Bring back the simpletest-based FieldUnitTestBase until 8.2.x

Looks good to me.

We did the same in other cases (EntityUnitTestBase, still has implementations in core though, views base classes, ..), not sure if we did it for migrate or not.

Attaching a diff against 8.0.x, to be sure that we're not introducing a bug here. It's the same except the deprecation notice, entity_create() calls and the router table that was removed from installSchema().

+++ b/core/modules/field/src/Tests/FieldUnitTestBase.php
@@ -7,13 +7,18 @@
 
+use CommerceGuys\Intl\Language\LanguageInterface;
 use Drupal\Component\Utility\Unicode;

oh, missed that.

Better :)

I'm not sure core needs to move backwards on it. I'll just be the same problem in 6 months.

The main practical problem is that D.O won't let you specify which version of core to use in tests, so you have to wait for it to finish failing, and then restart the test using 8.0.x.

When 8.1.0 comes out then 8.0.x is unsupported and does not need to work anymore. So by then, it will be safe for modules to update to use the new base classes and only support 8.1 and 8.2

Yes, the testbot situation is unfortunate but not really relevant. This is about allowing contrib to easily support the two relevant minor versions.

Committed 57436e1 and pushed to 8.1.x. Thanks!

The differences to 8.0.x look totally sane...

diff --git a/core/modules/field/src/Tests/FieldUnitTestBase.php b/core/modules/field/src/Tests/FieldUnitTestBase.php
index ddcf3f9..a223d45 100644
--- a/core/modules/field/src/Tests/FieldUnitTestBase.php
+++ b/core/modules/field/src/Tests/FieldUnitTestBase.php
@@ -10,10 +10,15 @@
 use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Language\LanguageInterface;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\simpletest\KernelTestBase;
 
 /**
  * Parent class for Field API unit tests.
+ *
+ * @deprecated in Drupal 8.1.x, will be removed before Drupal 8.2.x. Use
+ *   \Drupal\Tests\field\Kernel\FieldKernelTestBase instead.
  */
 abstract class FieldUnitTestBase extends KernelTestBase {
 
@@ -50,7 +55,7 @@ protected function setUp() {
 
     $this->installEntitySchema('entity_test');
     $this->installEntitySchema('user');
-    $this->installSchema('system', ['router', 'sequences', 'key_value']);
+    $this->installSchema('system', ['sequences', 'key_value']);
 
     // Set default storage backend and configure the theme system.
     $this->installConfig(array('field', 'system'));
@@ -91,7 +96,7 @@ protected function createFieldWithStorage($suffix = '', $entity_type = 'entity_t
     $field_definition = 'field_definition' . $suffix;
 
     $this->fieldTestData->$field_name = Unicode::strtolower($this->randomMachineName() . '_field_name' . $suffix);
-    $this->fieldTestData->$field_storage = entity_create('field_storage_config', array(
+    $this->fieldTestData->$field_storage = FieldStorageConfig::create(array(
       'field_name' => $this->fieldTestData->$field_name,
       'entity_type' => $entity_type,
       'type' => 'test_field',
@@ -108,7 +113,7 @@ protected function createFieldWithStorage($suffix = '', $entity_type = 'entity_t
         'test_field_setting' => $this->randomMachineName(),
       ),
     );
-    $this->fieldTestData->$field = entity_create('field_config', $this->fieldTestData->$field_definition);
+    $this->fieldTestData->$field = FieldConfig::create($this->fieldTestData->$field_definition);
     $this->fieldTestData->$field->save();
 
     entity_get_form_display($entity_type, $bundle, 'default')