Issue #3376566 by kunal.sachdev, sakthi_dev, divya.sejekan, Nitin shrivastava,...

Issue #3376566 by kunal.sachdev, sakthi_dev, divya.sejekan, Nitin shrivastava, djsagar, smustgrave, nod_, longwave, quietone, catch: Display the page title, even if "0" in olivero

core/modules/system/tests/src/Functional/Theme/NodeTitleTestBase.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\system\Functional\Theme;
+
+use Drupal\Tests\node\Functional\NodeTestBase;
+
+/**
+ * Tests node title for a theme.
+ */
+abstract class NodeTitleTestBase extends NodeTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  protected static $modules = ['block'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    $this->drupalPlaceBlock('page_title_block');
+
+    $adminUser = $this->drupalCreateUser([
+      'administer themes',
+      'administer nodes',
+      'create article content',
+      'create page content',
+    ]);
+    $this->drupalLogin($adminUser);
+  }
+
+  /**
+   * Get the theme name.
+   *
+   * @return string
+   *   The theme to test.
+   */
+  protected function getTheme(): string {
+    return explode('\\', get_class($this))[2];
+  }
+
+  /**
+   * Creates one node with title 0 and tests if the node title has the correct value.
+   */
+  public function testNodeWithTitle0(): void {
+    $theme = $this->getTheme();
+    if ($theme !== $this->defaultTheme) {
+      $system_theme_config = $this->container->get('config.factory')
+        ->getEditable('system.theme');
+      $system_theme_config
+        ->set('default', $theme)
+        ->save();
+      \Drupal::service('theme_installer')->install([$theme]);
+    }
+
+    // Create "Basic page" content with title 0.
+    $settings = [
+      'title' => 0,
+    ];
+    $node = $this->drupalCreateNode($settings);
+    // Test that 0 appears as <title>.
+    $this->drupalGet('node/' . $node->id());
+    $this->assertSession()->titleEquals('0 | Drupal');
+    // Test that 0 appears in the template <h1>.
+    $this->assertSession()->elementTextEquals('xpath', '//h1', '0');
+  }
+
+}

core/themes/claro/tests/src/Functional/NodeTitleTest.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\claro\Functional;
+
+use Drupal\Tests\system\Functional\Theme\NodeTitleTestBase;
+
+/**
+ * Tests node title for claro.
+ *
+ * @group node
+ */
+class NodeTitleTest extends NodeTitleTestBase {
+
+}

core/themes/olivero/templates/content/page-title.html.twig

@@ -20,7 +20,7 @@
 %}
 
 {{ title_prefix }}
-{% if title|render|striptags|trim %}
+{% if (title|render|striptags|trim is not empty) %}
   <h1{{ title_attributes.addClass(classes) }}>{{ title }}</h1>
 {% endif %}
 {{ title_suffix }}

core/themes/olivero/tests/src/Functional/NodeTitleTest.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\olivero\Functional;
+
+use Drupal\Tests\system\Functional\Theme\NodeTitleTestBase;
+
+/**
+ * Tests node title for olivero.
+ *
+ * @group node
+ */
+class NodeTitleTest extends NodeTitleTestBase {
+
+}