diff -u b/core/modules/toolbar/src/Tests/ToolbarCacheContextsTest.php b/core/modules/toolbar/src/Tests/ToolbarCacheContextsTest.php
--- b/core/modules/toolbar/src/Tests/ToolbarCacheContextsTest.php
+++ b/core/modules/toolbar/src/Tests/ToolbarCacheContextsTest.php
@@ -68,29 +68,29 @@
    */
   public function testToolbarCacheContextsCaller() {
     // Test with default combination and permission to see toolbar.
-    $this->testToolbarCacheContexts(['user'], 'Expected cache contexts found for default combination and permission to see toolbar.');
+    $this->assertToolbarCacheContexts(['user'], 'Expected cache contexts found for default combination and permission to see toolbar.');
 
     // Test without user toolbar tab. User module is a required module so we have to
     // manually remove the user toolbar tab.
-    \Drupal::service('module_installer')->install(['toolbar_disable_user_toolbar']);
-    $this->testToolbarCacheContexts(['user.permissions'], 'Expected cache contexts found without user toolbar tab.');
+    $this->installModules(['toolbar_disable_user_toolbar']);
+    $this->assertToolbarCacheContexts(['user.permissions'], 'Expected cache contexts found without user toolbar tab.');
 
     // Test with the toolbar and contextual enabled.
-    \Drupal::service('module_installer')->install(['contextual']);
+    $this->installModules(['contextual']);
     $this->adminUser2 = $this->drupalCreateUser(array_merge($this->perms, ['access contextual links']));
-    $this->testToolbarCacheContexts(['user.permissions'], 'Expected cache contexts found with contextual module enabled.');
+    $this->assertToolbarCacheContexts(['user.permissions'], 'Expected cache contexts found with contextual module enabled.');
     \Drupal::service('module_installer')->uninstall(['contextual']);
 
     // Test with the tour module enabled.
-    \Drupal::service('module_installer')->install(['tour']);
+    $this->installModules(['tour']);
     $this->adminUser2 = $this->drupalCreateUser(array_merge($this->perms, ['access tour']));
-    $this->testToolbarCacheContexts(['user.permissions'], 'Expected cache contexts found with tour module enabled.');
+    $this->assertToolbarCacheContexts(['user.permissions'], 'Expected cache contexts found with tour module enabled.');
     \Drupal::service('module_installer')->uninstall(['tour']);
 
     // Test with shortcut module enabled.
-    \Drupal::service('module_installer')->install(['shortcut']);
+    $this->installModules(['shortcut']);
     $this->adminUser2 = $this->drupalCreateUser(array_merge($this->perms, ['access shortcuts', 'administer shortcuts']));
-    $this->testToolbarCacheContexts(['user'], 'Expected cache contexts found with shortcut module enabled.');
+    $this->assertToolbarCacheContexts(['user'], 'Expected cache contexts found with shortcut module enabled.');
   }
 
   /**
@@ -101,10 +101,7 @@
    * @param string $message
    *   (optional) A verbose message to output.
    */
-  private function testToolbarCacheContexts(array $cache_contexts, $message = NULL) {
-    // Caches have to be rebuilt since modules might have added some routes.
-    drupal_flush_all_caches();
-
+  protected function assertToolbarCacheContexts(array $cache_contexts, $message = NULL) {
     // Default cache contexts that should exist on all test cases.
     $default_cache_contexts = [
       'languages:language_interface',
@@ -126,2 +123,16 @@
 
+  /**
+   * Installs a given list of modules and rebuilds the cache.
+   *
+   * @param string[] $module_list
+   *   An array of module names.
+   */
+  protected function installModules(array $module_list) {
+    \Drupal::service('module_installer')->install($module_list);
+
+    // Caches have to be rebuilt since modules might have added some routes.
+    drupal_flush_all_caches();
+  }
+
+
 }