makes available?
***
GPT:
Yes, it is possible to use Nest.js testing framework to add dummy data to a connected database. In fact, using the testing framework can make it easier to write and run tests that require dummy data.

Here are the steps to add dummy data to a connected database using Nest.js testing framework:

1.  Create a Nest.js testing module: Create a Nest.js testing module that imports the necessary modules, controllers, and services to work with your database. You can use the `@nestjs/testing` module to create a testing module.

```typescript
import { Test, TestingModule } from '@nestjs/testing';
import { TypeOrmModule } from '@nestjs/typeorm';
import { User } from './user.entity';
import { UserService } from './user.service';

describe('UserModule', () => {
  let module: TestingModule;

  beforeAll(async () => {
    module = await Test.createTestingModule({
      imports: [TypeOrmModule.forRoot(), TypeOrmModule.forFeature([User])],
      providers: [UserService],
      controllers: [UserController],
    }).compile();
  });

  afterAll(async () => {
    await module.close();
  });

  it('should be defined', () => {
    const controller: UserController = module.get<UserController>(UserController);
    expect(controller).toBeDefined();
  });
});
```

2.  Use TypeORM to add dummy data: Once you have created a testing module, you can use TypeORM to add dummy data to your connected database. You can use the `getRepository` method to get access to the repository for the entity you want to add data to, and then use the `save` method to save the data to the database.

```typescript
import { Test, TestingModule } from '@nestjs/testing';
import { TypeOrmModule } from '@nestjs/typeorm';
import { User } from './user.entity';
import { UserService } from './user.service';

describe('UserModule', () => {
  let module: TestingModule;

  beforeAll(async () => {
    module = await Test.createTestingModule({
      imports: [TypeOrmModule.forRoot(), TypeOrmModule.forFeature([User])],
      providers: [UserService],
      controllers: [UserController],
    }).compile();

    const userRepository = module.get('UserRepository');
    await userRepository.save({ name: 'John Doe', email: 'johndoe@example.com' });
  });

  afterAll(async () => {
    await module.close();
  });

  it('should be defined', () => {
    const controller: UserController = module.get<UserController>(UserController);
    expect(controller).toBeDefined();
  });
});
```

In this example, the `beforeAll` hook is used to add a new user to the database using TypeORM's `save` method. The `afterAll` hook is used to close the testing module after the tests have run.

Note that you can also use other third-party libraries, such as `Faker.js`, to generate dummy data to use in your tests. Once you have generated the data, you can use TypeORM to save it to the database in a similar way to the example above.

In summary, Nest.js testing framework provides you with a way to add dummy data to a connected database in your tests. You can use TypeORM or other third-party libraries to generate the data, and then use the repository's `save` method to save it to the database.
***

ME: Can we implement something similar using the mongoose module?

GPT:
Yes, you can implement something similar using the Mongoose module in Nest.js.

Here's an example of how you can create a test module in Nest.js that uses Mongoose to connect to a MongoDB database and add dummy data:

```typescript
import { Test, TestingModule } from '@nestjs/testing';
import { MongooseModule } from '@nestjs/mongoose';
import { UserController } from './user.controller';
import { UserService } from './user.service';
import { UserSchema } from './user.schema';
import { getModelToken } from '@nestjs/mongoose';

describe('User Module', () => {
  let app: TestingModule;
  let userService: UserService;
  let userModel: any;

  beforeAll(async () => {
    app = await Test.createTestingModule({
      imports: [MongooseModule.forRoot('mongodb://localhost/nest-test'), MongooseModule.forFeature([{ name: 'User', schema: UserSchema }])],
      controllers: [UserController],
      providers: [UserService],
    }).compile();

    userService = app.get<UserService>(UserService);
    userModel = app.get(getModelToken('User'));
  });

  afterAll(async () => {
    await userModel.deleteMany({});
    await app.close();
  });

  describe('dummy data', () => {
    it('should create a new user', async () => {
      const userData = { name: 'John Doe', email: 'johndoe@example.com' };
      const createdUser = await userService.createUser(userData);

      expect(createdUser.name).toEqual(userData.name);
      expect(createdUser.email).toEqual(userData.email);
    });
  });
});

```

In this example, we use the `MongooseModule` to connect to a MongoDB database and provide the `UserSchema` to `MongooseModule.forFeature`. We then use `getModelToken` to get access to the `User` model, and use it to create a new user by calling the `createUser` method of the `UserService`.

