diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
index 40f1d12..c607973 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
@@ -391,21 +391,20 @@ function testBlockModuleDisable() {
     $manager = $this->container->get('plugin.manager.block');
     $manager->clearCachedDefinitions();
 
-    // Add a test block.
-    $plugin = $manager->getDefinition('test_cache');
-    $block = array();
-    $block['id'] = 'test_cache';
-    $block['machine_name'] = $this->randomName(8);
-    $block['theme'] = variable_get('theme_default', 'stark');
-    $block['region'] = 'header';
-    $this->drupalPost('admin/structure/block/manage/' . $block['id'] . '/' . $block['theme'], array('machine_name' => $block['machine_name'], 'region' => $block['region']), t('Save block'));
-
-    // Confirm that the block is displayed on the front page.
+    // Add test blocks in different regions and confirm they are displayed.
+    $blocks = array();
+    $regions = array('sidebar_first', 'content', 'footer');
+    foreach ($regions as $region) {
+      $blocks[$region] = $this->drupalPlaceBlock('test_cache', array('region' => $region));
+    }
     $this->drupalGet('');
-    $this->assertText('Test block caching');
+    foreach ($regions as $region) {
+      $this->assertText($blocks[$region]['subject']);
+    }
 
     // Disable the block test module and refresh the definitions cache.
     module_disable(array('block_test'), FALSE);
+    $this->assertFalse(module_exists('block_test'), 'Test block module disabled.');
     $manager->clearCachedDefinitions();
 
     // Ensure that the block administration page still functions as expected.
@@ -415,7 +414,9 @@ function testBlockModuleDisable() {
     $this->assertTitle(t('Blocks | Drupal'));
 
     // Ensure that the disabled module's block instance is not listed.
-    $this->assertNoText(t('Test block caching'));
+    foreach ($regions as $region) {
+      $this->assertNoText($blocks[$region]['subject']);
+    }
 
     // Ensure that the disabled module's block plugin is no longer available.
     $this->drupalGet('admin/structure/block/list/block_plugin_ui:' . variable_get('theme_default', 'stark') . '/add');
@@ -424,17 +425,22 @@ function testBlockModuleDisable() {
     // Confirm that the block is no longer displayed on the front page.
     $this->drupalGet('');
     $this->assertResponse(200);
-    $this->assertNoText('Test block caching');
+    foreach ($regions as $region) {
+      $this->assertNoText($blocks[$region]['subject']);
+    }
 
-    // Confirm that a different block instance can still be enabled.
-    $block_id = 'system_powered_by_block';
+    // Confirm that a different block instance can still be enabled by
+    // submitting the block library form.
+    // Emulate a POST submission rather than using drupalPlaceBlock() to ensure
+    // that the form still functions as expected.
     $edit = array(
       'title' => $this->randomName(8),
       'machine_name' => $this->randomName(8),
       'region' => 'sidebar_first',
     );
-    $this->drupalPost('admin/structure/block/manage/' . $block_id . '/stark', $edit, t('Save block'));
+    $this->drupalPost('admin/structure/block/manage/system_powered_by_block/stark', $edit, t('Save block'));
     $this->assertText(t('The block configuration has been saved.'));
+    $this->assertText($edit['title']);
 
     // Update the weight of a block.
     $edit = array('blocks[0][weight]' => -1);
@@ -443,15 +449,31 @@ function testBlockModuleDisable() {
 
     // Re-enable the module and refresh the definitions cache.
     module_enable(array('block_test'), FALSE);
+    $this->assertTrue(module_exists('block_test'), 'Test block module re-enabled.');
     $manager->clearCachedDefinitions();
 
     // Reload the admin page and confirm the block can again be configured.
     $this->drupalGet('admin/structure/block');
-    $this->assertLinkByHref(url('admin/structure/block/manage/plugin.core.block.stark.' . $block['machine_name'] . '/stark/config'));
+    foreach ($regions as $region) {
+      $this->assertLinkByHref(url('admin/structure/block/manage/' . $blocks[$region]['config_id'] . '/stark/config'));
+    }
 
-    // Confirm that the block is again displayed on the front page.
+    // Confirm that the blocks are again displayed on the front page in the
+    // correct regions.
     $this->drupalGet('');
-    $this->assertText('Test block caching');
+    foreach ($regions as $region) {
+      // @todo Use a proper method for this.
+      $name_pieces = explode('.', $blocks[$region]['config_id']);
+      $machine_name = array_pop($name_pieces);
+      $xpath = $this->buildXPathQuery('//div[@class=:region-class]//div[@id=:block-id]/*', array(
+        ':region-class' => 'region region-' . drupal_html_class($region),
+        ':block-id' => 'block-' . strtr(strtolower($machine_name), '-', '_'),
+    ));
+      $this->assertFieldByXPath($xpath, NULL, format_string('Block %name found in the %region region.', array(
+        '%name' => $blocks[$region]['subject'],
+        '%region' => $region,
+      )));
+    }
   }
 
 }