Testing Validation Errors with APIs

So all I am trying to do is test my API login endpoint to test that the process of validation actually works. As usual, in the implementation, I deliberately pass in wrong values or empty values and then test to see if the errors are thrown. Below is my current implementation:

Test Class/Method:

    public function test_user_can_not_sign_up_on_validation_error()
    {
        $this->withoutExceptionHandling();

        $user = [
            'firstname' => 'Dela',
            'lastname' => 'Akakpo',
            'date_of_birth' => '1996-01-01',
            'gender' => 'Male',
            'phone_number' => '0209059199',
            'address' => 'Madina Accra',
            'email' => '',
            'password' => 'password',
            'country_id' => Country::factory()->create()->id
        ];

        $response = $this->postJson(route('api.register'),  $user);

        $response->assertStatus(Response::HTTP_UNPROCESSABLE_ENTITY);
        $response->assertJsonValidationErrors('email');
    }

As seen above, the email field is empty and hence I am testing to see if the validation error has the email value in it using the assertJsonValidationErrors method.

Unfortunately, this does not work. It throws the Illuminate\Validation\ValidationException.

Stack trace below:

   FAIL  Tests\Feature\Auth\RegistrationTest
  ⨯ user can not sign up on validation error

  ---

  • Tests\Feature\Auth\RegistrationTest > user can not sign up on validation error
   Illuminate\Validation\ValidationException 

  The given data was invalid.

  at vendor/laravel/framework/src/Illuminate/Foundation/Http/FormRequest.php:138
    134▕      * @throws \Illuminate\Validation\ValidationException
    135▕      */
    136▕     protected function failedValidation(Validator $validator)
    137▕     {
  ➜ 138▕         throw (new ValidationException($validator))
    139▕                     ->errorBag($this->errorBag)
    140▕                     ->redirectTo($this->getRedirectUrl());
    141▕     }
    142▕ 

      +17 vendor frames 
  18  app/Http/Middleware/LogRequests.php:20
      Illuminate\Pipeline\Pipeline::Illuminate\Pipeline\{closure}(Object(Illuminate\Http\Request))

      +31 vendor frames 
  50  tests/Feature/Auth/RegistrationTest.php:70
      Illuminate\Foundation\Testing\TestCase::postJson("https://afap-ims.test/api/v1/register")


  Tests:  1 failed
  Time:   0.38s