diff --git a/src/Plugin/search_api/processor/SearchApiExcludeEntityProcessor.php b/src/Plugin/search_api/processor/SearchApiExcludeEntityProcessor.php
index 51a8cbc..db8fd30 100644
--- a/src/Plugin/search_api/processor/SearchApiExcludeEntityProcessor.php
+++ b/src/Plugin/search_api/processor/SearchApiExcludeEntityProcessor.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\search_api_exclude_entity\Plugin\search_api\processor;
 
+use Drupal\Core\Entity\EntityFieldManagerInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\PluginFormInterface;
 use Drupal\search_api\Plugin\PluginFormTrait;
@@ -24,7 +25,12 @@ class SearchApiExcludeEntityProcessor extends ProcessorPluginBase implements Plu
 
   use PluginFormTrait;
 
-  protected $entity_manager;
+  /**
+   * The entity field manager.
+   *
+   * @var \Drupal\Core\Entity\EntityFieldManagerInterface|null
+   */
+  protected $entityFieldManager;
 
   /**
    * {@inheritdoc}
@@ -32,11 +38,36 @@ class SearchApiExcludeEntityProcessor extends ProcessorPluginBase implements Plu
   public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
     /** @var static $processor */
     $processor = parent::create($container, $configuration, $plugin_id, $plugin_definition);
-    $processor->entity_manager = $container->get('entity.manager');
+
+    $processor->setEntityFieldManager($container->get('entity_field.manager'));
+
     return $processor;
   }
 
   /**
+   * Retrieves the entity field manager.
+   *
+   * @return \Drupal\Core\Entity\EntityFieldManagerInterface
+   *   The entity field manager.
+   */
+  public function getEntityFieldManager() {
+    return $this->entityFieldManager ?: \Drupal::service('entity_field.manager');
+  }
+
+  /**
+   * Sets the entity field manager.
+   *
+   * @param \Drupal\Core\Entity\EntityFieldManagerInterface $entity_field_manager
+   *   The new entity field manager.
+   *
+   * @return $this
+   */
+  public function setEntityFieldManager(EntityFieldManagerInterface $entity_field_manager) {
+    $this->entityFieldManager = $entity_field_manager;
+    return $this;
+  }
+
+  /**
    * {@inheritdoc}
    */
   public function defaultConfiguration() {
@@ -97,7 +128,7 @@ class SearchApiExcludeEntityProcessor extends ProcessorPluginBase implements Plu
    *   Options array with bundles.
    */
   private function getFieldOptions($entity_type, $datasource) {
-    $field_map = $this->entity_manager->getFieldMapByFieldType('search_api_exclude_entity');
+    $field_map = $this->getEntityFieldManager()->getFieldMapByFieldType('search_api_exclude_entity');
     $bundles = $datasource->getBundles();
 
     $options = array();
@@ -132,14 +163,14 @@ class SearchApiExcludeEntityProcessor extends ProcessorPluginBase implements Plu
    * @param string $field
    *   The field we are checking if it is being used by the bundle.
    *
-   * @return array
-   *   Options array with bundles.
+   * @return bool
+   *   TRUE if the entity bundle has the field, FALSE otherwise.
    */
   private function bundleHasField($entity_type, $bundle, $field) {
     static $field_map;
 
     if (!isset($field_map)) {
-      $field_map = $this->entity_manager->getFieldMapByFieldType('search_api_exclude_entity');
+      $field_map = $this->getEntityFieldManager()->getFieldMapByFieldType('search_api_exclude_entity');
     }
 
