diff --git a/config/schema/search_api_solr.backend.schema.yml b/config/schema/search_api_solr.backend.schema.yml
index 68d4978..a9b2481 100644
--- a/config/schema/search_api_solr.backend.schema.yml
+++ b/config/schema/search_api_solr.backend.schema.yml
@@ -67,6 +67,9 @@ search_api.backend.plugin.search_api_solr:
         http_method:
           type: string
           label: 'Use Get or Post for the Solr Queries'
+        site_hash:
+          type: string
+          label: 'Site hash'
     solr_version:
       type: string
       label: 'Solr version override'
diff --git a/src/Plugin/search_api/backend/SearchApiSolrBackend.php b/src/Plugin/search_api/backend/SearchApiSolrBackend.php
index 2d732e1..229d207 100644
--- a/src/Plugin/search_api/backend/SearchApiSolrBackend.php
+++ b/src/Plugin/search_api/backend/SearchApiSolrBackend.php
@@ -1175,12 +1175,11 @@ class SearchApiSolrBackend extends BackendPluginBase {
    *   An array describing facets that apply to the current results.
    */
   protected function extractFacets(QueryInterface $query, Result $resultset) {
-    $facets = array();
-
     if (!$resultset->getFacetSet()) {
-      return $facets;
+      return array();
     }
 
+    $facets = array();
     $index = $query->getIndex();
     $field_names = $this->getFieldNames($index);
     $fields = $index->getFields();
@@ -1356,9 +1355,11 @@ class SearchApiSolrBackend extends BackendPluginBase {
    */
   protected function setFacets(array $facets, array $field_names, Query $solarium_query) {
     $fq = array();
-    if (!$facets) {
+
+    if (empty($facets)) {
       return;
     }
+
     $facet_set = $solarium_query->getFacetSet();
     $facet_set->setSort('count');
     $facet_set->setLimit(10);
@@ -1373,7 +1374,7 @@ class SearchApiSolrBackend extends BackendPluginBase {
       // String fields have their own corresponding facet fields.
       $field = $field_names[$info['field']];
       // Check for the "or" operator.
-      if (isset($info['operator']) && $info['operator'] === 'or') {
+      if (isset($info['operator']) && strtolower($info['operator']) === 'or') {
         // Remember that filters for this field should be tagged.
         $escaped = SearchApiSolrUtility::escapeFieldName($field_names[$info['field']]);
         $taggedFields[$escaped] = "{!tag=$escaped}";
@@ -1393,11 +1394,16 @@ class SearchApiSolrBackend extends BackendPluginBase {
       if ($info['min_count'] != 1) {
         $facet_field->setMinCount($info['min_count']);
       }
+
       // Set missing, if specified.
       if ($info['missing']) {
         $facet_field->setMissing(TRUE);
       }
+      else {
+        $facet_field->setMissing(FALSE);
+      }
     }
+
     // Tag filters of fields with "OR" facets.
     foreach ($taggedFields as $field => $tag) {
       $regex = '#(?<![^( ])' . preg_quote($field, '#') . ':#';
diff --git a/src/Tests/IntegrationTest.php b/src/Tests/IntegrationTest.php
new file mode 100644
index 0000000..48c51e4
--- /dev/null
+++ b/src/Tests/IntegrationTest.php
@@ -0,0 +1,428 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\search_api_solr\Tests\IntegrationTest.
+ */
+
+namespace Drupal\search_api_solr\Tests;
+
+use Drupal\Component\Utility\Html;
+use Drupal\search_api\Entity\Index;
+use Drupal\search_api\Entity\Server;
+use Drupal\search_api\SearchApiException;
+use Drupal\search_api\Tests\WebTestBase;
+use Drupal\search_api\Utility;
+
+/**
+ * Tests the overall functionality of the Search API framework and admin UI.
+ *
+ * @group search_api
+ */
+class IntegrationTest extends WebTestBase {
+
+  /**
+   * The ID of the search server used for this test.
+   *
+   * @var string
+   */
+  protected $serverId;
+
+  /**
+   * A storage instance for indexes.
