Example of validation test with Laravel using custom assertion to avoid code repetition

CreatePageTest.php

<?php 

//......

class CreatePageTest extends TestCase

    //.....
  
    /** @test */
    function meta_description_is_required()
    {
        $this->assertAdminCannotCreatePageWithout('meta_description');
    }

    protected function assertAdminCannotCreatePageWithout($field)
    {
        $this->assertAdminCannotCreatePageWith([$field => null]);
    }

    protected function assertAdminCannotCreatePageWith(array $invalidFields, array $additionalData = [])
    {
        $this->handleValidationExceptions();

        $this->actingAs($this->anAdmin())
            ->post('admin/pages', $this->withData($invalidFields, $additionalData))
            ->assertSessionHasErrors(array_keys($invalidFields));

        $this->assertDatabaseEmpty('pages');
    }

    protected function withData(array $custom = [], array $additional = [])
    {
        return array_merge($this->defaultData(), $custom, $additional);
    }

    protected function defaultData()
    {
        return $this->defaultData;
    }

}

This is based on an idea @clemir had while working together on a project. I tweaked the code and added a few extras.

Usage:

For required fields:

$this->assertAdminCannotCreatePageWithout($requiredFieldHere);

For other types of validation:

$this->assertAdminCannotCreatePageWith([$invalidField => $invalidData]);

To test validations that depends on other (valid) fields:

$this->assertAdminCannotCreatePageWith([$invalidField => $invalidData], ['valid field' => 'valid data']);

(The above is useful when testing rules that depend on other fields like requiredIf).

Of course you need to adapt assertAdminCannotCreatePageWith depending on the action and module you are testing, the convention I use is:

assert[ROLE_HERE]Cannot[ACTION_VERB][MODULE_NAME][With|Without]

• Overwrite the default method or set the default property in order to set the default fields.
• Test that the table is empty or has not been changed at the end.
• anAdmin is just a helper that returns an admin user created with a model factory.