Fix tests compatibility with Drupal 9.3.x

Test failure 1:

1) Drupal\Tests\metatag\Functional\EnsureDevelWebProfilerWorks::testCustomRoute
PHPUnit\Framework\Exception: Fatal error: Class Drupal\webprofiler\Entity\Decorators\Config\ConfigEntityStorageDecorator contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (Drupal\Core\Entity\EntityStorageInterface::getEntityClass) in /var/www/html/modules/contrib/devel/webprofiler/src/Entity/Decorators/Config/ConfigEntityStorageDecorator.php on line 18

This is a bug in the WebProfiler module that comes with the Devel module.

Test failure 2:

1) Drupal\Tests\metatag\Kernel\Migrate\d7\MetatagEntitiesTest::testMetatag
PHPUnit\Framework\Exception: PHP Fatal error:  Uncaught Exception: Serialization of 'Closure' is not allowed in Standard input code:89
Stack trace:
#0 Standard input code(89): serialize(Array)
#1 Standard input code(123): __phpunit_run_isolated_test()
#2 {main}
  thrown in Standard input code on line 89
Fatal error: Uncaught Exception: Serialization of 'Closure' is not allowed in Standard input code:89
Stack trace:
#0 Standard input code(89): serialize(Array)
#1 Standard input code(123): __phpunit_run_isolated_test()
#2 {main}
  thrown in Standard input code on line 89

I think this refers to lines like this:

    $this->assertSame(serialize($expected), $node->field_metatag->value);

Maybe that should unserialize the node value and compare it against the raw array, i.e. turning the comparison backwards?

Will this work?

Nope, that didn't work.

The test failure is being obscured by #3197324: Exception trace cannot be serialized because of closure.

The actual test failures are:

  1x: Declaring ::setUp without a void return typehint in Drupal\Tests\metatag\Kernel\Migrate\d7\MetatagEntitiesTest is deprecated in drupal:9.0.0. Typehinting will be required before drupal:10.0.0. See https://www.drupal.org/node/3114724
    1x in DrupalListener::startTest from Drupal\Tests\Listeners

  1x: The Drupal\Tests\metatag\Kernel\Migrate\d7\MetatagEntitiesTest::$modules property must be declared protected. See https://www.drupal.org/node/2909426
    1x in DrupalListener::startTest from Drupal\Tests\Listeners

Thanks to the patch from #3197324 I can actually see what the errors are.

Rerolled after #3252359 was committed.

The remaining failure, that isn't because of the Devel module, is:

1) Drupal\Tests\metatag\Kernel\Migrate\d7\MetatagEntitiesTest::testMetatag
Attempt to create a field field_event that does not exist on entity type node. (/var/www/html/core/modules/field/src/Entity/FieldConfig.php:315)
Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
-'status'
+'error'

Let's remove the Devel test entirely.

The only difference in this file is the removal of EnsureDevelWebProfilerWorks.php.

*mindblown*

Wow, thank you so much!

Committed. Thank you Eugene for solving the last puzzle piece!

For prosperity, cross-linking the issue that caused some of the tests to fail: #3095237: Migrate Drupal 7 date field "todate" value