ConfigEntityValidationTestBase.php

<?php

declare (strict_types=1);
namespace Drupal\KernelTests\Core\Config;

use Drupal\Component\Utility\NestedArray;
use Drupal\Core\Config\Entity\ConfigEntityInterface;
use Drupal\Core\Config\Schema\Mapping;
use Drupal\Core\Config\TypedConfigManagerInterface;
use Drupal\Core\Entity\EntityWithPluginCollectionInterface;
use Drupal\Core\Entity\Plugin\DataType\ConfigEntityAdapter;
use Drupal\Core\Language\LanguageInterface;
use Drupal\Core\Language\LanguageManager;
use Drupal\Core\TypedData\Plugin\DataType\LanguageReference;
use Drupal\Core\TypedData\TypedDataInterface;
use Drupal\Core\Validation\Plugin\Validation\Constraint\FullyValidatableConstraint;
use Drupal\KernelTests\KernelTestBase;
use Drupal\language\Entity\ConfigurableLanguage;
// cspell:ignore kthxbai

/**
 * Base class for testing validation of config entities.
 *
 * @group config
 * @group Validation
 */
abstract class ConfigEntityValidationTestBase extends KernelTestBase {
    
    /**
     * {@inheritdoc}
     */
    protected static $modules = [
        'system',
    ];
    
    /**
     * The config entity being tested.
     *
     * @var \Drupal\Core\Config\Entity\ConfigEntityInterface
     */
    protected ConfigEntityInterface $entity;
    
    /**
     * Whether a config entity of this type has a label.
     *
     * Most config entity types ensure their entities have a label. But a few do
     * not, typically highly abstract/very low level config entities without a
     * strong UI presence. For example: REST resource configuration entities and
     * entity view displays.
     *
     * @var bool
     *
     * @see \Drupal\Core\Entity\EntityInterface::label()
     */
    protected bool $hasLabel = TRUE;
    
    /**
     * The config entity mapping properties with >=1 required keys.
     *
     * All top-level properties of a config entity are guaranteed to be defined
     * (since they are defined as properties on the corresponding PHP class). That
     * is why they can never trigger "required key" validation errors. Only for
     * non-top-level properties can such validation errors be triggered, and hence
     * that is only possible on top-level properties of `type: mapping`.
     *
     * @var string[]
     * @see \Drupal\Core\Config\Entity\ConfigEntityType::getPropertiesToExport()
     * @see ::testRequiredPropertyKeysMissing()
     * @see \Drupal\Core\Validation\Plugin\Validation\Constraint\ValidKeysConstraintValidator
     */
    protected static array $propertiesWithRequiredKeys = [];
    
    /**
     * The config entity properties whose values are optional (set to NULL).
     *
     * @var string[]
     * @see \Drupal\Core\Config\Entity\ConfigEntityTypeInterface::getPropertiesToExport()
     * @see ::testRequiredPropertyValuesMissing()
     */
    protected static array $propertiesWithOptionalValues = [
        '_core',
        'third_party_settings',
    ];
    
    /**
     * {@inheritdoc}
     */
    protected function setUp() : void {
        parent::setUp();
        $this->installConfig('system');
        // Install Stark so we can add a legitimately installed theme to config
        // dependencies.
        $this->container
            ->get('theme_installer')
            ->install([
            'stark',
        ]);
        $this->container = $this->container
            ->get('kernel')
            ->getContainer();
    }
    
    /**
     * Ensures that the entity created in ::setUp() has no validation errors.
     */
    public function testEntityIsValid() : void {
        $this->assertInstanceOf(ConfigEntityInterface::class, $this->entity);
        $this->assertValidationErrors([]);
    }
    
    /**
     * Returns the validation constraints applied to the entity's ID.
     *
     * If the entity type does not define an ID key, the test will fail. If an ID
     * key is defined but is not using the `machine_name` data type, the test will
     * be skipped.
     *
     * @return array[]
     *   The validation constraint configuration applied to the entity's ID.
     */
    protected function getMachineNameConstraints() : array {
        $id_key = $this->entity
            ->getEntityType()
            ->getKey('id');
        $this->assertNotEmpty($id_key, "The entity under test does not define an ID key.");
        $data_definition = $this->entity
            ->getTypedData()
            ->get($id_key)
            ->getDataDefinition();
        if ($data_definition->getDataType() === 'machine_name') {
            return $data_definition->getConstraints();
        }
        else {
            $this->markTestSkipped("The entity's ID key does not use the machine_name data type.");
        }
    }
    