+   *
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  protected $indexStorage;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = array(
+    'node',
+    'search_api',
+    'search_api_solr',
+    'field_ui',
+  );
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+    $this->indexStorage = \Drupal::entityTypeManager()->getStorage('search_api_index');
+
+    $this->drupalLogin($this->adminUser);
+  }
+
+  /**
+   * Tests various operations via the Search API's admin UI.
+   */
+  public function testFramework() {
+    $filepath = drupal_get_path('module', 'search_api_solr') . '/vendor/autoload.php';
+    if (!class_exists('Solarium\\Client') && ($filepath != DRUPAL_ROOT . '/core/vendor/autoload.php')) {
+      require $filepath;
+    }
+
+    // Login as an admin user for the rest of the tests.
+    $this->drupalLogin($this->adminUser);
+
+    $this->createServer();
+    $this->createIndex();
+    $this->checkContentEntityTracking();
+    $this->changeIndexServer();
+  }
+
+  /**
+   * Tests creating a search server via the UI.
+   */
+  protected function createServer($server_id = '_test_server') {
+    $this->serverId = $server_id;
+    $server_name = 'Search API &{}<>! Server';
+    $server_description = 'A >server< used for testing &.';
+    $edit_path = 'admin/config/search/search-api/add-server';
+
+    $this->drupalGet($edit_path);
+    $this->assertResponse(200, 'Server add page exists');
+
+    $edit = array(
+      'name' => '',
+      'status' => 1,
+      'description' => 'A server used for testing.',
+      'backend' => 'search_api_solr',
+    );
+
+    $this->drupalPostForm($edit_path, $edit, $this->t('Save'));
+    $this->assertText($this->t('@name field is required.', array('@name' => $this->t('Server name'))));
+
+    $edit = array(
+      'name' => $server_name,
+      'status' => 1,
+      'description' => $server_description,
+      'backend' => 'search_api_solr',
+    );
+    $this->drupalPostForm($edit_path, $edit, $this->t('Save'));
+    $this->assertText($this->t('@name field is required.', array('@name' => $this->t('Machine-readable name'))));
+
+    $edit = array(
+      'name' => $server_name,
+      'id' => $this->serverId,
+      'status' => 1,
+      'description' => $server_description,
+      'backend' => 'search_api_solr',
+    );
+
+    $this->drupalPostForm(NULL, $edit, $this->t('Save'));
+
+    $this->assertText($this->t('The server was successfully saved.'));
+    $this->assertUrl('admin/config/search/search-api/server/' . $this->serverId, array(), 'Correct redirect to server page.');
+    $this->assertHtmlEscaped($server_name);
+    $this->assertHtmlEscaped($server_description);
+
+    // Go back in and configure solr.
+    $edit_path = 'admin/config/search/search-api/server/' . $this->serverId . '/edit';
+    $this->drupalGet($edit_path);
+    $edit = [
+      'backend_config[host]' => 'localhost',
+      'backend_config[port]' =>'8983',
+      'backend_config[path]' =>'/solr/d8',
+    ];
+    $this->drupalPostForm(NULL, $edit, $this->t('Save'));
+
+    $this->drupalGet('admin/config/search/search-api');
+    $this->assertHtmlEscaped($server_name);
+    $this->assertHtmlEscaped($server_description);
+  }
+
+  /**
+   * Tests creating a search index via the UI.
+   */
+  protected function createIndex() {
+    $settings_path = 'admin/config/search/search-api/add-index';
+    $this->indexId = 'test_index';
+    $index_description = 'An >index< used for &! tęsting.';
+    $index_name = 'Search >API< test &!^* index';
+
+    $this->drupalGet($settings_path);
+    $this->assertResponse(200);
+    $edit = array(
+      'status' => 1,
+      'description' => $index_description,
+    );
+
+    $this->drupalPostForm(NULL, $edit, $this->t('Save'));
+    $this->assertText($this->t('@name field is required.', array('@name' => $this->t('Index name'))));
+    $this->assertText($this->t('@name field is required.', array('@name' => $this->t('Machine-readable name'))));
+    $this->assertText($this->t('@name field is required.', array('@name' => $this->t('Data sources'))));
+
+
+    $edit = array(
+      'name' => $index_name,
+      'id' => $this->indexId,
+      'status' => 1,
+      'description' => $index_description,
+      'server' => $this->serverId,
+      'datasources[]' => array('entity:node'),
+    );
+
+    $this->drupalPostForm(NULL, $edit, $this->t('Save'));
+
+    $this->assertText($this->t('The index was successfully saved.'));
+    // @todo Make this work correctly.
