diff --git a/core/.eslintrc.json b/core/.eslintrc.json
index 6a6916b1a2c0aef4d1f49b21c18bf21c423f067b..7b1ed46abeca6b8ae943e070edf3cd77e47a8b29 100644
--- a/core/.eslintrc.json
+++ b/core/.eslintrc.json
@@ -21,6 +21,7 @@
"_": true,
"Cookies": true,
"Backbone": true,
+ "htmx": true,
"loadjs": true,
"Shepherd": true,
"Sortable": true,
diff --git a/core/core.libraries.yml b/core/core.libraries.yml
index 5ec851e898e7652d7f8ab474dfaf6ef3b138f4c4..48eb3b17a2309a17d532210ed39cc121dd86d74a 100644
--- a/core/core.libraries.yml
+++ b/core/core.libraries.yml
@@ -614,6 +614,17 @@ drupal.form:
- core/drupal.debounce
- core/once
+drupal.htmx:
+ version: VERSION
+ js:
+ misc/htmx/htmx-assets.js: {}
+ misc/htmx/htmx-behaviors.js: {}
+ dependencies:
+ - core/htmx
+ - core/drupal
+ - core/drupalSettings
+ - core/loadjs
+
drupal.machine-name:
version: VERSION
js:
diff --git a/core/core.services.yml b/core/core.services.yml
index 4372e6512c3e34c73f1db7c5174306690d134bd0..ce288b667a3a163a832cea23f52aaf927fcf34f4 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -1400,6 +1400,14 @@ services:
html_response.subscriber:
class: Drupal\Core\EventSubscriber\HtmlResponseSubscriber
arguments: ['@html_response.attachments_processor']
+ htmx_response.attachments_processor:
+ class: Drupal\Core\Render\Hypermedia\HtmxResponseAttachmentsProcessor
+ parent: html_response.attachments_processor
+ htmx.response_subscriber:
+ class: Drupal\Core\EventSubscriber\HtmxResponseSubscriber
+ arguments: [ '@request_stack', !service_closure '@htmx_response.attachments_processor' ]
+ tags:
+ - { name: event_subscriber }
finish_response_subscriber:
class: Drupal\Core\EventSubscriber\FinishResponseSubscriber
arguments: ['@language_manager', '@config.factory', '@page_cache_request_policy', '@page_cache_response_policy', '@cache_contexts_manager', '@datetime.time', '%http.response.debug_cacheability_headers%']
diff --git a/core/lib/Drupal/Core/EventSubscriber/HtmxResponseSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/HtmxResponseSubscriber.php
new file mode 100644
index 0000000000000000000000000000000000000000..2ec01b9e5dff23289bb3c832abd16b14779c757a
--- /dev/null
+++ b/core/lib/Drupal/Core/EventSubscriber/HtmxResponseSubscriber.php
@@ -0,0 +1,79 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Core\EventSubscriber;
+
+use Drupal\Component\Utility\Html;
+use Drupal\Core\Render\AttachmentsResponseProcessorInterface;
+use Drupal\Core\Render\HtmlResponse;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpKernel\Event\RequestEvent;
+use Symfony\Component\HttpKernel\Event\ResponseEvent;
+use Symfony\Component\HttpKernel\KernelEvents;
+
+/**
+ * Adds assets on responses to HTMX requests.
+ *
+ * @see \Drupal\Core\Render\Hypermedia\HtmxResponseAttachmentsProcessor
+ */
+class HtmxResponseSubscriber implements EventSubscriberInterface {
+
+ /**
+ * Constructs a HtmxResponseSubscriber object.
+ */
+ public function __construct(
+ protected readonly RequestStack $requestStack,
+ protected \Closure $attachmentsProcessor,
+ ) {}
+
+ /**
+ * Add assemble and attachments add HTMX attributes.
+ *
+ * @see \Drupal\Core\EventSubscriber\HtmlResponseSubscriber::onRespond
+ */
+ public function onRespond(ResponseEvent $event): void {
+ $response = $event->getResponse();
+ $requestHeaders = $this->requestStack->getCurrentRequest()->headers;
+ if (!($response instanceof HtmlResponse && $requestHeaders->has('HX-Request'))) {
+ // Only operate on HTML responses from an HTMX request.