    /**
     * Data provider for ::testInvalidMachineNameCharacters().
     *
     * @return array[]
     *   The test cases.
     */
    public static function providerInvalidMachineNameCharacters() : array {
        return [
            'INVALID: space separated' => [
                'space separated',
                FALSE,
            ],
            'INVALID: dash separated' => [
                'dash-separated',
                FALSE,
            ],
            'INVALID: uppercase letters' => [
                'Uppercase_Letters',
                FALSE,
            ],
            'INVALID: period separated' => [
                'period.separated',
                FALSE,
            ],
            'VALID: underscore separated' => [
                'underscore_separated',
                TRUE,
            ],
        ];
    }
    
    /**
     * Tests that the entity's ID is tested for invalid characters.
     *
     * @param string $machine_name
     *   A machine name to test.
     * @param bool $is_expected_to_be_valid
     *   Whether this machine name is expected to be considered valid.
     *
     * @dataProvider providerInvalidMachineNameCharacters
     */
    public function testInvalidMachineNameCharacters(string $machine_name, bool $is_expected_to_be_valid) : void {
        $constraints = $this->getMachineNameConstraints();
        $this->assertNotEmpty($constraints['Regex']);
        $this->assertIsArray($constraints['Regex']);
        $this->assertArrayHasKey('pattern', $constraints['Regex']);
        $this->assertIsString($constraints['Regex']['pattern']);
        $this->assertArrayHasKey('message', $constraints['Regex']);
        $this->assertIsString($constraints['Regex']['message']);
        $id_key = $this->entity
            ->getEntityType()
            ->getKey('id');
        if ($is_expected_to_be_valid) {
            $expected_errors = [];
        }
        else {
            $expected_errors = [
                $id_key => sprintf('The <em class="placeholder">&quot;%s&quot;</em> machine name is not valid.', $machine_name),
            ];
        }
        // Config entity IDs are immutable by default.
        $expected_errors[''] = "The '{$id_key}' property cannot be changed.";
        $this->entity
            ->set($id_key, $machine_name);
        $this->assertValidationErrors($expected_errors);
    }
    
    /**
     * Tests that the entity ID's length is validated if it is a machine name.
     */
    public function testMachineNameLength() : void {
        $constraints = $this->getMachineNameConstraints();
        $max_length = $constraints['Length']['max'];
        $this->assertIsInt($max_length);
        $this->assertGreaterThan(0, $max_length);
        $id_key = $this->entity
            ->getEntityType()
            ->getKey('id');
        $expected_errors = [
            $id_key => 'This value is too long. It should have <em class="placeholder">' . $max_length . '</em> characters or less.',
            // Config entity IDs are immutable by default.
'' => "The '{$id_key}' property cannot be changed.",
        ];
        $this->entity
            ->set($id_key, $this->randomMachineName($max_length + 2));
        $this->assertValidationErrors($expected_errors);
    }
    
    /**
     * Data provider for ::testConfigDependenciesValidation().
     *
     * @return array[]
     *   The test cases.
     */
    public static function providerConfigDependenciesValidation() : array {
        return [
            'valid dependency types' => [
                [
                    'config' => [
                        'system.site',
                    ],
                    'content' => [
                        'node:some-random-uuid',
                    ],
                    'module' => [
                        'system',
                    ],
                    'theme' => [
                        'stark',
                    ],
                ],
                [],
            ],
            'unknown dependency type' => [
                [
                    'fun_stuff' => [
                        'star-trek.deep-space-nine',
                    ],
                ],
                [
                    'dependencies.fun_stuff' => "'fun_stuff' is not a supported key.",
                ],
            ],
            'empty string in config dependencies' => [
                [
                    'config' => [
                        '',
                    ],
                ],
                [
                    'dependencies.config.0' => [
                        'This value should not be blank.',
                        "The '' config does not exist.",
                    ],
                ],
            ],
            'non-existent config dependency' => [
                [
                    'config' => [
                        'fake_settings',
                    ],
                ],
                [
                    'dependencies.config.0' => "The 'fake_settings' config does not exist.",
                ],
            ],
            'empty string in module dependencies' => [
                [
                    'module' => [
                        '',
                    ],
                ],
                [
                    'dependencies.module.0' => [
                        'This value should not be blank.',
                        "Module '' is not installed.",
                    ],
                ],
            ],
            'invalid module dependency' => [
                [
                    'module' => [
                        'invalid-module-name',
                    ],
                ],
                [
                    'dependencies.module.0' => [
                        'This value is not valid.',
                        "Module 'invalid-module-name' is not installed.",
                    ],
                ],
            ],
            'non-installed module dependency' => [
                [
                    'module' => [
                        'bad_judgment',
                    ],
                ],
                [
                    'dependencies.module.0' => "Module 'bad_judgment' is not installed.",
                ],
            ],
            'empty string in theme dependencies' => [
                [
                    'theme' => [
                        '',
                    ],
                ],
                [
                    'dependencies.theme.0' => [
                        'This value should not be blank.',
                        "Theme '' is not installed.",
                    ],
                ],
            ],
            'invalid theme dependency' => [
                [
                    'theme' => [
                        'invalid-theme-name',
                    ],
                ],
                [
                    'dependencies.theme.0' => [
                        'This value is not valid.',
                        "Theme 'invalid-theme-name' is not installed.",
                    ],
                ],
            ],
            'non-installed theme dependency' => [
                [
                    'theme' => [
                        'ugly_theme',
                    ],
                ],
                [
                    'dependencies.theme.0' => "Theme 'ugly_theme' is not installed.",
                ],
            ],
        ];
    }
    