+    // $this->assertUrl($this->getIndexPath('fields/add'), array(), 'Correct redirect to index page.');
+    $this->assertHtmlEscaped($index_name);
+
+    $this->drupalGet($this->getIndexPath('edit'));
+    $this->assertHtmlEscaped($index_name);
+
+    $this->indexStorage->resetCache(array($this->indexId));
+    /** @var $index \Drupal\search_api\IndexInterface */
+    $index = $this->indexStorage->load($this->indexId);
+
+    if ($this->assertTrue($index, 'Index was correctly created.')) {
+      $this->assertEqual($index->label(), $edit['name'], 'Name correctly inserted.');
+      $this->assertEqual($index->id(), $edit['id'], 'Index ID correctly inserted.');
+      $this->assertTrue($index->status(), 'Index status correctly inserted.');
+      $this->assertEqual($index->getDescription(), $edit['description'], 'Index ID correctly inserted.');
+      $this->assertEqual($index->getServerId(), $edit['server'], 'Index server ID correctly inserted.');
+      $this->assertEqual($index->getDatasourceIds(), $edit['datasources[]'], 'Index datasource id correctly inserted.');
+    }
+    else {
+      // Since none of the other tests would work, bail at this point.
+      throw new SearchApiException();
+    }
+
+    // Test the "Save and edit" button.
+    $index2_id = 'test_index2';
+    $edit['id'] = $index2_id;
+    unset($edit['server']);
+    $this->drupalPostForm($settings_path, $edit, $this->t('Save and edit'));
+
+    $this->assertText($this->t('The index was successfully saved.'));
+    $this->indexStorage->resetCache(array($index2_id));
+    $index = $this->indexStorage->load($index2_id);
+    $this->assertUrl($index->toUrl('add-fields'), array(), 'Correct redirect to index fields page.');
+
+    $this->drupalGet('admin/config/search/search-api');
+    $this->assertHtmlEscaped($index_name);
+    $this->assertHtmlEscaped($index_description);
+  }
+
+  /**
+   * Tests whether the tracking information is properly maintained.
+   *
+   * Will especially test the bundle option of the content entity datasource.
+   */
+  protected function checkContentEntityTracking() {
+    // Initially there should be no tracked items, because there are no nodes.
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 0, 'No items are tracked yet.');
+
+    // Add two articles and a page.
+    $article1 = $this->drupalCreateNode(array('type' => 'article'));
+    $this->drupalCreateNode(array('type' => 'article'));
+    $this->drupalCreateNode(array('type' => 'page'));
+
+    // Those 3 new nodes should be added to the tracking table immediately.
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 3, 'Three items are tracked.');
+
+    $node_count = \Drupal::entityQuery('node')->count()->execute();
+    $this->assertEqual($node_count, $tracked_items);
+
+    // Test disabling the index.
+    $settings_path = $this->getIndexPath('edit');
+    $this->drupalGet($settings_path);
+    $edit = array(
+      'status' => FALSE,
+      'datasource_configs[entity:node][default]' => 0,
+      'datasource_configs[entity:node][bundles][article]' => FALSE,
+      'datasource_configs[entity:node][bundles][page]' => FALSE,
+    );
+    $this->drupalPostForm(NULL, $edit, $this->t('Save'));
+
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 0, 'No items are tracked.');
+
+    // Test re-enabling the index.
+    $this->drupalGet($settings_path);
+
+    $edit = array(
+      'status' => TRUE,
+      'datasource_configs[entity:node][default]' => 0,
+      'datasource_configs[entity:node][bundles][article]' => TRUE,
+      'datasource_configs[entity:node][bundles][page]' => TRUE,
+    );
+    $this->drupalPostForm(NULL, $edit, $this->t('Save'));
+
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 3, 'Three items are tracked.');
+
+    // Uncheck "default" and don't select any bundles. This should remove all
+    // items from the tracking table.
