PHPUnit dataproviders to test validations in Laravel

Here an example with login.

A login should test:
- email and password are not empty
- email has a valid format
- password has at least 8 characters length

All this tests are expecting a validation message for any of this cases, basically it is the same process with different data, this is a great scenario for PHPUnit Dataproviders.

Install some authentication scaffold (optionally)

composer require laravel/breeze --dev 

Install breeze

php artisan breeze:install npm install npm run dev php artisan migrate 

Make a tests for login to validates the request.

php artisan make:test LoginValidationTest 

Here the basic test:

/** * @test * @dataProvider invalidUsersData */ public function it_tests_a_login_form_validation($invalidData, $invalidFields): void { $response = $this->post('/login', $invalidData); $response->assertSessionHasErrors($invalidFields); $this->assertDatabaseCount('users', 0); } public function invalidUsersData(): array { return [ [ ['email' => '', 'password' => ''], ['email', 'password'] ], [ ['email' => 'somethingNotValid', 'password' => 'password'], ['email'] ], [ ['email' => 'somethingNotValid', 'password' => 123], ['password'] ], ]; } 

Explanation

First the annotation for data provider is necessary, then we see that the dataProvider function returns a multidimensional array, to explain this behavior:

PHPUnit dataProviders returns a value on every iteration, the first iteration of the data provider it would set:

$invalidData = ['email' => '', 'password' => '']; $invalidFields = ['email', 'password'] 

So every subarray would return values, in this case two values to make tests on every iteration.

So the first iteration would be equals to:

public function it_tests_a_login_form_validation(): void { $response = $this->post('/login', [ 'email' => '', 'password' => '' ]); $response->assertSessionHasErrors(['email', 'password']); $this->assertDatabaseCount('users', 0); } 

So you can create any amount of cases and the method would be executed the amount of times as subarrays are present on the dataProvider function returns.