Note that in the `afterAll` hook, we use `userModel.deleteMany({})` to delete all documents in the `User` collection after running the tests.

In summary, you can use the Mongoose module in Nest.js to add dummy data to a MongoDB database. You can create a test module that imports the necessary modules, controllers, and services to work with your database, and then use the Mongoose model to create and save dummy data.
***
ME: Is it possible to test the frontend application connected to the API while these tests are running?
***
GPT:
Yes, it is possible to test a frontend application that is connected to an API being tested in Nest.js. You can use tools like Cypress or Jest to write end-to-end (E2E) tests that simulate user interactions with the frontend application and verify the responses from the API.

Here is an example of how you can write an E2E test in Cypress that tests a frontend application connected to a Nest.js API:

```javascript
describe('User API', () => {
  it('should create a new user', () => {
    cy.request('POST', '/users', {
      name: 'John Doe',
      email: 'johndoe@example.com',
    }).then((response) => {
      expect(response.status).to.eq(201);
      expect(response.body.name).to.eq('John Doe');
      expect(response.body.email).to.eq('johndoe@example.com');
    });

    cy.visit('/users');

    cy.get('table tbody tr').should('have.length', 1);
    cy.get('table tbody tr td:nth-child(1)').should('contain', 'John Doe');
    cy.get('table tbody tr td:nth-child(2)').should('contain', 'johndoe@example.com');
  });
});
```

In this example, we use `cy.request` to make a POST request to create a new user in the Nest.js API. We then use `cy.visit` to load the frontend application, and use `cy.get` to select elements on the page and verify that the new user is displayed correctly.

Note that the Nest.js API and the frontend application must be running during the test for this to work. You can use tools like concurrently or npm-run-all to run both the Nest.js server and the frontend application together during development and testing.

In summary, it is possible to test a frontend application connected to a Nest.js API using E2E tests in tools like Cypress or Jest. You can simulate user interactions with the frontend application and verify the responses from the API to ensure that both the frontend and backend are working correctly.
***
ME: Am I to understand that cypress is used in conjunction with jest?
***
GPT:
No, Cypress and Jest are two different testing frameworks that can be used independently of each other. Both tools have their own unique features and capabilities that make them suitable for different types of testing.

Jest is a JavaScript testing framework that is primarily used for unit testing, integration testing, and snapshot testing. It is designed to be simple and easy to use, and it provides features like test runners, assertions, mocking, and coverage reporting.

Cypress, on the other hand, is an end-to-end (E2E) testing framework that is used for testing the entire application stack, including the frontend and backend. It provides a range of features for simulating user interactions, testing UI components, and verifying API responses.

While you can use Jest to write E2E tests using tools like Puppeteer or Playwright, Cypress is specifically designed for this type of testing and offers many advantages, such as fast test execution, built-in debugging, and a user-friendly interface.

