feature #30908 [Workflow] Added workflow_transition_blockers twig function (lyrixx)

This PR was merged into the 4.3-dev branch.

Discussion
----------

[Workflow] Added workflow_transition_blockers twig function

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | https://github.com/symfony/symfony-docs/pull/11268
| License       | MIT
| Doc PR        | https://github.com/symfony/symfony-docs/pull/11268

EUFOSSA

---

also related to https://github.com/symfony/symfony/issues/26689

I'm not a big fan of the current name. What should I pick?

cc @javiereguiluz

Commits
-------

a2f99757f1 [Workflow] Added workflow_transition_blockers twig function

src/Symfony/Bridge/Twig/CHANGELOG.md

@@ -5,6 +5,7 @@ CHANGELOG
 -----
 
  * added the `form_parent()` function that allows to reliably retrieve the parent form in Twig templates
+ * added the `workflow_transition_blockers()` function
 
 4.2.0
 -----

src/Symfony/Bridge/Twig/Extension/WorkflowExtension.php

@@ -13,6 +13,7 @@ namespace Symfony\Bridge\Twig\Extension;
 
 use Symfony\Component\Workflow\Registry;
 use Symfony\Component\Workflow\Transition;
+use Symfony\Component\Workflow\TransitionBlockerList;
 use Twig\Extension\AbstractExtension;
 use Twig\TwigFunction;
 
@@ -38,6 +39,7 @@ class WorkflowExtension extends AbstractExtension
             new TwigFunction('workflow_has_marked_place', [$this, 'hasMarkedPlace']),
             new TwigFunction('workflow_marked_places', [$this, 'getMarkedPlaces']),
             new TwigFunction('workflow_metadata', [$this, 'getMetadata']),
+            new TwigFunction('workflow_transition_blockers', [$this, 'buildTransitionBlockerList']),
         ];
     }
 
@@ -120,6 +122,13 @@ class WorkflowExtension extends AbstractExtension
         ;
     }
 
+    public function buildTransitionBlockerList($subject, string $transitionName, string $name = null): TransitionBlockerList
+    {
+        $workflow = $this->workflowRegistry->get($subject, $name);
+
+        return $workflow->buildTransitionBlockerList($subject, $transitionName);
+    }
+
     public function getName()
     {
         return 'workflow';

src/Symfony/Bridge/Twig/Tests/Extension/WorkflowExtensionTest.php

@@ -20,6 +20,7 @@ use Symfony\Component\Workflow\Registry;
 use Symfony\Component\Workflow\SupportStrategy\ClassInstanceSupportStrategy;
 use Symfony\Component\Workflow\SupportStrategy\InstanceOfSupportStrategy;
 use Symfony\Component\Workflow\Transition;
+use Symfony\Component\Workflow\TransitionBlockerList;
 use Symfony\Component\Workflow\Workflow;
 
 class WorkflowExtensionTest extends TestCase
@@ -110,6 +111,18 @@ class WorkflowExtensionTest extends TestCase
         $this->assertNull($this->extension->getMetadata($subject, 'not found'));
         $this->assertNull($this->extension->getMetadata($subject, 'not found', $this->t1));
     }
+
+    public function testbuildTransitionBlockerList()
+    {
+        if (!class_exists(TransitionBlockerList::class)) {
+            $this->markTestSkipped('This test requires symfony/workflow:4.1.');
+        }
+        $subject = new Subject();
+
+        $list = $this->extension->buildTransitionBlockerList($subject, 't1');
+        $this->assertInstanceOf(TransitionBlockerList::class, $list);
+        $this->assertTrue($list->isEmpty());
+    }
 }
 
 final class Subject