+    $edit = array(
+      'status' => TRUE,
+      'datasource_configs[entity:node][default]' => 0,
+      'datasource_configs[entity:node][bundles][article]' => FALSE,
+      'datasource_configs[entity:node][bundles][page]' => FALSE,
+    );
+    $this->drupalPostForm($settings_path, $edit, $this->t('Save'));
+
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 0, 'No items are tracked.');
+
+    // Leave "default" unchecked and select the "article" bundle. This should
+    // re-add the two articles to the tracking table.
+    $edit = array(
+      'status' => TRUE,
+      'datasource_configs[entity:node][default]' => 0,
+      'datasource_configs[entity:node][bundles][article]' => TRUE,
+      'datasource_configs[entity:node][bundles][page]' => FALSE,
+    );
+    $this->drupalPostForm($settings_path, $edit, $this->t('Save'));
+
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 2, 'Two items are tracked.');
+
+    // Leave "default" unchecked and select only the "page" bundle. This should
+    // result in only the page being present in the tracking table.
+    $edit = array(
+      'status' => TRUE,
+      'datasource_configs[entity:node][default]' => 0,
+      'datasource_configs[entity:node][bundles][article]' => FALSE,
+      'datasource_configs[entity:node][bundles][page]' => TRUE,
+    );
+    $this->drupalPostForm($settings_path, $edit, $this->t('Save'));
+
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 1, 'One item is tracked.');
+
+    // Check "default" again and select the "article" bundle. This shouldn't
+    // change the tracking table, which should still only contain the page.
+    $edit = array(
+      'status' => TRUE,
+      'datasource_configs[entity:node][default]' => 1,
+      'datasource_configs[entity:node][bundles][article]' => TRUE,
+      'datasource_configs[entity:node][bundles][page]' => FALSE,
+    );
+    $this->drupalPostForm($settings_path, $edit, $this->t('Save'));
+
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 1, 'One item is tracked.');
+
+    // Leave "default" checked but now select only the "page" bundle. This
+    // should result in only the articles being tracked.
+    $edit = array(
+      'status' => TRUE,
+      'datasource_configs[entity:node][default]' => 1,
+      'datasource_configs[entity:node][bundles][article]' => FALSE,
+      'datasource_configs[entity:node][bundles][page]' => TRUE,
+    );
+    $this->drupalPostForm($settings_path, $edit, $this->t('Save'));
+
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 2, 'Two items are tracked.');
+
+    // Delete an article. That should remove it from the item table.
+    $article1->delete();
+
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 1, 'One item is tracked.');
+
+    // Go back to the default setting to continue the test.
+    $edit = array(
+      'status' => TRUE,
+      'datasource_configs[entity:node][default]' => 1,
+      'datasource_configs[entity:node][bundles][article]' => FALSE,
+      'datasource_configs[entity:node][bundles][page]' => FALSE,
+    );
+    $this->drupalPostForm($settings_path, $edit, $this->t('Save'));
+
+    $tracked_items = $this->countTrackedItems();
+    $this->assertEqual($tracked_items, 2, 'Two items are tracked.');
+    $node_count = \Drupal::entityQuery('node')->count()->execute();
+    $this->assertEqual($node_count, $tracked_items, 'All nodes are correctly tracked by the index.');
+  }
+
+  /**
+   * Counts the number of tracked items in the test index.
+   *
+   * @return int
+   *   The number of tracked items in the test index.
+   */
+  protected function countTrackedItems() {
+    return $this->getIndex()->getTrackerInstance()->getTotalItemsCount();
+  }
+
+  /**
+   * Counts the number of unindexed items in the test index.
+   *
+   * @return int
+   *   The number of unindexed items in the test index.
+   */
+  protected function countRemainingItems() {
+    return $this->getIndex()->getTrackerInstance()->getRemainingItemsCount();
+  }
+
+  /**
+   * Changes the index's server and checks if it reacts correctly.
+   *
+   * The expected behavior is that, when an index's server is changed, all of
+   * the index's items should be removed from the previous server and marked as
+   * "unindexed" in the tracker.
