> For the complete documentation index, see [llms.txt](https://book.restfulnode.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.restfulnode.com/part-3/chapter-10/1-testing-the-request.md).

# Testing the Request

Recall how we implemented the `registerUserRequestDto`.

*File: src/requests/registerUserRequestDto.js*

```javascript
const path = require('path')
const ApiException = require('../utils/ApiException')

const fields = [
  'first_name',
  'last_name',
  'email',
  'password',
  'password_confirmation',
  'phone_number'
]

/**
 * @param Object data
 */
const registerUserRequestDto = (data) => {
  const errors = []
  fields.forEach((field) => {
    if (!(field in data)) {
      errors.push(`This DTO's property is required: ${field}.`)
    }
  })

  if (errors.length > 0) {
    throw new ApiException({
      status: 'error',
      code: 422,
      message: 'Input fields are of not the correct form.',
      data: null,
      errors
    })
  }

  return data
}

module.exports = registerUserRequestDto
```

We'll first setup our test suite.

We'll be working mainly in this file for the rest of this section.

*File: src/requests/\_\_tests\_\_/registerUserRequestDto.test.js*

```javascript
const registerUserRequestDto = require('../registerUserRequestDto')

describe('Test Suite: registerUserRequestDto', () => {
  // tests go here...
})
```

I personally always like to write at least 1 test for both a passing and failing scenario.

Of course you can always write more tests to cover more additional scenarios and edge cases . For our purposes, we'll just be sticking to writing 1 passing test and 1 failing test.

### The Passing Test

The first one is simple, let's add in all the required fields in `registerUserRequestDto` and expect what we want out of it.

```javascript
test('Request 1 - all required fields', () => {
  // 1. Arrange
  const inputRequest = {
    first_name: 'Yichen',
    last_name: 'Zhu',
    email: 'yichen@yichen.com',
    password: 'yichen-and-his-awesome-password',
    password_confirmation: 'yichen-and-his-awesome-password',
    phone_number: '1234567890'
  }

  // 2. Act
  const registerUserRequest = registerUserRequestDto(inputRequest)

  // 3. Assert
  expect(registerUserRequest).toEqual({
    first_name: 'Yichen',
    last_name: 'Zhu',
    email: 'yichen@yichen.com',
    password: 'yichen-and-his-awesome-password',
    password_confirmation: 'yichen-and-his-awesome-password',
    phone_number: '1234567890'
  })
})
```

### The Failing Test

The next test case is what happens if we don't pass the correct inputs into the `registerUserRequestDto` function. We would expect an error, and not just any error, but an `ApiException` error being thrown.

```javascript
test('Request 2 - missing input fields', () => {
  // 1. Arrange
  const inputRequest = { message: 'this is awesome!' }

  // 2. Act + 3. Assert
  expect(() => {
    registerUserRequestDto(inputRequest)
  }).toThrow(ApiException)
})
```


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