+ return;
+ }
+ $processedResponse = $this->getAttachementsProcessor()->processAttachments($response);
+ if (!($processedResponse instanceof HtmlResponse)) {
+ throw new \TypeError("ResponseEvent::setResponse() requires an HtmlResponse object");
+ }
+ $event->setResponse($processedResponse);
+ }
+
+ protected function getAttachementsProcessor(): AttachmentsResponseProcessorInterface {
+ return ($this->attachmentsProcessor)();
+ }
+
+ /**
+ * Sets \Drupal\Component\Utility\Html::$isAjax to TRUE.
+ *
+ * @param \Symfony\Component\HttpKernel\Event\RequestEvent $event
+ * The request event, which contains the current request.
+ */
+ public function onRequest(RequestEvent $event) {
+ $requestHeaders = $event->getRequest()->headers;
+ // Pass to the Html class that the current request is an Ajax request.
+ if ($requestHeaders->has('HX-Request')) {
+ Html::setIsAjax(TRUE);
+ }
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function getSubscribedEvents(): array {
+ return [
+ // Our method needs to run before the HtmlResponseSubscriber(weight 0).
+ KernelEvents::RESPONSE => ['onRespond', 100],
+ KernelEvents::REQUEST => ['onRequest', 50],
+ ];
+ }
+
+}
diff --git a/core/lib/Drupal/Core/Render/Hypermedia/HtmxResponseAttachmentsProcessor.php b/core/lib/Drupal/Core/Render/Hypermedia/HtmxResponseAttachmentsProcessor.php
new file mode 100644
index 0000000000000000000000000000000000000000..8493c1c1b367179367d54068b7e87aa29c2b6a49
--- /dev/null
+++ b/core/lib/Drupal/Core/Render/Hypermedia/HtmxResponseAttachmentsProcessor.php
@@ -0,0 +1,95 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Core\Render\Hypermedia;
+
+use Drupal\Component\Serialization\Json;
+use Drupal\Component\Utility\UrlHelper;
+use Drupal\Core\Asset\AttachedAssetsInterface;
+use Drupal\Core\Render\AttachmentsInterface;
+use Drupal\Core\Render\HtmlResponse;
+use Drupal\Core\Render\HtmlResponseAttachmentsProcessor;
+
+/**
+ * Prepares attachment for HTMX powered responses.
+ *
+ * Extends the HTML response processor encode attachment data.
+ *
+ * @see \Drupal\Core\EventSubscriber\HtmxResponseSubscriber
+ * @see \Drupal\Core\Render\HtmlResponseAttachmentsProcessor::processAttachments
+ * @see core/misc/htmx-behaviors.js
+ */
+class HtmxResponseAttachmentsProcessor extends HtmlResponseAttachmentsProcessor {
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function processAssetLibraries(AttachedAssetsInterface $assets, array $placeholders) {
+ $request = $this->requestStack->getCurrentRequest();
+ if ($request->headers->has('HX-Page-State')) {
+ $uncompressed = UrlHelper::uncompressQueryParameter($request->headers->get('HX-Page-State'));
+ $libraries = explode(',', $uncompressed);
+ $assets->setAlreadyLoadedLibraries($libraries);
+ }
+ $settings = [];
+ $variables = [];
+ $maintenance_mode = defined('MAINTENANCE_MODE') || \Drupal::state()->get('system.maintenance_mode');
+
+ // Print styles - if present.
+ if (isset($placeholders['styles'])) {
+ // Optimize CSS if necessary, but only during normal site operation.
+ $optimize_css = !$maintenance_mode && $this->config->get('css.preprocess');
+ $variables['styles'] = $this->cssCollectionRenderer->render($this->assetResolver->getCssAssets($assets, $optimize_css, $this->languageManager->getCurrentLanguage()));
+ }
+
+ // Copy and adjust parent::processAssetLibraries to adjust and
+ // remove drupalSettings in line with
+ // AjaxResponseAttachmentsProcessor::buildAttachmentsCommands
+ // Print scripts - if any are present.
+ if (isset($placeholders['scripts']) || isset($placeholders['scripts_bottom'])) {
+ // Optimize JS if necessary, but only during normal site operation.