+   */
+  protected function changeIndexServer() {
+    $this->indexStorage->resetCache(array($this->indexId));
+    /** @var $index \Drupal\search_api\IndexInterface */
+    $index = $this->indexStorage->load($this->indexId);
+
+    $node_count = \Drupal::entityQuery('node')->count()->execute();
+    $this->assertEqual($node_count, $this->countTrackedItems(), 'All nodes are correctly tracked by the index.');
+
+    // Index all remaining items on the index.
+    $index->indexItems();
+
+    $remaining_items = $this->countRemainingItems();
+    $this->assertEqual($remaining_items, 0, 'All items have been successfully indexed.');
+
+    // Create a second search server.
+    $this->createServer('test_server_2');
+
+    // Change the index's server to the new one.
+    $settings_path = $this->getIndexPath('edit');
+    $edit = array(
+      'server' => $this->serverId,
+    );
+    $this->drupalPostForm($settings_path, $edit, $this->t('Save'));
+
+    // After saving the new index, we should have called reindex.
+    $remaining_items = $this->countRemainingItems();
+    $this->assertEqual($remaining_items, $node_count, 'All items still need to be indexed.');
+  }
+
+  /**
+   * Retrieves test index.
+   *
+   * @return \Drupal\search_api\IndexInterface
+   *   The test index.
+   */
+  protected function getIndex() {
+    return Index::load($this->indexId);
+  }
+
+  /**
+   * Ensures that all occurrences of the string are properly escaped.
+   *
+   * This makes sure that the string is only mentioned in an escaped version and
+   * is never double escaped.
+   *
+   * @param string $string
+   *   The raw string to check for.
+   */
+  protected function assertHtmlEscaped($string) {
+    $this->assertRaw(Html::escape($string));
+    $this->assertNoRaw(Html::escape(Html::escape($string)));
+    $this->assertNoRaw($string);
+  }
+
+}
diff --git a/tests/modules/search_api_test_solr/config/install/search_api.index.solr_search_index.yml b/tests/modules/search_api_test_solr/config/install/search_api.index.solr_search_index.yml
index d7db38d..0472612 100644
--- a/tests/modules/search_api_test_solr/config/install/search_api.index.solr_search_index.yml
+++ b/tests/modules/search_api_test_solr/config/install/search_api.index.solr_search_index.yml
@@ -2,7 +2,7 @@ id: solr_search_index
 name: 'Test index'
 description: 'An index used for testing'
 read_only: false
-fields:
+field_settings:
   id:
     label: ID
     type: integer
@@ -40,25 +40,28 @@ fields:
     property_path: search_api_language
     index_locked: true
     type_locked: true
-processors:
+processor_settings:
   add_url:
-    processor_id: add_url
-    weights:
-      preprocess_index: -30
-    settings: {  }
+    plugin_id: add_url
+    settings:
+      weights:
+        preprocess_index: -30
   language:
-    processor_id: language
-    weights:
-      preprocess_index: -50
-    settings: {  }
+    plugin_id: language
+    settings:
+      weights:
+        preprocess_index: -50
 options:
   cron_limit: -1
   index_directly: false
-datasources:
-  - 'entity:entity_test'
-datasource_configs: {  }
-tracker: default
-tracker_config: {  }
+datasource_settings:
+  'entity:entity_test':
+    plugin_id: 'entity:entity_test'
+    settings: {  }
+tracker_settings:
+  'default':
+    plugin_id: default
+    settings: { }
 server: solr_search_server
 status: true
 langcode: en
diff --git a/tests/src/Kernel/SearchApiSolrTest.php b/tests/src/Kernel/SearchApiSolrTest.php
index e62bea3..df4a70a 100644
--- a/tests/src/Kernel/SearchApiSolrTest.php
+++ b/tests/src/Kernel/SearchApiSolrTest.php
@@ -10,11 +10,12 @@ namespace Drupal\Tests\search_api_solr\Kernel;
 use Drupal\search_api\Entity\Index;
 use Drupal\search_api\Entity\Server;
 use Drupal\search_api\Query\ResultSetInterface;
+use Drupal\search_api\Utility;
 use Drupal\Tests\search_api_db\Kernel\BackendTest;
 
 /**
  * Tests index and search capabilities using the Solr search backend.