    /**
     * Tests validation of config dependencies.
     *
     * @param array[] $dependencies
     *   The dependencies that should be added to the config entity under test.
     * @param array<string, string|string[]> $expected_messages
     *   The expected validation error messages. Keys are property paths, values
     *   are the expected messages: a string if a single message is expected, an
     *   array of strings if multiple are expected.
     *
     * @dataProvider providerConfigDependenciesValidation
     */
    public function testConfigDependenciesValidation(array $dependencies, array $expected_messages) : void {
        // Add the dependencies we were given to the dependencies that may already
        // exist in the entity.
        $dependencies = NestedArray::mergeDeep($dependencies, $this->entity
            ->getDependencies());
        $this->entity
            ->set('dependencies', $dependencies);
        $this->assertValidationErrors($expected_messages);
        // Enforce these dependencies, and ensure we get the same results.
        $this->entity
            ->set('dependencies', [
            'enforced' => $dependencies,
        ]);
        // We now expect validation errors not at `dependencies.module.0`, but at
        // `dependencies.enforced.module.0`. So reuse the same messages, but perform
        // string replacement in the keys.
        $expected_enforced_messages = array_combine(str_replace('dependencies', 'dependencies.enforced', array_keys($expected_messages)), array_values($expected_messages));
        $this->assertValidationErrors($expected_enforced_messages);
    }
    
    /**
     * 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 do not have a label.
        if (!$this->hasLabel) {
            $this->markTestSkipped();
        }
        if ($this->entity
            ->getEntityType()
            ->getKey('label') === $this->entity
            ->getEntityType()
            ->getKey('id')) {
            $this->markTestSkipped('This entity type uses the ID as the label; an entity without a label is hence impossible.');
        }
        static::setLabel($this->entity, "Multi\nLine");
        $this->assertValidationErrors([
            $this->entity
                ->getEntityType()
                ->getKey('label') => "Labels are not allowed to span multiple lines or contain control characters.",
        ]);
    }
    
    /**
     * Sets the label of the given config entity.
     *
     * @param \Drupal\Core\Config\Entity\ConfigEntityInterface $entity
     *   The config entity to modify.
     * @param string $label
     *   The label to set.
     *
     * @see ::testLabelValidation()
     */
    protected static function setLabel(ConfigEntityInterface $entity, string $label) : void {
        $label_property = $entity->getEntityType()
            ->getKey('label');
        if ($label_property === FALSE) {
            throw new \LogicException(sprintf('Override %s to allow testing a %s without a label.', __METHOD__, (string) $entity->getEntityType()
                ->getSingularLabel()));
        }
        $entity->set($label_property, $label);
    }
    
    /**
     * Asserts a set of validation errors is raised when the entity is validated.
     *
     * @param array<string, string|string[]> $expected_messages
     *   The expected validation error messages. Keys are property paths, values
     *   are the expected messages: a string if a single message is expected, an
     *   array of strings if multiple are expected.
     */
    protected function assertValidationErrors(array $expected_messages) : void {
        