+ $optimize_js = !$maintenance_mode && $this->config->get('js.preprocess');
+ [$js_assets_header, $js_assets_footer] = $this->assetResolver
+ ->getJsAssets($assets, $optimize_js, $this->languageManager->getCurrentLanguage());
+ if (isset($js_assets_header['drupalSettings'])) {
+ $settings = $js_assets_header['drupalSettings']['data'];
+ unset($js_assets_header['drupalSettings']);
+ }
+ if (isset($js_assets_footer['drupalSettings'])) {
+ $settings = $js_assets_footer['drupalSettings']['data'];
+ unset($js_assets_footer['drupalSettings']);
+ }
+ if (empty($settings)) {
+ $settings = $assets->getSettings();
+ }
+ $variables['scripts'] = $this->jsCollectionRenderer->render($js_assets_header);
+ $variables['scripts_bottom'] = $this->jsCollectionRenderer->render($js_assets_footer);
+ unset($settings['path']);
+ $variables['settings'] = $settings;
+ }
+ /*
+ * @todo Update to use `#htmx` render array property when available.
+ */
+ return [
+ 'styles' => [],
+ 'scripts' => [],
+ 'scripts_bottom' => [
+ '#type' => 'container',
+ '#attributes' => [
+ 'data-hx-swap-oob' => 'beforeend:body',
+ ],
+ 'libraries' => [
+ '#type' => 'html_tag',
+ '#tag' => 'script',
+ '#attributes' => [
+ 'type' => 'application/json',
+ 'data-drupal-selector' => 'drupal-htmx-assets',
+ ],
+ '#value' => Json::encode($variables),
+ ],
+ ],
+ ];
+ }
+
+}
diff --git a/core/misc/htmx/htmx-assets.js b/core/misc/htmx/htmx-assets.js
new file mode 100644
index 0000000000000000000000000000000000000000..5829a4a682fb4493b76720ce6a7964b87e3ece3d
--- /dev/null
+++ b/core/misc/htmx/htmx-assets.js
@@ -0,0 +1,182 @@
+/**
+ * @file
+ * Adds needed assets to the current page.
+ */
+
+// JavaScript should be made compatible with libraries other than jQuery by
+// wrapping it in an anonymous closure.
+(function (Drupal, drupalSettings, once, loadjs, htmx) {
+ /**
+ * Helper function to merge two objects recursively.
+ *
+ * @param current
+ * The object to receive the merged values.
+ * @param sources
+ * The objects to merge into current.
+ *
+ * @return object
+ * The merged object.
+ *
+ * @see https://youmightnotneedjquery.com/#deep_extend
+ */
+ function mergeSettings(current, ...sources) {
+ if (!current) {
+ return {};
+ }
+
+ sources
+ .filter((obj) => Boolean(obj))
+ .forEach((obj) => {
+ Object.entries(obj).forEach(([key, value]) => {
+ switch (Object.prototype.toString.call(value)) {
+ case '[object Object]':
+ current[key] = current[key] || {};
+ current[key] = mergeSettings(current[key], value);
+ break;
+
+ case '[object Array]':
+ current[key] = mergeSettings(new Array(value.length), value);
+ break;
+
+ default:
+ current[key] = value;
+ }
+ });
+ });
+
+ return current;
+ }
+
+ /**
+ * Function to process and send the current ajax page state with each request.
+ *
+ * @param configRequestEvent
+ * HTMX event for request configuration.
+ */
+ function htmxDrupalData(configRequestEvent) {
+ const url = new URL(configRequestEvent.detail.path, document.location.href);
+ const origin = document.location.origin;
+ const sameHost = origin === url.origin;
+ if (sameHost) {
+ // We only need to add this data for htmx requests back to the site.
+ configRequestEvent.detail.headers['HX-Page-State'] =
+ drupalSettings.ajaxPageState.libraries;
+ // HTMX sets these header values using #id values.
+ // Swap in drupal data selectors as #id values are altered to be unique.
+ configRequestEvent.detail.headers['HX-Target'] =
+ configRequestEvent.detail.target.dataset.drupalSelector;
+ configRequestEvent.detail.headers['HX-Trigger'] =
+ configRequestEvent.detail.elt.dataset.drupalSelector;
+ }
+ }
+
+ /**
+ * Function to obtain, process, and attach new assets.
+ *
+ * @param {event} oobSwapEvent
+ * The event fired by HTMX.
+ */
+ function htmxDrupalAssetProcessor(oobSwapEvent) {
+ // Find any inserted assets.
+ const assetsTag = oobSwapEvent.detail.target.querySelector(
+ 'script[data-drupal-selector="drupal-htmx-assets"]',
+ );
+ if (!(assetsTag instanceof HTMLElement)) {
+ return;
+ }
+ // Parse assets and initialize container variables.
