--- /dev/null
+<?php
+
+namespace Drupal\Tests\search\Functional;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Tests that the search preprocessing uses the correct language code.
+ *
+ * @group search
+ */
+class SearchPreprocessLangcodeTest extends BrowserTestBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ protected static $modules = ['node', 'search', 'search_langcode_test'];
+
+ /**
+ * Test node for searching.
+ *
+ * @var \Drupal\node\NodeInterface
+ */
+ protected $node;
+
+ protected function setUp() {
+ parent::setUp();
+
+ $this->drupalCreateContentType(['type' => 'page', 'name' => 'Basic page']);
+
+ $web_user = $this->drupalCreateUser([
+ 'create page content',
+ 'edit own page content',
+ 'search content',
+ 'use advanced search',
+ ]);
+ $this->drupalLogin($web_user);
+ }
+
+ /**
+ * Tests that hook_search_preprocess() returns the correct langcode.
+ */
+ public function testPreprocessLangcode() {
+ // Create a node.
+ $this->node = $this->drupalCreateNode(['body' => [[]], 'langcode' => 'en']);
+
+ // First update the index. This does the initial processing.
+ $this->container->get('plugin.manager.search')->createInstance('node_search')->updateIndex();
+
+ // Then, run the shutdown function. Testing is a unique case where indexing
+ // and searching has to happen in the same request, so running the shutdown
+ // function manually is needed to finish the indexing process.
+ search_update_totals();
+
+ // Search for the additional text that is added by the preprocess
+ // function. If you search for text that is in the node, preprocess is
+ // not invoked on the node during the search excerpt generation.
+ $edit = ['or' => 'Additional text'];
+ $this->drupalPostForm('search/node', $edit, 'edit-submit--2');
+
+ // Checks if the langcode message has been set by hook_search_preprocess().
+ $this->assertText('Langcode Preprocess Test: en');
+ }
+
+ /**
+ * Tests stemming for hook_search_preprocess().
+ */
+ public function testPreprocessStemming() {
+ // Create a node.
+ $this->node = $this->drupalCreateNode([
+ 'title' => 'we are testing',
+ 'body' => [[]],
+ 'langcode' => 'en',
+ ]);
+
+ // First update the index. This does the initial processing.
+ $this->container->get('plugin.manager.search')->createInstance('node_search')->updateIndex();
+
+ // Then, run the shutdown function. Testing is a unique case where indexing
+ // and searching has to happen in the same request, so running the shutdown
+ // function manually is needed to finish the indexing process.
+ search_update_totals();
+
+ // Search for the title of the node with a POST query.
+ $edit = ['or' => 'testing'];
+ $this->drupalPostForm('search/node', $edit, 'edit-submit--2');
+
+ // Check if the node has been found.
+ $this->assertText('Search results');
+ $this->assertText('we are testing');
+
+ // Search for the same node using a different query.
+ $edit = ['or' => 'test'];
+ $this->drupalPostForm('search/node', $edit, 'edit-submit--2');
+
+ // Check if the node has been found.
+ $this->assertText('Search results');
+ $this->assertText('we are testing');
+ }
+
+}