diff --git a/.idea/misc.xml b/.idea/misc.xml
new file mode 100644
index 0000000..8662aa9
--- /dev/null
+++ b/.idea/misc.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" />
+</project>
\ No newline at end of file
diff --git a/core/modules/language/src/Tests/LanguageSwitchingTest.php b/core/modules/language/src/Tests/LanguageSwitchingTest.php
index c9ff8d0..828e943 100644
--- a/core/modules/language/src/Tests/LanguageSwitchingTest.php
+++ b/core/modules/language/src/Tests/LanguageSwitchingTest.php
@@ -283,6 +283,37 @@ function testLanguageBodyClass() {
 
   }
 
+  function testLanguageSwitcher() {
+    // Go to block layout.
+    $this->drupalGet('admin/structure/block');
+
+    // Check the link to add the block is there.
+    $language_switcher = $this->xpath('//*[@id="edit-category-system"]/div/ul/li[@class="language-blocklanguage-interface"]/a');
+    $this->assertTrue($language_switcher, 'Language  switcher is available.');
+
+    // Check the link has a tooltip.
+    $this->assertTrue($language_switcher[0]['title'], 'The tooltip is available.');
+
+    // Click to add the Language switcher.
+    $this->clickLink(t('Language switcher'));
+
+    // Post the block form.
+    $edit = array('region' => 'sidebar_first',);
+    $this->drupalPostForm(NULL, $edit, t('Save block'));
+
+    // Check the block has not been added.
+    $block = $this->xpath('//*[@id="blocks"]/tbody/tr[@class="draggable color-warning js-block-placed odd"]');
+    $this->assertFalse($block, 'The block is not added.');
+
+    // Check the message is being rendered.
+    // TODO: The system can show more than one message, check it in a loop.
+    $warning_messages = $this->xpath('//div[@class="region region-content"]/div[@class="messages messages--status"]/ul/li');
+    foreach($warning_messages as $warning) {
+      $warning_bool = ($warning->__toString() == 'The block Language Switcher cannot be added.')? true : false;
+    }
+    $this->assertTrue($warning_bool, 'Message to warning the user the block cannot be added.');
+  }
+
   /**
    * For authenticated users, the "active" class is set by JavaScript.
    *