+ const assets = JSON.parse(assetsTag.textContent);
+ let cssItems = [];
+ let scriptItems = [];
+ let scriptBottomItems = [];
+ let paths = [];
+ if (assets.constructor.name === 'Object') {
+ // Variable assets should have properties 'styles', 'scripts,
+ // 'scripts_bottom', 'settings'. See
+ // HtmxResponseAttachmentsProcessor::processAssetLibraries
+ cssItems = new Map(
+ assets.styles.map((item) => [`css!${item['#attributes'].href}`, item]),
+ );
+ scriptItems = new Map(
+ assets.scripts.map((item) => [item['#attributes'].src, item]),
+ );
+ scriptBottomItems = new Map(
+ assets.scripts_bottom.map((item) => [item['#attributes'].src, item]),
+ );
+ mergeSettings(drupalSettings, assets.settings);
+ }
+ // Load CSS.
+ if (cssItems instanceof Map && cssItems.size > 0) {
+ // Fetch in parallel but load in sequence.
+ cssItems.forEach((value, key) => paths.push(key));
+ loadjs(paths, {
+ async: false,
+ before(path, linkElement) {
+ const item = cssItems.get(path);
+ Object.entries(item['#attributes']).forEach(
+ ([attributeKey, attributeValue]) => {
+ linkElement.setAttribute(attributeKey, attributeValue);
+ },
+ );
+ },
+ });
+ }
+ /* By default, loadjs appends the script to the head. When scripts
+ * are loaded via HTMX, their location has no impact on
+ * functionality. But, since Drupal loaded scripts can choose
+ * their parent element, we provide that option here for the sake of
+ * consistency.
+ */
+ if (scriptItems instanceof Map && scriptItems.size > 0) {
+ paths = [];
+ scriptItems.forEach((value, key) => paths.push(key));
+ // Load head JS.
+ // Fetch in parallel but load in sequence.
+ loadjs(paths, {
+ async: false,
+ before(path, scriptElement) {
+ const item = scriptItems.get(path);
+ Object.entries(item['#attributes']).forEach(
+ ([attributeKey, attributeValue]) => {
+ scriptElement.setAttribute(attributeKey, attributeValue);
+ },
+ );
+ },
+ });
+ }
+ if (scriptBottomItems instanceof Map && scriptBottomItems.size > 0) {
+ paths = [];
+ scriptBottomItems.forEach((value, key) => paths.push(key));
+ // Fetch in parallel but load in sequence.
+ loadjs(paths, {
+ async: false,
+ before(path, scriptElement) {
+ const item = scriptBottomItems.get(path);
+ Object.entries(item['#attributes']).forEach(
+ ([attributeKey, attributeValue]) => {
+ scriptElement.setAttribute(attributeKey, attributeValue);
+ },
+ );
+ document.body.appendChild(scriptElement);
+ // Return false to bypass loadjs' default DOM insertion
+ // mechanism.
+ return false;
+ },
+ });
+ }
+ // Any assets are now processed. Remove the found asset tag.
+ htmx.remove(assetsTag);
+ }
+
+ /* Initialize listeners. */
+
+ Drupal.behaviors.htmxAssets = {
+ attach: () => {
+ if (!once('htmxAssets', 'html').length) {
+ return;
+ }
+ window.addEventListener('htmx:configRequest', htmxDrupalData);
+ window.addEventListener('htmx:oobAfterSwap', htmxDrupalAssetProcessor);
+ },
+ };
+})(Drupal, drupalSettings, once, loadjs, htmx);
diff --git a/core/misc/htmx/htmx-behaviors.js b/core/misc/htmx/htmx-behaviors.js
new file mode 100644
index 0000000000000000000000000000000000000000..90a44426736d37e447e780b59d8eb23ad8cce4ff
--- /dev/null
+++ b/core/misc/htmx/htmx-behaviors.js
@@ -0,0 +1,32 @@
+/**
+ * @file
+ * Connect Drupal.behaviors to htmx inserted content.
+ */
+(function (Drupal, htmx, drupalSettings) {
+
+
+ // @todo replace with a custom event that will trigger once all the assets
+ // have been loaded.
+ htmx.on('htmx:load', (event) => {
+ Drupal.attachBehaviors(
+ // The attachBehaviors method searches within the context.