        /** @var \Drupal\Core\TypedData\TypedDataManagerInterface $typed_data */
        $typed_data = $this->container
            ->get('typed_data_manager');
        $definition = $typed_data->createDataDefinition('entity:' . $this->entity
            ->getEntityTypeId());
        $violations = $typed_data->create($definition, $this->entity)
            ->validate();
        $actual_messages = [];
        foreach ($violations as $violation) {
            $property_path = $violation->getPropertyPath();
            if (!isset($actual_messages[$property_path])) {
                $actual_messages[$property_path] = (string) $violation->getMessage();
            }
            else {
                // Transform value from string to array.
                if (is_string($actual_messages[$property_path])) {
                    $actual_messages[$property_path] = (array) $actual_messages[$violation->getPropertyPath()];
                }
                // And append.
                $actual_messages[$property_path][] = (string) $violation->getMessage();
            }
        }
        ksort($expected_messages);
        ksort($actual_messages);
        $this->assertSame($expected_messages, $actual_messages);
    }
    
    /**
     * Tests that the config entity's langcode is validated.
     */
    public function testLangcode() : void {
        $this->entity
            ->set('langcode', NULL);
        $this->assertValidationErrors([
            'langcode' => 'This value should not be null.',
        ]);
        // A langcode from the standard list should always be acceptable.
        $standard_languages = LanguageManager::getStandardLanguageList();
        $this->assertNotEmpty($standard_languages);
        $this->entity
            ->set('langcode', key($standard_languages));
        $this->assertValidationErrors([]);
        // All special, internal langcodes should be acceptable.
        $system_langcodes = [
            LanguageInterface::LANGCODE_NOT_SPECIFIED,
            LanguageInterface::LANGCODE_NOT_APPLICABLE,
            LanguageInterface::LANGCODE_DEFAULT,
            LanguageInterface::LANGCODE_SITE_DEFAULT,
            LanguageInterface::LANGCODE_SYSTEM,
        ];
        foreach ($system_langcodes as $langcode) {
            $this->entity
                ->set('langcode', $langcode);
            $this->assertValidationErrors([]);
        }
        // An invalid langcode should be unacceptable, even if it "looks" right.
        $fake_langcode = 'definitely-not-a-language';
        $this->assertArrayNotHasKey($fake_langcode, LanguageReference::getAllValidLangcodes());
        $this->entity
            ->set('langcode', $fake_langcode);
        $this->assertValidationErrors([
            'langcode' => 'The value you selected is not a valid choice.',
        ]);
        // If a new configurable language is created with a non-standard langcode,
        // it should be acceptable.
        $this->enableModules([
            'language',
        ]);
        // The language doesn't exist yet, so it shouldn't be a valid choice.
        $this->entity
            ->set('langcode', 'kthxbai');
        $this->assertValidationErrors([
            'langcode' => 'The value you selected is not a valid choice.',
        ]);
        // Once we create the language, it should be a valid choice.
        ConfigurableLanguage::createFromLangcode('kthxbai')->save();
        $this->assertValidationErrors([]);
    }
    
    /**
     * Tests that immutable properties cannot be changed.
     *
     * @param mixed[] $valid_values
     *   (optional) The values to set for the immutable properties, keyed by name.
     *   This should be used if the immutable properties can only accept certain
     *   values, e.g. valid plugin IDs.
     */
    public function testImmutableProperties(array $valid_values = []) : void {
        $constraints = $this->entity
            ->getEntityType()
            ->getConstraints();
        $this->assertNotEmpty($constraints['ImmutableProperties'], 'All config entities should have at least one immutable ID property.');
        foreach ($constraints['ImmutableProperties'] as $property_name) {
            $original_value = $this->entity
                ->get($property_name);
            $this->entity
                ->set($property_name, $valid_values[$property_name] ?? $this->randomMachineName());
            $this->assertValidationErrors([
                '' => "The '{$property_name}' property cannot be changed.",
            ]);
            $this->entity
                ->set($property_name, $original_value);
        }
    }
    
