diff --git a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
index a68392f..97a0aa2 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
@@ -179,7 +179,7 @@ protected function installSchema($module, $table) {
     Database::getConnection()->schema()->createTable($table, $schema);
     // We need to refresh the schema cache, as any call to drupal_get_schema()
     // would not know of/return the schema otherwise.
-    // @todo Very expensive. Refactor the Schema API to make this obsolete.
+    // @todo Refactor Schema API to make this obsolete.
     drupal_get_schema(NULL, TRUE);
   }
 
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/Tests/DrupalUnitTestBaseTest.php b/core/modules/simpletest/lib/Drupal/simpletest/Tests/DrupalUnitTestBaseTest.php
index 8cac15f..5813ffd 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/Tests/DrupalUnitTestBaseTest.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/Tests/DrupalUnitTestBaseTest.php
@@ -77,7 +77,7 @@ function testEnableModulesInstall() {
     $module = 'filter';
     $table = 'filter';
 
-    // @todo Heh. Remove after configuration system conversion.
+    // @todo Remove after configuration system conversion.
     $this->enableModules(array('system'), FALSE);
     $this->installSchema('system', 'variable');
 
@@ -95,7 +95,7 @@ function testEnableModulesInstall() {
     // Enable the module.
     $this->enableModules(array($module));
 
-    // Verify that the module does not exist yet.
+    // Verify that the enabled module exists.
     $this->assertTrue(module_exists($module), "$module module found.");
     $list = module_list();
     $this->assertTrue(in_array($module, $list), "$module module in module_list() found.");
@@ -118,7 +118,9 @@ function testEnableModulesInstallMultiple() {
     // Field retrieves entity type plugins, and EntityTypeManager calls into
     // hook_entity_info_alter(). If both modules would be first enabled together
     // instead of each on its own, then Node module's alter implementation
-    // would be called and this simply blows up.
+    // would be called and this simply blows up. To further complicate matters,
+    // additionally install Comment module, whose entity bundles depend on node
+    // types.
     $this->enableModules(array('field', 'node', 'comment'));
     $this->pass('Comment module was installed.');
   }
@@ -133,6 +135,7 @@ function testEnableModulesInstallContainer() {
     $this->enableModules(array('field_sql_storage', 'field', 'node'));
     // Perform an entity query against node.
     $query = entity_query('node');
+    // Disable node access checks, since User module is not enabled.
     $query->accessCheck(FALSE);
     $query->condition('nid', 1);
     $query->execute();