Ensure that hook_bundle_info_alter() implementations know whether bundles are translatable

Test coverage review:

1. +++ b/core/modules/content_translation/tests/modules/a_content_translation_test/a_content_translation_test.module
   @@ -0,0 +1,13 @@
   +  \Drupal::state()->set('a_content_translation_test.translatable', !empty($bundles['entity_test_mul']['entity_test_mul']['translatable']));
   

   So this stores in the state service the value for the translatable property of the entity_test_mul entity type's only bundle that is observed in the alter hook.

2. +++ b/core/modules/content_translation/tests/src/Kernel/ContentTranslationEntityBundleInfoTest.php
   @@ -0,0 +1,61 @@
   +    $this->contentTranslationManager->setEnabled('entity_test_mul', 'entity_test_mul', TRUE);
   

   This then enables Content Translation for this entity type.

3. +++ b/core/modules/content_translation/tests/src/Kernel/ContentTranslationEntityBundleInfoTest.php
   @@ -0,0 +1,61 @@
   +    $this->assertTrue($state->get('a_content_translation_test.translatable'));
   

   This verifies that the observation stored in state is in fact TRUE because the previous point set it.

👌

Fix review:

+++ b/core/modules/content_translation/content_translation.module
@@ -60,6 +60,14 @@ function content_translation_module_implements_alter(&$implementations, $hook) {
+    // Move our hook_entity_bundle_info_alter() implementation to the top of the
+    // list, so that any other hook implementation can rely on bundles being
+    // correctly marked as translatable.
+    case 'entity_bundle_info_alter':
+      $group = $implementations['content_translation'];
+      $implementations = ['content_translation' => $group] + $implementations;

Trivial 👍

By the way: super clear issue summary!

Looks great. Adding reviewer credit.

Pushed to 8.6.x and 8.5.x.

For reasons I have not investigated, this introduced a fail in ConfigImportUITest in 8.5.x HEAD:

Action, Ban, Text and Options modules installed in the correct order.
Failed asserting that Array &0 (
    0 => 'action'
    1 => 'ban'
    2 => 'text'
    3 => 'options'
) is identical to Array &0 (
    0 => 'ban'
    1 => 'text'
    2 => 'action'
    3 => 'options'
)

https://www.drupal.org/pift-ci-job/871671

The fail only happened on 8.5.x, not 8.6.x. I confirmed that the test fails locally and that it passes when this commit is reverted.

Queued an 8.5.x test for the patch.

Yep, it fails; see above.

#19 interdiff looks good. The main change is to move the test module code out from a new module ("a_content_translation_test") and into an existing test module ("content_translation_test"). I'm not clear on why the creation of a new test module creates the 8.5.x test failure in #16, but moving the code to "content_translation_test" is cleaner anyway, so +1.

However:

+++ b/core/modules/content_translation/tests/src/Kernel/ContentTranslationEntityBundleInfoTest.php
@@ -0,0 +1,64 @@
+    // Check that, although the "a_content_translation_test" hook implementation
+    // by default would be invoked first, it still has access to the
+    // "translatable" bundle info property.

The comment needs to be changed to refer to the correct module name. Also, while it was clearer why "a_content_translation_test" would normally be invoked first (coming earlier in the alphabet than "content_translation"), it's not clear at all why "content_translation_test" would normally come before "content_translation". But sure enough, turns out the failure in the ".test" patch in #19 proves that it does. Turns out the reason is that content_translation_install() sets its module weight to 10. We should add that information to this code comment as well as add an assertion that content_translation_test has a smaller module weight than content_translation, since without that condition being met, this test would pass even without the bugfix.

RTBC if tests pass.

As I had already committed this previously, and the only changes since the revert are to tests, I committed this again to 8.6 and 8.5, despite also having been the one to re-RTBC it.