BlockInstallTest.php

<?php

namespace Drupal\Tests\block\Functional;

use Drupal\Tests\BrowserTestBase;

/**
 * Tests block module's installation.
 *
 * @group block
 */
class BlockInstallTest extends BrowserTestBase {
  
  /**
   * {@inheritdoc}
   */
  protected $defaultTheme = 'stark';
  public function testCacheTagInvalidationUponInstallation() {
    // Warm the page cache.
    $this->drupalGet('');
    $this->assertNoText('Powered by Drupal');
    $this->assertSession()
      ->responseHeaderNotContains('X-Drupal-Cache-Tags', 'config:block_list');
    // Install the block module, and place the "Powered by Drupal" block.
    $this->container
      ->get('module_installer')
      ->install([
      'block',
      'shortcut',
    ]);
    $this->rebuildContainer();
    $this->container
      ->get('router.builder')
      ->rebuild();
    $this->drupalPlaceBlock('system_powered_by_block');
    // Check the same page, block.module's hook_install() should have
    // invalidated the 'rendered' cache tag to make blocks show up.
    $this->drupalGet('');
    $this->assertCacheTag('config:block_list');
    $this->assertText('Powered by Drupal');
  }

}