Add a PHPUnit assertion that an entity is valid

Now that #3224276: Move useful helper methods for working with entities from EntityKernelTestBase to a trait → is in, this method can go on Drupal\Tests\EntityTrait.

Seems pretty straightforward and do believe useful.

Going to mark but only comment would be around the comment Asserts that an entity passes entity validation. should it be

Asserts that an entity passes validation.

But don't think worth holding up.

I wrote that initially, but then I thought it's not clear -- *what* kind of validation specifically?

Thanks for reviewing!

There are existing validation checks in tests that could be converted to use this. It doesn't necessarily have to be all of them here, but:

1. We should convert at least one in this issue, otherwise the new method is dead code.

2. If we don't convert all calls here, then that should happen in one follow-up.

Converted one test.

pipeline appears to have issues

Fixed the missing param name.

> 33 Access to an undefined property
> Drupal\Tests\field\Kernel\FieldCrudTest::$entityTypeManager.

That predates this issue's changes. Also, isn't it normal for traits to reference properties they expect on the using class?

The Needs Review Queue Bot → tested this issue. It fails the Drupal core commit checks. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

Consult the Drupal Contributor Guide → to find step-by-step guides for working with issues.

Possible to convert least 1 instance to use this new function

I already had but forgot to git push.

The Needs Review Queue Bot → tested this issue. It fails the Drupal core commit checks. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

Consult the Drupal Contributor Guide → to find step-by-step guides for working with issues.

  33     Access to an undefined property                                           
         Drupal\Tests\field\Kernel\FieldCrudTest::$entityTypeManager.              

Not sure how to deal with this, as it predates this MR.