--- /dev/null
+<?php
+
+namespace Drupal\Tests\config\Functional;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Tests config overrides do not appear on forms that extend ConfigFormBase.
+ *
+ * @group config
+ * @see \Drupal\Core\Form\ConfigFormBase
+ */
+class ConfigFormOverrideTest extends BrowserTestBase {
+
+ /**
+ * Tests that overrides do not affect forms.
+ */
+ public function testFormsWithOverrides() {
+ $this->drupalLogin($this->drupalCreateUser(['access administration pages', 'administer site configuration']));
+
+ $overridden_name = 'Site name global conf override';
+
+ // Set up an override.
+ $settings['config']['system.site']['name'] = (object) [
+ 'value' => $overridden_name,
+ 'required' => TRUE,
+ ];
+ $this->writeSettings($settings);
+
+ // Test that everything on the form is the same, but that the override
+ // worked for the actual site name.
+ $this->drupalGet('admin/config/system/site-information');
+ $this->assertTitle('Basic site settings | ' . $overridden_name);
+ $elements = $this->xpath('//input[@name="site_name"]');
+ $this->assertIdentical($elements[0]->getValue(), 'Drupal');
+
+ // Submit the form and ensure the site name is not changed.
+ $edit = [
+ 'site_name' => 'Custom site name',
+ ];
+ $this->drupalPostForm('admin/config/system/site-information', $edit, t('Save configuration'));
+ $this->assertTitle('Basic site settings | ' . $overridden_name);
+ $elements = $this->xpath('//input[@name="site_name"]');
+ $this->assertIdentical($elements[0]->getValue(), $edit['site_name']);
+ }
+
+}