diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
index b03a2c8..e90e407 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
@@ -148,16 +148,25 @@ function testBlock() {
    * Tests that the block form has a theme selector when not passed via the URL.
    */
   public function testBlockThemeSelector() {
-    // Select the 'Powered by Drupal' block to be configured and moved.
-    $block = array();
-    $block['machine_name'] = strtolower($this->randomName(8));
-    $block['theme'] = $this->container->get('config.factory')->get('system.theme')->get('default');
-    $block['region'] = 'header';
-
-    $this->drupalPost('admin/structure/block/add/system_powered_by_block', $block, t('Save block'));
-    $this->assertText(t('The block configuration has been saved.'));
-    $elements = $this->xpath('//div[@id = :id]', array(':id' => drupal_html_id('block-' . $block['machine_name'])));
-    $this->assertTrue(!empty($elements), 'The block was found.');
+    // Enable all themes.
+    theme_enable(array('bartik', 'seven'));
+    $theme_settings = $this->container->get('config.factory')->get('system.theme');
+    foreach (array('bartik', 'stark', 'seven') as $theme) {
+      // Select the 'Powered by Drupal' block to be placed.
+      $block = array();
+      $block['machine_name'] = strtolower($this->randomName(8));
+      $block['theme'] = $theme;
+      $block['region'] = 'content';
+      $this->drupalPost('admin/structure/block/add/system_powered_by_block', $block, t('Save block'));
+      $this->assertText(t('The block configuration has been saved.'));
+      $this->assertUrl('admin/structure/block/list/' . $theme . '?block-placement=' . drupal_html_class($theme . ':' . $block['machine_name']));
+
+      // Set the default theme and ensure the block is placed.
+      $theme_settings->set('default', $theme)->save();
+      $this->drupalGet('');
+      $elements = $this->xpath('//div[@id = :id]', array(':id' => drupal_html_id('block-' . $block['machine_name'])));
+      $this->assertTrue(!empty($elements), 'The block was found.');
+    }
   }
 
   /**
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index 1ebccca..5e32613 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -2377,7 +2377,11 @@ protected function assertUrl($path, array $options = array(), $message = '', $gr
       ));
     }
     $options['absolute'] = TRUE;
-    return $this->assertEqual($this->getUrl(), $this->container->get('url_generator')->generateFromPath($path, $options), $message, $group);
+    // Paths in query strings can be encoded or decoded with no functional
+    // difference, decode them for comparison purposes.
+    $actual_url = urldecode($this->getUrl());
+    $expected_url = urldecode($this->container->get('url_generator')->generateFromPath($path, $options));
+    return $this->assertEqual($actual_url, $expected_url, $message, $group);
   }
 
   /**