Issue #304540 by typhonius, BrockBoland, nabiyllin, RobLoach, marcingy,...

Issue #304540 by typhonius, BrockBoland, nabiyllin, RobLoach, marcingy, ravi.khetri, jyotisankar, sudhanshug, jaredsmith, nesta_: Disable themes when theme engine or base theme aren't available

core/modules/system/src/Controller/SystemController.php

@@ -245,8 +245,8 @@ public function themesPage() {
         // content has a common place in all themes.
         $theme->incompatible_region = !isset($theme->info['regions']['content']);
         $theme->incompatible_php = version_compare(phpversion(), $theme->info['php']) < 0;
-        // Confirmed that the base theme is available.
-        $theme->incompatible_base = isset($theme->info['base theme']) && !isset($themes[$theme->info['base theme']]);
+        // Confirm that all base themes are available.
+        $theme->incompatible_base = (isset($theme->info['base theme']) && !($theme->base_themes === array_filter($theme->base_themes)));
         // Confirm that the theme engine is available.
         $theme->incompatible_engine = isset($theme->info['engine']) && !isset($theme->owner);
       }

core/modules/system/src/Tests/System/ThemeTest.php

@@ -319,6 +319,9 @@ function testSwitchDefaultTheme() {
 
   /**
    * Test themes can't be installed when the base theme or engine is missing.
+   *
+   * Include test for themes that have a missing base theme somewhere further up
+   * the chain than the immediate base theme.
    */
   function testInvalidTheme() {
     // theme_page_test_system_info_alter() un-hides all hidden themes.
@@ -327,6 +330,7 @@ function testInvalidTheme() {
     $this->container->get('theme_handler')->reset();
     $this->drupalGet('admin/appearance');
     $this->assertText(t('This theme requires the base theme @base_theme to operate correctly.', array('@base_theme' => 'not_real_test_basetheme')));
+    $this->assertText(t('This theme requires the base theme @base_theme to operate correctly.', array('@base_theme' => 'test_invalid_basetheme')));
     $this->assertText(t('This theme requires the theme engine @theme_engine to operate correctly.', array('@theme_engine' => 'not_real_engine')));
     // Check for the error text of a theme with the wrong core version.
     $this->assertText("This theme is not compatible with Drupal 8.x. Check that the .info.yml file contains the correct 'core' value.");

core/modules/system/tests/themes/test_invalid_basetheme_sub/test_invalid_basetheme_sub.info.yml

+name: 'Theme test with valid base theme but no grandparent base theme'
+type: theme
+description: 'Test theme which has a non-existent base theme in the base chain.'
+version: VERSION
+core: 8.x
+base theme: test_invalid_basetheme