--- /dev/null
+<?php
+
+namespace Drupal\Tests\block\Functional;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Tests the block system with admin themes.
+ *
+ * @group block
+ */
+class BlockAdminThemeTest extends BrowserTestBase {
+
+ /**
+ * Modules to install.
+ *
+ * @var array
+ */
+ public static $modules = ['block', 'contextual'];
+
+ /**
+ * Check for the accessibility of the admin theme on the block admin page.
+ */
+ public function testAdminTheme() {
+ // Create administrative user.
+ $admin_user = $this->drupalCreateUser(['administer blocks', 'administer themes']);
+ $this->drupalLogin($admin_user);
+
+ // Ensure that access to block admin page is denied when theme is not
+ // installed.
+ $this->drupalGet('admin/structure/block/list/bartik');
+ $this->assertResponse(403);
+
+ // Install admin theme and confirm that tab is accessible.
+ \Drupal::service('theme_handler')->install(['bartik']);
+ $edit['admin_theme'] = 'bartik';
+ $this->drupalPostForm('admin/appearance', $edit, t('Save configuration'));
+ $this->drupalGet('admin/structure/block/list/bartik');
+ $this->assertResponse(200);
+ }
+
+ /**
+ * Ensure contextual links are disabled in Seven theme.
+ */
+ public function testSevenAdminTheme() {
+ // Create administrative user.
+ $admin_user = $this->drupalCreateUser([
+ 'access administration pages',
+ 'administer themes',
+ 'access contextual links',
+ 'view the administration theme',
+ ]);
+ $this->drupalLogin($admin_user);
+
+ // Install admin theme and confirm that tab is accessible.
+ \Drupal::service('theme_handler')->install(['seven']);
+ $edit['admin_theme'] = 'seven';
+ $this->drupalPostForm('admin/appearance', $edit, t('Save configuration'));
+
+ // Define our block settings.
+ $settings = [
+ 'theme' => 'seven',
+ 'region' => 'header',
+ ];
+
+ // Place a block.
+ $block = $this->drupalPlaceBlock('local_tasks_block', $settings);
+
+ // Open admin page.
+ $this->drupalGet('admin');
+
+ // Check if contextual link classes are unavailable.
+ $this->assertNoRaw('<div data-contextual-id="block:block=' . $block->id() . ':langcode=en"></div>');
+ $this->assertNoRaw('contextual-region');
+ }
+
+}