In summary, Cypress and Jest are two different testing frameworks that can be used independently of each other, depending on the testing needs of your application.
***
ME:
Can you show me how you would generate tests for the following module using cypress:
```typescript
import {
  Controller,
  Get,
  Post,
  Body,
  Patch,
  Param,
  Delete,
  Query,
} from '@nestjs/common'
import { PaginationParams } from '../utils/entities/paginationParams'
import { CreatePatientDto } from './dto/create-patient.dto'
import { UpdatePatientDto } from './dto/update-patient.dto'
import { PatientsService } from './patients.service'

@Controller('patients')
export class PatientsController {
  constructor(private readonly patientsService: PatientsService) {}

  @Post()
  create(@Body() createPatientDto: CreatePatientDto) {
    return this.patientsService.create(createPatientDto)
  }

  @Get()
  findAll(@Query() {skip, limit}: PaginationParams, @Query() params?: any) {
    return this.patientsService.findAll(skip, limit, params);
  }

  @Get(':id')
  findOne(@Param('id') id: string) {
    return this.patientsService.findOne(id)
  }

  @Get('/provider/:provider_id')
  findByProviderId(@Param('provider_id') id: string, @Query() {skip, limit}: PaginationParams, @Query() filters?: any, @Query() sorts?: any) {
    return this.patientsService.findByProviderId(id, skip, limit, filters);
  }

  // search for patients by name
  @Get('/search/:name')
  search(@Param('name') name, @Query() {skip, limit}: PaginationParams, @Query() filters?: any) {
    return this.patientsService.search(name, skip, limit, filters);
  } 

  @Patch(':id')
  update(@Param('id') id: string, @Body() updatePatientDto: UpdatePatientDto) {
    return this.patientsService.update(id, updatePatientDto)
  }

  @Delete(':id')
  remove(@Param('id') id: string) {
    return this.patientsService.remove(+id)
  }
}
```
***
GPT:
Certainly! Here's an example of how you could write Cypress tests for this `PatientsController` module:
```typescript
describe('PatientsController', () => {
  beforeEach(() => {
    cy.visit('http://localhost:3000/patients')
  })

  it('should create a new patient', () => {
    const patient = {
      name: 'John Doe',
      age: 30,
      gender: 'Male',
      email: 'johndoe@example.com',
    }

    cy.get('button#add-patient').click()
    cy.get('input#name').type(patient.name)
    cy.get('input#age').type(patient.age)
    cy.get('select#gender').select(patient.gender)
    cy.get('input#email').type(patient.email)
    cy.get('button#save-patient').click()

    cy.get('table tbody tr').should('have.length', 1)
    cy.get('table tbody tr td:nth-child(1)').should('contain', patient.name)
    cy.get('table tbody tr td:nth-child(2)').should('contain', patient.age)
    cy.get('table tbody tr td:nth-child(3)').should('contain', patient.gender)
    cy.get('table tbody tr td:nth-child(4)').should('contain', patient.email)
  })

  it('should update an existing patient', () => {
    const patient = {
      name: 'Jane Doe',
      age: 35,
      gender: 'Female',
      email: 'janedoe@example.com',
    }

    cy.get('table tbody tr td:nth-child(1)').should('contain', 'John Doe')
    cy.get('table tbody tr td:nth-child(2)').should('contain', '30')
    cy.get('table tbody tr td:nth-child(3)').should('contain', 'Male')
    cy.get('table tbody tr td:nth-child(4)').should('contain', 'johndoe@example.com')
    cy.get('table tbody tr td:nth-child(5) button#edit-patient').click()

    cy.get('input#name').clear().type(patient.name)
    cy.get('input#age').clear().type(patient.age)
    cy.get('select#gender').select(patient.gender)
    cy.get('input#email').clear().type(patient.email)
    cy.get('button#save-patient').click()

    cy.get('table tbody tr td:nth-child(1)').should('contain', patient.name)
    cy.get('table tbody tr td:nth-child(2)').should('contain', patient.age)
    cy.get('table tbody tr td:nth-child(3)').should('contain', patient.gender)
    cy.get('table tbody tr td:nth-child(
```
[ stopped generating in the middle ]
***
ME: I'm getting the idea. So cypress can submit requests, and interact with UI elements.
***
GPT: Yes, that's correct! Cypress can simulate user interactions and submit requests, as well as assert on the state of the UI and the responses received from the API. This allows you to test your frontend and backend together in an end-to-end fashion, and verify that they are working together correctly to deliver the expected functionality to the user.
***
ME: Wow, it seems to make more sense to learn this than jest and puppeteer. Any thoughts?
***
GPT: It really depends on what you're trying to achieve and what you're most comfortable with. Jest and Puppeteer are also great tools for testing, and they have their own strengths and weaknesses.

Jest is a popular testing framework that is used for writing unit and integration tests. It has a large and active community, and provides a lot of features out of the box, such as mocking, coverage reporting, and snapshot testing. If you're primarily interested in testing your backend logic and APIs, Jest might be a good fit for you.

Puppeteer, on the other hand, is a Node.js library that provides a high-level API for controlling a headless Chrome or Chromium browser. It's great for testing web applications, as it allows you to simulate user interactions, take screenshots, and test the UI in a way that is very similar to how a user would interact with the app. If you're interested in testing the front-end part of your application, Puppeteer might be a better fit for you.

Cypress is also a great tool for testing web applications, and it has some advantages over Jest and Puppeteer. It's designed to make end-to-end testing easy and intuitive, and provides a lot of useful features out of the box, such as time travel debugging, automatic waiting, and network stubbing. It also has a very simple and easy-to-use API, and provides a lot of built-in assertions that make it easy to write expressive and readable tests. If you're looking for a tool that can help you test your full-stack application in a user-centric way, Cypress might be a good fit for you.

Ultimately, the choice of tool will depend on your specific requirements, and what you're most comfortable with. You might want to experiment with all three tools and see which one works best for you and your team.