Seamlessly setup a test database within the PHPUnit + Laravel environment

.env.testing

APP_NAME="TDD"
APP_ENV=testing
APP_DEBUG=true
APP_KEY=base64:dOal46K64jWx6dQAIIKACbeMH99iqW0HryeT+3Jkoj0=
LOG_CHANNEL=stack
DB_CONNECTION=mysql
DB_HOST=mysql_test
DB_DATABASE=tdd
DB_USERNAME=sail
DB_PASSWORD=password
FILESYSTEM_DRIVER=local
QUEUE_CONNECTION=sync
SESSION_DRIVER=file
SESSION_LIFETIME=120
MAIL_MAILER=log

DatabaseSetup.php

<?php


namespace Tests;

use Illuminate\Contracts\Console\Kernel;

trait DatabaseSetup
{
    protected static $migrated = false;

    public function setupDatabase()
    {
        if ($this->isInMemory()) {
            $this->setupInMemoryDatabase();
        } else {
            $this->setupTestDatabase();
        }
    }

    protected function isInMemory()
    {
        return config('database.connections')[config('database.default')]['database'] == ':memory:';
    }

    protected function setupInMemoryDatabase()
    {
        $this->artisan('migrate:fresh --seed');
        $this->app[Kernel::class]->setArtisan(null);
    }

    protected function setupTestDatabase()
    {
        if (!static::$migrated) {
            $this->whenMigrationsChange(function() {
                $this->artisan('migrate:fresh --seed');
                $this->app[Kernel::class]->setArtisan(null);
            });
            static::$migrated = true;
        }
        $this->beginDatabaseTransaction();
    }

    public function beginDatabaseTransaction()
    {
        $database = $this->app->make('db');
        foreach ($this->connectionsToTransact() as $name) {
            $database->connection($name)->beginTransaction();
        }
        $this->beforeApplicationDestroyed(function () use ($database) {
            foreach ($this->connectionsToTransact() as $name) {
                $database->connection($name)->rollBack();
            }
        });
    }

    protected function connectionsToTransact()
    {
        return property_exists($this, 'connectionsToTransact')
            ? $this->connectionsToTransact : [null];
    }

    protected function getMigrationsMd5()
    {
        return md5(collect(glob(base_path('database/migrations/*')))
            ->map(function ($f) {
                return file_get_contents($f);
            })->implode(''));
    }

    protected function whenMigrationsChange($callback)
    {
        $md5 = $this->getMigrationsMd5();
        $path = storage_path('app/migrations_md5.txt');
        if(!file_exists($path) || ($md5 !== file_get_contents($path))) {
            $callback();
            file_put_contents($path, $md5);
        }
    }
}

phpunit.xml

<?xml version="1.0" encoding="UTF-8"?>
<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd"
         bootstrap="vendor/autoload.php"
         colors="true"
>
    <testsuites>
        <testsuite name="Unit">
            <directory suffix="Test.php">./tests/Unit</directory>
        </testsuite>
        <testsuite name="Feature">
            <directory suffix="Test.php">./tests/Feature</directory>
        </testsuite>
    </testsuites>
    <coverage processUncoveredFiles="true">
        <include>
            <directory suffix=".php">./app</directory>
        </include>
    </coverage>
    <php>
        <env name="APP_ENV" value="testing"/>
    </php>
</phpunit>

TestCase.php

<?php

namespace Tests;

use Illuminate\Foundation\Testing\TestCase as BaseTestCase;

abstract class TestCase extends BaseTestCase
{
    use CreatesApplication, DatabaseSetup;

    /**
     * Setup the test environment.
     *
     * @return void
     */
    protected function setUp(): void
    {
        parent::setUp();
        $this->setupDatabase();
    }
}