- * 
+ *
  * @group search_api_solr
  */
 class SearchApiSolrTest extends BackendTest {
@@ -62,7 +63,7 @@ class SearchApiSolrTest extends BackendTest {
 
     $this->installConfig(array('search_api_test_solr'));
 
-    // Because this is a EntityUnitTest, the routing isn't built by default, so
+    // Because this is a kernel test, the routing isn't built by default, so
     // we have to force it.
     \Drupal::service('router.builder')->rebuild();
 
@@ -73,8 +74,15 @@ class SearchApiSolrTest extends BackendTest {
         $this->solrAvailable = TRUE;
       }
     }
-    catch (\Exception $e) {
-    }
+    catch (\Exception $e) {}
+  }
+
+  /**
+   * Clear the index after every test.
+   */
+  public function tearDown() {
+    $this->clearIndex();
+    parent::tearDown();
   }
 
   /**
@@ -86,11 +94,64 @@ class SearchApiSolrTest extends BackendTest {
       parent::testFramework();
     }
     else {
-      $this->pass('Error: The Solr instance could not be found. Please enable a multi-core one on http://localhost:8983/solr/d8');
+      $this->assertTrue(TRUE, 'Error: The Solr instance could not be found. Please enable a multi-core one on http://localhost:8983/solr/d8');
     }
   }
 
   /**
+   * Tests facets.
+   */
+  public function testFacets() {
+    $this->insertExampleContent();
+    $this->indexItems($this->indexId);
+
+    // Create a query object.
+    $query = Utility::createQuery($this->getIndex());
+
+    // Add a condition on the query object, to filter on category.
+    $conditions = $query->createConditionGroup('OR', array('facet:category'));
+    $conditions->addCondition('category', 'article_category');
+    $query->addConditionGroup($conditions);
+
+    // Add facet to the query.
+    $facets['category'] = array(
+      'field' => 'category',
+      'limit' => 10,
+      'min_count' => 1,
+      'missing' => TRUE,
+      'operator' => 'or',
+    );
+    $query->setOption('search_api_facets', $facets);
+
+    // Get the result.
+    $results = $query->execute();
+
+    $expected_results = array(
+      'entity:entity_test/4:en',
+      'entity:entity_test/5:en',
+    );
+
+    // Asserts that the result count is correct, as well as that the entities 4
+    // and 5 returned. And that the added condition actually filtered out the
+    // results so that the category of the returned results is article_category.
+    $this->assertEquals($expected_results, array_keys($results->getResultItems()));
+    $this->assertEquals(array('article_category'), $results->getResultItems()['entity:entity_test/4:en']->getField('category')->getValues());
+    $this->assertEquals(array('article_category'), $results->getResultItems()['entity:entity_test/5:en']->getField('category')->getValues());
+    $this->assertEquals(2, $results->getResultCount(), 'OR facets query returned correct number of results.');
+
+    $expected = array(
+      array('count' => 2, 'filter' => '"article_category"'),
+      array('count' => 2, 'filter' => '"item_category"'),
+      array('count' => 1, 'filter' => '!'),
+    );
+    $category_facets = $results->getExtraData('search_api_facets')['category'];
+    usort($category_facets, array($this, 'facetCompare'));
+
+    // Asserts that the returned facets are those that we expected.
+    $this->assertEquals($expected, $category_facets, 'Correct OR facets were returned');
+  }
+
+  /**
    * {@inheritdoc}
    */
   protected function indexItems($index_id) {
@@ -103,6 +164,7 @@ class SearchApiSolrTest extends BackendTest {
    * {@inheritdoc}
    */
   protected function clearIndex() {
+    /** @var \Drupal\search_api\IndexInterface $index */
     $index = Index::load($this->indexId);
     $index->clear();
     // Deleting items take at least 1 second for Solr to parse it so that drupal
@@ -151,7 +213,7 @@ class SearchApiSolrTest extends BackendTest {
     sleep(2);
     $query = $this->buildSearch();
     $results = $query->execute();
-    $this->assertEqual($results->getResultCount(), 0, 'Clearing the server worked correctly.');
+    $this->assertEquals(0, $results->getResultCount(), 'Clearing the server worked correctly.');
   }
 
   /**