+ // We need to go up one level so that the loaded content is processed
+ // completely.
+ event.detail.elt?.parentElement,
+ drupalSettings,
+ );
+ });
+
+ // When htmx removes elements from the DOM, make sure they're detached first.
+ htmx.on('htmx:beforeSwap', (event) => {
+ Drupal.detachBehaviors(event.detail.elt, drupalSettings, 'unload');
+ });
+
+ /**
+ * @todo move that to ajax.js this is not necessary since htmx initializes the markup it adds to the page automatically.
+ * Also send new markup through htmx processing.
+ */
+ Drupal.behaviors.htmxProcess = {
+ attach: htmx.process,
+ };
+})(Drupal, htmx, drupalSettings);
diff --git a/core/modules/system/tests/modules/test_htmx/src/Controller/HtmxTestAttachmentsController.php b/core/modules/system/tests/modules/test_htmx/src/Controller/HtmxTestAttachmentsController.php
new file mode 100644
index 0000000000000000000000000000000000000000..b100d8adbea53f246c50b691c41f2320f6c9d6cf
--- /dev/null
+++ b/core/modules/system/tests/modules/test_htmx/src/Controller/HtmxTestAttachmentsController.php
@@ -0,0 +1,78 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\test_htmx\Controller;
+
+use Drupal\Core\Controller\ControllerBase;
+use Drupal\Core\Url;
+
+/**
+ * Returns responses for HTMX Test Attachments routes.
+ */
+final class HtmxTestAttachmentsController extends ControllerBase {
+
+ /**
+ * Builds the response.
+ *
+ * @return mixed[]
+ * A render array.
+ */
+ public function page(): array {
+ $url = Url::fromRoute('test_htmx.attachments.replace');
+ $build['replace'] = [
+ '#type' => 'button',
+ '#attributes' => [
+ 'name' => 'replace',
+ 'data-hx-get' => $url->toString(),
+ 'data-hx-select' => 'div.dropbutton-wrapper',
+ 'data-hx-target' => '[data-drupal-htmx-target]',
+ ],
+ '#value' => 'Click this',
+ '#context' => [
+ 'url' => $url,
+ ],
+ ];
+
+ $build['content'] = [
+ '#type' => 'container',
+ '#attached' => [
+ 'library' => [
+ 'core/drupal.htmx',
+ ],
+ ],
+ '#attributes' => [
+ 'data-drupal-htmx-target' => TRUE,
+ 'class' => ['htmx-test-container'],
+ ],
+ ];
+
+ return $build;
+ }
+
+ /**
+ * Builds the HTMX response.
+ *
+ * @return mixed[]
+ * A render array.
+ */
+ public function replace(): array {
+ $build['content'] = [
+ '#type' => 'dropbutton',
+ '#dropbutton_type' => 'small',
+ '#links' => [
+ 'simple_form' => [
+ 'title' => $this->t('Sample link 1'),
+ 'url' => Url::fromRoute('system.timezone'),
+ ],
+ 'demo' => [
+ 'title' => $this->t('Sample link 2'),
+ 'url' => Url::fromRoute('<front>'),
+ ],
+ ],
+ ];
+
+ return $build;
+ }
+
+}
diff --git a/core/modules/system/tests/modules/test_htmx/test_htmx.info.yml b/core/modules/system/tests/modules/test_htmx/test_htmx.info.yml
new file mode 100644
index 0000000000000000000000000000000000000000..713f8a551a5baa2809c4cd4758990afc0113952c
--- /dev/null
+++ b/core/modules/system/tests/modules/test_htmx/test_htmx.info.yml
@@ -0,0 +1,5 @@
+name: 'HTMX Test Fixtures'
+type: module
+description: 'Test fixtures for HTMX integration'
+package: Testing
+core_version_requirement: ^11
diff --git a/core/modules/system/tests/modules/test_htmx/test_htmx.routing.yml b/core/modules/system/tests/modules/test_htmx/test_htmx.routing.yml
new file mode 100644
index 0000000000000000000000000000000000000000..b6a82293bffc4df7f25cdd6d796c8215c88c6b9b
--- /dev/null
+++ b/core/modules/system/tests/modules/test_htmx/test_htmx.routing.yml
@@ -0,0 +1,17 @@
+test_htmx.attachments.page:
+ path: '/htmx-test-attachments/page'
+ defaults:
+ _title: 'Page'
+ _controller: '\Drupal\test_htmx\Controller\HtmxTestAttachmentsController::page'
+ requirements:
+ _permission: 'access content'
+
+test_htmx.attachments.replace:
+ path: '/htmx-test-attachments/replace'
+ defaults:
+ _title: 'Dropbutton'
+ _controller: '\Drupal\test_htmx\Controller\HtmxTestAttachmentsController::replace'
+ requirements:
+ _permission: 'access content'
+ options:
+ _htmx_route: 'true'
diff --git a/core/tests/Drupal/Nightwatch/Tests/htmx/htmxAssetLoadTest.js b/core/tests/Drupal/Nightwatch/Tests/htmx/htmxAssetLoadTest.js
new file mode 100644
index 0000000000000000000000000000000000000000..8af529d826e137f3a89e5f59760f2fdff1a748f9
--- /dev/null
+++ b/core/tests/Drupal/Nightwatch/Tests/htmx/htmxAssetLoadTest.js
@@ -0,0 +1,42 @@
+// The javascript that creates dropbuttons is not present on the /page at
+// initial load. If the once data property is added then the JS was loaded
+// and triggered on the inserted content.
