Add mirror previous transitions

PreviousWorkflowTransitionCompilerPass.php

<?php

namespace App\Application\Symfony\CompilerPass;

use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Definition;
use Symfony\Component\Workflow;

class PreviousWorkflowTransitionCompilerPass implements CompilerPassInterface
{
    const PREFIX = 'previous_';
    public function process(ContainerBuilder $container)
    {
        $workflowDefinitionIds = $container->findTaggedServiceIds('workflow.definition');

        foreach ($workflowDefinitionIds as $serviceId => $tags) {
            $this->addPreviousTransitions($container->getDefinition($serviceId), reset($tags)['type']);
        }
    }

    private function addPreviousTransitions(Definition $definition, string $type)
    {
        // This method supports only state machine workflow.
        if ($type !== 'state_machine') {
            return;
        }

        /** @var Definition[] $transitionsDefinitions */
        $transitionsDefinitions = $definition->getArgument(1);
        $result = [];

        foreach ($transitionsDefinitions as $transitionDefinition) {
            $result[] = $transitionDefinition;
            $args = $transitionDefinition->getArguments();
            $result[] = new Definition(Workflow\Transition::class, [
                self::PREFIX . $args[0],
                $args[2],
                $args[1]
            ]);
        }

        $definition->setArgument(1, $result);
    }
}

PreviousWorkflowTransitionCompilerPassTest.php

<?php

namespace App\Tests\Application\Symfony\CompilerPass;

use App\Application\Symfony\CompilerPass\PreviousWorkflowTransitionCompilerPass;
use PHPUnit\Framework\TestCase;
use Symfony\Component\DependencyInjection\ChildDefinition;
use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Definition;
use Symfony\Component\DependencyInjection\Reference;
use Symfony\Component\Workflow;

class PreviousWorkflowTransitionCompilerPassTest extends TestCase
{
    public function testItIsASymfonyCompilerPass()
    {
        $pass = new PreviousWorkflowTransitionCompilerPass();
        $this->assertInstanceOf(CompilerPassInterface::class, $pass);
    }

    public function testItAddsTransitionsToWorkflow()
    {
        // Some of this is extracted from FrameworkExtension::registerWorkflowConfiguration
        $container = new ContainerBuilder();
        $transitionDefinition = new Definition(Workflow\Transition::class, ['to_bar', 'foo', 'bar']);
        $definitionDefinition = new Definition(Workflow\Definition::class);
        $definitionDefinition->setPublic(false);
        $definitionDefinition->addArgument(['foo', 'bar']);          // Places
        $definitionDefinition->addArgument([$transitionDefinition]); // Transitions
        $definitionDefinition->addTag('workflow.definition', array(
            'name' => 'adp_lead',
            'type' => 'state_machine',
            'marking_store' => 'single_state',
        ));
        $definitionDefinition->addArgument('foo');                   // initial place

        $markingStoreDefinition = new Definition(Workflow\MarkingStore\SingleStateMarkingStore::class, [
            'state'
        ]);

        $workflowId = sprintf('%s.%s', 'state_machine', 'adp_lead');
        $workflowDefinition = new Definition(Workflow\Workflow::class, [
            new Reference(sprintf('%s.definition', $workflowId)),
            $markingStoreDefinition,
            null,
            'adp_lead'
        ]);
        $workflowDefinition->setPublic(true);
        $container->setDefinition($workflowId, $workflowDefinition);
        $container->setDefinition(sprintf('%s.definition', $workflowId), $definitionDefinition);

        $container->addCompilerPass(new PreviousWorkflowTransitionCompilerPass());
        $container->compile();

        $object = new Foo();
        $container->get($workflowId)->apply($object, 'to_bar');
        $this->assertEquals('bar', $object->getState());

        $container->get($workflowId)->apply($object, PreviousWorkflowTransitionCompilerPass::PREFIX . 'to_bar');
        $this->assertEquals('foo', $object->getState());
    }
}

class Foo
{
    private $state;

    public function __construct()
    {
        $this->state = 'foo';
    }

    public function setState($state)
    {
        $this->state = $state;
    }

    public function getState()
    {
        return $this->state;
    }
}