Wim Leers · Lauri Timmanee
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityValidationTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityValidationTestBase.php

+  /**
+   * Tests validation of config entity's label.
+   *
+   * @see \Drupal\Core\Entity\EntityInterface::label()
+   * @see \Drupal\Core\Entity\EntityBase::label()
+   */
+  public function testLabelValidation(): void {
+    // Some entity types are labelless:
+    // - \Drupal\Core\Entity\Entity\EntityFormDisplay
+    // - \Drupal\Core\Entity\Entity\EntityViewDisplay
+    // - \Drupal\language\Entity\ContentLanguageSettings
+    // - \Drupal\rest\Entity\RestResourceConfig
+    if ($this->entity->label() === NULL) {
+      $this->markTestSkipped();
+    }
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityValidationTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityValidationTestBase.php
+    }
+    // @todo Remove this in https://www.drupal.org/i/3231354.
+    if ($this->entity->getEntityType()->id() === 'editor') {
+      $this->markTestSkipped();
+    }
+    // @todo Remove this in https://www.drupal.org/i/2939931.
+    if ($this->entity instanceof LayoutBuilderEntityViewDisplay) {
+      $this->markTestSkipped();
+    }
+    if ($this->entity->getEntityType()->getKey('label') === $this->entity->getEntityType()->getKey('id')) {
+      $this->markTestSkipped('This entity type uses the ID as the label; a labelless entity is hence impossible.');
+    }
+    $label_property = $this->entity->getEntityType()->getKey('label');
+    if ($label_property === FALSE && !method_exists($this, 'removeLabel')) {
+      throw new \LogicException(sprintf('Please implement a removeLabel() method to allow testing a labelless %s.', (string) $this->entity->getEntityType()->getSingularLabel()));
+    }
--- a/core/modules/editor/tests/src/Kernel/EditorValidationTest.php
+++ b/core/modules/editor/tests/src/Kernel/EditorValidationTest.php
    $this->assertValidationErrors(['editor' => "The 'non_existent' plugin does not exist."]);
  }

+  /**
+   * {@inheritdoc}
+   */
+  public function testLabelValidation(): void {
+    // @todo Remove this override in https://www.drupal.org/i/3231354. The label of Editor entities is dynamically computed: it's retrieved from the associated FilterFormat entity. That issue will change this.
--- a/core/config/schema/core.data_types.schema.yml
+++ b/core/config/schema/core.data_types.schema.yml
  label: 'Mail'
  mapping:
    subject:
-      type: label
+      type: required_label
--- a/core/config/schema/core.entity.schema.yml
+++ b/core/config/schema/core.entity.schema.yml
  label: 'Timestamp ago display format settings'
  mapping:
    future_format:
-      type: label
+      type: required_label
      label: 'Future format'
    past_format:
-      type: label
+      type: required_label
--- a/core/modules/views/config/schema/views.schema.yml
+++ b/core/modules/views/config/schema/views.schema.yml
          # @see \Drupal\views_ui\ViewAddForm::form()
          max: 128
    label:
-      type: label
+      type: required_label