     return isset($field_map[$entity_type][$field]['bundles'][$bundle]);
diff --git a/tests/src/Unit/Processor/SearchApiExcludeEntityProcessorTest.php b/tests/src/Unit/Processor/SearchApiExcludeEntityProcessorTest.php
new file mode 100644
index 0000000..084fc65
--- /dev/null
+++ b/tests/src/Unit/Processor/SearchApiExcludeEntityProcessorTest.php
@@ -0,0 +1,198 @@
+<?php
+
+namespace Drupal\Tests\search_api_exclude_entity\Unit\Processor;
+
+use Drupal\Core\Entity\EntityFieldManagerInterface;
+use Drupal\Core\Entity\Plugin\DataType\EntityAdapter;
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\node\NodeInterface;
+use Drupal\search_api\IndexInterface;
+use Drupal\search_api\Utility\Utility;
+use Drupal\search_api_exclude_entity\Plugin\search_api\processor\SearchApiExcludeEntityProcessor;
+use Drupal\Tests\search_api\Unit\Processor\TestItemsTrait;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Tests the "Search API Exclude Entity" processor.
+
+ * @coversDefaultClass \Drupal\search_api_exclude_entity\Plugin\search_api\processor\SearchApiExcludeEntityProcessor
+ * @group search_api_exclude_entity
+ *
+ * @see \Drupal\search_api_exclude_entity\Plugin\search_api\processor\SearchApiExcludeEntityProcessor
+ */
+class SearchApiExcludeEntityProcessorTest extends UnitTestCase {
+
+  use TestItemsTrait;
+
+  /**
+   * The processor to be tested.
+   *
+   * @var \Drupal\search_api_exclude_entity\Plugin\search_api\processor\SearchApiExcludeEntityProcessor
+   */
+  protected $processor;
+
+  /**
+   * The fields helper service.
+   *
+   * @var \Drupal\search_api\Utility\FieldsHelperInterface
+   */
+  protected $fieldsHelper;
+
+  /**
+   * The test index.
+   *
+   * @var \Drupal\search_api\IndexInterface
+   */
+  protected $index;
+
+  /**
+   * The field name of the first exclude field.
+   *
+   * @var string
+   */
+  protected $fieldName1 = 'field_exclude_1';
+
+  /**
+   * The field name of the second exclude field.
+   *
+   * @var string
+   */
+  protected $fieldName2 = 'field_exclude_2';
+
+  /**
+   * The value of an enabled (checked) exclude field.
+   *
+   * @var \Drupal\Core\Field\FieldItemListInterface
+   */
+  protected $excludeEnabledValue;
+
+  /**
+   * The value of a disabled (unchecked) exclude field.
+   *
+   * @var \Drupal\Core\Field\FieldItemListInterface
+   */
+  protected $excludeDisabledValue;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $this->setUpMockContainer();
+
+    $this->fieldsHelper = \Drupal::getContainer()->get('search_api.fields_helper');
+    $this->index = $this->createMock(IndexInterface::class);
+
+    $this->excludeEnabledValue = $this->createMock(FieldItemListInterface::class);
+    $this->excludeEnabledValue->method('getValue')
+      ->willReturn([0 => ['value' => '1']]);
+    $this->excludeDisabledValue = $this->createMock(FieldItemListInterface::class);
+    $this->excludeDisabledValue->method('getValue')
+      ->willReturn([0 => ['value' => '0']]);
+
+    // Node type 'article' has two exclude fields.
+    $entity_field_manager = $this->createMock(EntityFieldManagerInterface::class);
+    $entity_field_manager->method('getFieldMapByFieldType')
+      ->with('search_api_exclude_entity')
+      ->willReturn([
+        'node' => [
+          $this->fieldName1 => [
+            'type' => 'search_api_exclude_entity',
+            'bundles' => ['article' => 'article'],
+          ],
+          $this->fieldName2 => [
+            'type' => 'search_api_exclude_entity',
+            'bundles' => ['article' => 'article'],
+          ],
+        ],
+      ]);
+
+    $configuration['fields']['node'] = [
+      $this->fieldName1,
+      $this->fieldName2
+    ];
+
+    /** @var \Drupal\Core\Entity\EntityFieldManagerInterface $entity_field_manager */
+    $this->processor = new SearchApiExcludeEntityProcessor($configuration, 'search_api_exclude_entity_processor', []);
+    $this->processor->setEntityFieldManager($entity_field_manager);
+  }
+
+  /**
+   * Helper function for creating node based mock search index items.
+   *
+   * @param string $bundle
+   *   The bundle name of the mock node.
+   * @param string $raw_id
+   *   The raw ID of the mock search index item.
+   * @param \Drupal\Core\Field\FieldItemListInterface $field_value_1
+   *   (Optional) The value of the first exclude field of the mock node.
+   * @param \Drupal\Core\Field\FieldItemListInterface $field_value_2
+   *   (Optional) The value of the second exclude field of the mock node.
+   *
+   * @return \Drupal\search_api\Item\ItemInterface
+   */
+  protected function createMockItem($bundle, $raw_id, $field_value_1 = NULL, $field_value_2 = NULL) {
+    $node = $this->createMock(NodeInterface::class);
+    $node->method('getEntityTypeId')->willReturn('node');
+    $node->method('bundle')->willReturn($bundle);
+
+    $node->method('get')
+      ->will($this->returnValueMap([
+        [$this->fieldName1, $field_value_1],
+        [$this->fieldName2, $field_value_2],
+      ]));
+
+    /** @var \Drupal\search_api\Item\ItemInterface $item */
+    /** @var \Drupal\node\NodeInterface $node */
+    $id = Utility::createCombinedId('entity:node', $raw_id);
+    $item = $this->fieldsHelper->createItem($this->index, $id);
+    $item->setOriginalObject(EntityAdapter::createFromEntity($node));
+
+    return $item;
+  }
+
+  /**
+   * Tests altering the indexed items.
+   *
+   * @covers ::alterIndexedItems
+   */
+  public function testAlterIndexedItems() {
+    $item1 = $this->createMockItem(
+      'page',
+      '1:en'
+    );
+    $item2 = $this->createMockItem(
+      'article',
+      '2:en',
+      $this->excludeDisabledValue,
+      $this->excludeDisabledValue
+    );
+    $item3 = $this->createMockItem(
+      'article',
+      '3:en',
+      $this->excludeDisabledValue,
+      $this->excludeEnabledValue
+    );
+    $item4 = $this->createMockItem(
+      'article',
+      '4:en',
+      $this->excludeEnabledValue,
+      $this->excludeEnabledValue
+    );
+
+    $items = [
+      $item1->getId() => $item1,
+      $item2->getId() => $item2,
+      $item3->getId() => $item3,
+      $item4->getId() => $item4,
+    ];
+
+    $this->processor->alterIndexedItems($items);
+
+    $this->assertTrue(!empty($items[$item1->getId()]), "Item without any exclude fields wasn't removed.");
+    $this->assertTrue(!empty($items[$item2->getId()]), "Item with 0/2 of exclude fields enabled wasn't removed.");
+    $this->assertTrue(empty($items[$item3->getId()]), "Item with 1/2 of exclude fields enabled was removed.");
+    $this->assertTrue(empty($items[$item4->getId()]), "Item with 2/2 of exclude fields enabled was removed.");
+  }
+}