diff --git a/composer.json b/composer.json
index eb2df1e8f825283906a85f7df677d1d063945b11..407701fe0499a8e821cc09e49cbdc5b483242302 100644
--- a/composer.json
+++ b/composer.json
@@ -25,6 +25,9 @@
     "php": ">=5.5.9",
     "composer/semver": "^1.0 || ^2.0 || ^3.0"
   },
+  "require-dev": {
+    "league/commonmark": "^1.6"
+  },
   "suggest": {
     "league/commonmark": "The PHP CommonMark parser is a robust, highly-extensible Markdown parser for PHP based on the CommonMark and Github-Flavored Markdown specifications."
   },
diff --git a/tests/src/Functional/FilterAdminTest.php b/tests/src/Functional/FilterAdminTest.php
index 3059f5bac31fd85755ed2676a4c41517a0ffd2bb..f888f4202c6a96776f8ab22a80323cdeb41f280e 100644
--- a/tests/src/Functional/FilterAdminTest.php
+++ b/tests/src/Functional/FilterAdminTest.php
@@ -2,6 +2,8 @@
 
 namespace Drupal\Tests\markdown\Functional;
 
+use Drupal\editor\EditorInterface;
+use Drupal\editor\Entity\Editor;
 use Drupal\filter\Entity\FilterFormat;
 use Drupal\filter\FilterFormatInterface;
 use Drupal\markdown\Plugin\Filter\FilterMarkdownInterface;
@@ -60,4 +62,40 @@ class FilterAdminTest extends MarkdownBrowserTestBase {
     $this->assertTrue($markdown->isEnabled());
   }
 
+  /**
+   * Tests creating a text format using CKEditor without the markdown filter.
+   */
+  public function testCreateTextFormatWithoutMarkdownFilter() {
+    // Enable the CKEditor5 module.
+    $this->container->get('module_installer')->install(['ckeditor5']);
+
+    // Add text format.
+    $this->drupalGet('admin/config/content/formats/add');
+
+    $format_id = $this->randomMachineName();
+    $edit = [
+      'format' => $format_id,
+      'name' => $this->randomMachineName(),
+      'editor[editor]' => 'ckeditor5',
+    ];
+    $this->submitForm($edit, 'Configure');
+
+    // Workaround for https://www.drupal.org/project/drupal/issues/3457717.
+    $edit = [
+      'editor[settings][toolbar][items]' => '["heading","bold","italic","drupalInsertImage"]',
+    ];
+    $this->submitForm($edit, 'Configure');
+    $this->submitForm([], 'Save configuration');
+    $this->assertSession()->statusCodeEquals(200);
+
+    // Check that the filter has been created.
+    $format = FilterFormat::load($format_id);
+    $this->assertInstanceof(FilterFormatInterface::class, $format);
+
+    // Check that CKEditor5 is enabled for this format.
+    $editor = Editor::load($format_id);
+    $this->assertInstanceof(EditorInterface::class, $editor);
+    $this->assertEquals('ckeditor5', $editor->getEditor());
+  }
+
 }