+// @see \Drupal\test_htmx\Controller\HtmxTestAttachmentsController
+// @see core/modules/system/tests/modules/test_htmx/js/reveal-merged-settings.js
+module.exports = {
+ '@tags': ['core', 'htmx'],
+ before(browser) {
+ browser.drupalInstall({
+ setupFile: 'core/tests/Drupal/TestSite/HtmxAssetLoadTestSetup.php',
+ installProfile: 'minimal',
+ });
+ },
+ afterEach(browser) {
+ browser.drupalLogAndEnd({ onlyOnError: true });
+ },
+ after(browser) {
+ browser.drupalUninstall();
+ },
+
+ 'Asset Load': (browser) => {
+ // Load the route htmx will request and confirm the markup we will be looking
+ // for is present in the source markup.
+ browser
+ .drupalRelativeURL('/htmx-test-attachments/replace')
+ .waitForElementVisible('body', 1000)
+ .assert.elementPresent('script[src*="dropbutton.js"]');
+ // Now load the page with the htmx enhanced button and verify the absence
+ // of the markup to be inserted. Click the button
+ // and check for inserted javascript and markup.
+ browser
+ .drupalRelativeURL('/htmx-test-attachments/page')
+ .waitForElementVisible('body', 1000)
+ .assert.not.elementPresent('script[src*="dropbutton.js"]')
+ .waitForElementVisible('[name="replace"]', 1000)
+ .pause(1000)
+ .click('[name="replace"]')
+ .waitForElementVisible('div.dropbutton-wrapper', 60000)
+ .waitForElementVisible('div[data-once="dropbutton"]', 60000)
+ .assert.elementPresent('script[src*="dropbutton.js"]');
+ },
+};
diff --git a/core/tests/Drupal/TestSite/HtmxAssetLoadTestSetup.php b/core/tests/Drupal/TestSite/HtmxAssetLoadTestSetup.php
new file mode 100644
index 0000000000000000000000000000000000000000..03bb3fbdb113060d23eb3bcbad0fd3bcc67581fd
--- /dev/null
+++ b/core/tests/Drupal/TestSite/HtmxAssetLoadTestSetup.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\TestSite;
+
+use Drupal\Core\Extension\ModuleInstallerInterface;
+use Drupal\Core\Extension\ThemeInstallerInterface;
+
+/**
+ * Setup file used by tests/src/Nightwatch/Tests/htmxAssetLoadTest.js.
+ *
+ * @see \Drupal\Tests\Scripts\TestSiteApplicationTest
+ */
+class HtmxAssetLoadTestSetup implements TestSetupInterface {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function setup(): void {
+ // Install Olivero and set it as the default theme.
+ $theme_installer = \Drupal::service('theme_installer');
+ assert($theme_installer instanceof ThemeInstallerInterface);
+ $theme_installer->install(['olivero'], TRUE);
+ $system_theme_config = \Drupal::configFactory()->getEditable('system.theme');
+ $system_theme_config->set('default', 'olivero')->save();
+
+ // Install required modules.
+ $module_installer = \Drupal::service('module_installer');
+ assert($module_installer instanceof ModuleInstallerInterface);
+ $module_installer->install(['test_htmx']);
+ }
+
+}