    /**
     * A property that is required must have a value (i.e. not NULL).
     *
     * @param string[]|null $additional_expected_validation_errors_when_missing
     *   Some required config entity properties have additional validation
     *   constraints that cause additional messages to appear. Keys must be
     *   config entity properties, values must be arrays as expected by
     *   ::assertValidationErrors().
     *
     * @todo Remove this optional parameter in https://www.drupal.org/project/drupal/issues/2820364#comment-15333069
     *
     * @return void
     */
    public function testRequiredPropertyKeysMissing(?array $additional_expected_validation_errors_when_missing = NULL) : void {
        $config_entity_properties = array_keys($this->entity
            ->getEntityType()
            ->getPropertiesToExport());
        if (!empty(array_diff(array_keys($additional_expected_validation_errors_when_missing ?? []), $config_entity_properties))) {
            throw new \LogicException(sprintf('The test %s lists `%s` in $additional_expected_validation_errors_when_missing but it is not a property of the `%s` config entity type.', get_called_class(), implode(', ', array_diff(array_keys($additional_expected_validation_errors_when_missing), $config_entity_properties)), $this->entity
                ->getEntityTypeId()));
        }
        $mapping_properties = array_keys(array_filter(ConfigEntityAdapter::createFromEntity($this->entity)
            ->getProperties(FALSE), fn(TypedDataInterface $v) => $v instanceof Mapping));
        $required_property_keys = $this->getRequiredPropertyKeys();
        if (!$this->isFullyValidatable()) {
            $this->assertEmpty($required_property_keys, 'No keys can be required when a config entity type is not fully validatable.');
        }
        $original_entity = clone $this->entity;
        foreach ($mapping_properties as $property) {
            $this->entity = clone $original_entity;
            $this->entity
                ->set($property, []);
            $expected_validation_errors = array_key_exists($property, $required_property_keys) ? [
                $property => $required_property_keys[$property],
            ] : [];
            $this->assertValidationErrors(($additional_expected_validation_errors_when_missing[$property] ?? []) + $expected_validation_errors);
        }
    }
    
    /**
     * A property that is required must have a value (i.e. not NULL).
     *
     * @param string[]|null $additional_expected_validation_errors_when_missing
     *   Some required config entity properties have additional validation
     *   constraints that cause additional messages to appear. Keys must be
     *   config entity properties, values must be arrays as expected by
     *   ::assertValidationErrors().
     *
     * @todo Remove this optional parameter in https://www.drupal.org/project/drupal/issues/2820364#comment-15333069
     *
     * @return void
     */
    public function testRequiredPropertyValuesMissing(?array $additional_expected_validation_errors_when_missing = NULL) : void {
        $config_entity_properties = array_keys($this->entity
            ->getEntityType()
            ->getPropertiesToExport());
        // Guide developers when $additional_expected_validation_errors_when_missing
        // does not contain sensible values.
        $non_existing_properties = array_diff(array_keys($additional_expected_validation_errors_when_missing ?? []), $config_entity_properties);
        if ($non_existing_properties) {
            throw new \LogicException(sprintf('The test %s lists `%s` in $additional_expected_validation_errors_when_missing but it is not a property of the `%s` config entity type.', __METHOD__, implode(', ', $non_existing_properties), $this->entity
                ->getEntityTypeId()));
        }
        $properties_with_optional_values = $this->getPropertiesWithOptionalValues();
        // Get the config entity properties that are immutable.
        // @see ::testImmutableProperties()
        $immutable_properties = $this->entity
            ->getEntityType()
            ->getConstraints()['ImmutableProperties'];
        // Config entity properties containing plugin collections are special cases:
        // setting them to NULL would cause them to get out of sync with the plugin
        // collection.
        // @see \Drupal\Core\Config\Entity\ConfigEntityBase::set()
        // @see \Drupal\Core\Config\Entity\ConfigEntityBase::preSave()
        $plugin_collection_properties = $this->entity instanceof EntityWithPluginCollectionInterface ? array_keys($this->entity
            ->getPluginCollections()) : [];
        // To test properties with missing required values, $this->entity must be
        // modified to be able to use ::assertValidationErrors(). To allow restoring
        // $this->entity to its original value for each tested property, a clone of
        // the original entity is needed.
        $original_entity = clone $this->entity;
        foreach ($config_entity_properties as $property) {
            // Do not try to set immutable properties to NULL: their immutability is
            // already tested.
            // @see ::testImmutableProperties()
            if (in_array($property, $immutable_properties, TRUE)) {
                continue;
            }
            // Do not try to set plugin collection properties to NULL.
            if (in_array($property, $plugin_collection_properties, TRUE)) {
                continue;
            }
            $this->entity = clone $original_entity;
            $this->entity
                ->set($property, NULL);
            $expected_validation_errors = in_array($property, $properties_with_optional_values, TRUE) ? [] : [
                $property => 'This value should not be null.',
            ];
            // @see `type: required_label`
            // @see \Symfony\Component\Validator\Constraints\NotBlank
            if (!$this->isFullyValidatable() && $this->entity
                ->getEntityType()
                ->getKey('label') == $property) {
                $expected_validation_errors = [
                    $property => 'This value should not be blank.',
                ];
            }
            $this->assertValidationErrors(($additional_expected_validation_errors_when_missing[$property] ?? []) + $expected_validation_errors);
        }
    }
    
