ModerationStateWidget depends on EntityTypeInterface::getBundleEntityType despite content moderation supporting entity types without a bundle.

Good spot!

It's only recently we've started supporting non-bundle entity types, so we really need to increase the testing on this. One of the main outstanding things if you can't enable moderation on a non-bundle entity type, because the current UI is within the bundle settings. So interested to know how you're hitting this. However, this will change once #2843083: Select entity type / bundle in workflow settings gets in, which will allow you to enable moderation on non-bundle entity types.

Here's a patch for this.

+++ b/core/modules/content_moderation/src/Tests/ModerationFormTest.php
@@ -1,6 +1,7 @@
 namespace Drupal\content_moderation\Tests;
+use Drupal\workflows\Entity\Workflow;

Super nit, missing newline between namespace and use, hopefully can be fixed on commit.

Otherwise +1 to more comprehensive testing for non-config bundles. Diff makes perfect sense, no need to get an instance of the bundle for an exception only.

adding newline ---> #5

Reroll and back to RTBC.

+++ b/core/modules/content_moderation/src/Plugin/Field/FieldWidget/ModerationStateWidget.php
@@ -109,8 +109,6 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
 
-    /* @var \Drupal\Core\Config\Entity\ConfigEntityInterface $bundle_entity */
-    $bundle_entity = $this->entityTypeManager->getStorage($entity->getEntityType()->getBundleEntityType())->load($entity->bundle());
     if (!$this->moderationInformation->isModeratedEntity($entity)) {
       // @todo https://www.drupal.org/node/2779933 write a test for this.
       return $element + ['#access' => FALSE];
@@ -119,7 +117,7 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen

@@ -119,7 +117,7 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
     $workflow = $this->moderationInformation->getWorkflowForEntity($entity);
     $default = $items->get($delta)->value ? $workflow->getState($items->get($delta)->value) : $workflow->getInitialState();
     if (!$default) {
-      throw new \UnexpectedValueException(sprintf('The %s bundle has an invalid moderation state configuration, moderation states are enabled but no default is set.', $bundle_entity->label()));
+      throw new \UnexpectedValueException('Invalid moderation state configuration, moderation states are enabled but no default is set.');
     }

Do we want to keep the more specific error message when there's a bundle? Or at least add the entity type to the message?

There is no situation when this exception will be triggered.

$default = $items->get($delta)->value ? $workflow->getState($items->get($delta)->value) : $workflow->getInitialState();

In the true part of the ternary, the workflow entity already throws an exception if the state doesn't exist, in the false part now that we have the required_states feature on the ContentModeration workflow type, there will always be something set.

So, this is actually totally safe to remove.

I also need this backported to 8.3. Attached.

Good solution to #11.

Queued an 8.3.x test for #13.

I like that much better. Committed/pushed to 8.4.x and cherry-picked to 8.3.x, thanks!

Neither the 8.4.x nor 8.3.x patches applied to me, but did a local re-roll prior to commit.

Something wen't wrong here with 8.3.x, see:
https://www.drupal.org/pift-ci-job/668343
https://www.drupal.org/pift-ci-job/668344
https://www.drupal.org/pift-ci-job/668345
https://www.drupal.org/pift-ci-job/668346

That's strange because entity_test_mulrevpub exists in 8.3.x: http://cgit.drupalcode.org/drupal/tree/core/modules/system/tests/modules...

It is intermittent, 30% failure rate judging by https://www.drupal.org/node/3060/qa.
Edit: scratch that, all those "tested on commit" failed.

I've reverted this on 8.3.x

This might be related to #2864008: Convert web tests to browser tests for content_moderation module, at least let's run it past DrupalCI now I've cherry-picked that commit.

Here's an 8.3.x backport.

Looks great. All the changes are the same as the patch for 8.4.x which I confirmed by applying and committing the changes locally and then checking out the 8.4.x version of the test.

Committed/pushed to 8.3.x, thanks!