    /**
     * Whether the tested config entity type is fully validatable.
     *
     * @return bool
     *   Whether the tested config entity type is fully validatable.
     */
    protected function isFullyValidatable() : bool {
        $typed_config = $this->container
            ->get('config.typed');
        assert($typed_config instanceof TypedConfigManagerInterface);
        // @see \Drupal\Core\Entity\Plugin\DataType\ConfigEntityAdapter::getConfigTypedData()
        $config_entity_type_schema_constraints = $typed_config->createFromNameAndData($this->entity
            ->getConfigDependencyName(), $this->entity
            ->toArray())
            ->getConstraints();
        foreach ($config_entity_type_schema_constraints as $constraint) {
            if ($constraint instanceof FullyValidatableConstraint) {
                return TRUE;
            }
        }
        return FALSE;
    }
    
    /**
     * Determines the config entity mapping properties with required keys.
     *
     * This refers only to the top-level properties of the config entity which are expected to be mappings, and of those mappings, only the ones which have required keys.
     *
     * @return string[]
     *   An array of key-value pairs, with:
     *   - keys: names of the config entity properties which are mappings that
     *     contain required keys.
     *   - values: the corresponding expected validation error message.
     */
    protected function getRequiredPropertyKeys() : array {
        // If a config entity type is not fully validatable, no mapping property
        // keys are required.
        if (!$this->isFullyValidatable()) {
            return [];
        }
        $config_entity_properties = array_keys($this->entity
            ->getEntityType()
            ->getPropertiesToExport());
        // Otherwise, all mapping property keys are required except for those marked
        // optional. Rather than inspecting config schema, require authors of tests
        // to explicitly list optional properties in a `propertiesWithRequiredKeys`
        // property on this class.
        // @see \Drupal\KernelTests\Config\Schema\MappingTest::testMappingInterpretation()
        $class = static::class;
        $properties_with_required_keys = [];
        while ($class) {
            if (property_exists($class, 'propertiesWithRequiredKeys')) {
                $properties_with_required_keys += $class::$propertiesWithRequiredKeys;
            }
            $class = get_parent_class($class);
        }
        // Guide developers when $propertiesWithRequiredKeys does not contain
        // sensible values.
        if (!empty(array_diff(array_keys($properties_with_required_keys), $config_entity_properties))) {
            throw new \LogicException(sprintf('The %s test class lists %s in $propertiesWithRequiredKeys but it is not a property of the %s config entity type.', get_called_class(), implode(', ', array_diff(array_keys($properties_with_required_keys), $config_entity_properties)), $this->entity
                ->getEntityTypeId()));
        }
        return $properties_with_required_keys;
    }
    
    /**
     * Determines the config entity properties with optional values.
     *
     * @return string[]
     *   The config entity properties whose values are optional.
     */
    protected function getPropertiesWithOptionalValues() : array {
        $config_entity_properties = array_keys($this->entity
            ->getEntityType()
            ->getPropertiesToExport());
        // If a config entity type is not fully validatable, all properties are
        // optional, with the exception of `type: langcode` and
        // `type: required_label`.
        if (!$this->isFullyValidatable()) {
            return array_diff($config_entity_properties, [
                // @see `type: langcode`
                // @see \Symfony\Component\Validator\Constraints\NotNull
'langcode',
                'default_langcode',
                // @see `type: required_label`
                // @see \Symfony\Component\Validator\Constraints\NotBlank
$this->entity
                    ->getEntityType()
                    ->getKey('label'),
            ]);
        }
        // Otherwise, all properties are required except for those marked
        // optional. Rather than inspecting config schema, require authors of tests
        // to explicitly list optional properties in a
        // `propertiesWithOptionalValues` property on this class.
        $class = static::class;
        $optional_properties = [];
        while ($class) {
            if (property_exists($class, 'propertiesWithOptionalValues')) {
                $optional_properties = array_merge($optional_properties, $class::$propertiesWithOptionalValues);
            }
            $class = get_parent_class($class);
        }
        $optional_properties = array_unique($optional_properties);
        // Guide developers when $optionalProperties does not contain sensible
        // values.
        $non_existing_properties = array_diff($optional_properties, $config_entity_properties);
        if ($non_existing_properties) {
            throw new \LogicException(sprintf('The %s test class lists %s in $optionalProperties but it is not a property of the %s config entity type.', static::class, implode(', ', $non_existing_properties), $this->entity
                ->getEntityTypeId()));
        }
        return $optional_properties;
    }

}