--- /dev/null
+<?php
+
+namespace Drupal\Tests\user\FunctionalJavascript;
+
+use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+
+/**
+ * Tests user registration forms with additional fields.
+ *
+ * @group user
+ */
+class RegistrationWithUserFieldsTest extends WebDriverTestBase {
+
+ /**
+ * WebAssert object.
+ *
+ * @var \Drupal\Tests\WebAssert
+ */
+ protected $webAssert;
+
+ /**
+ * DocumentElement object.
+ *
+ * @var \Behat\Mink\Element\DocumentElement
+ */
+ protected $page;
+
+ /**
+ * {@inheritdoc}
+ */
+ public static $modules = ['field_test'];
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function setUp() {
+ parent::setUp();
+ $this->page = $this->getSession()->getPage();
+ $this->webAssert = $this->assertSession();
+ }
+
+ /**
+ * Tests Field API fields on user registration forms.
+ */
+ public function testRegistrationWithUserFields() {
+ // Create a field on 'user' entity type.
+ $field_storage = FieldStorageConfig::create([
+ 'field_name' => 'test_user_field',
+ 'entity_type' => 'user',
+ 'type' => 'test_field',
+ 'cardinality' => 1,
+ ]);
+ $field_storage->save();
+ $field = FieldConfig::create([
+ 'field_storage' => $field_storage,
+ 'label' => 'Some user field',
+ 'bundle' => 'user',
+ 'required' => TRUE,
+ ]);
+ $field->save();
+
+ entity_get_form_display('user', 'user', 'default')
+ ->setComponent('test_user_field', ['type' => 'test_field_widget'])
+ ->save();
+ $user_registration_form = entity_get_form_display('user', 'user', 'register');
+ $user_registration_form->save();
+
+ // Check that the field does not appear on the registration form.
+ $this->drupalGet('user/register');
+ $this->webAssert->pageTextNotContains($field->label());
+
+ // Have the field appear on the registration form.
+ $user_registration_form->setComponent('test_user_field', ['type' => 'test_field_widget'])->save();
+
+ $this->drupalGet('user/register');
+ $this->webAssert->pageTextContains($field->label());
+
+ // In order to check the server side validation the native browser
+ // validation for required fields needs to be circumvented.
+ $session = $this->getSession();
+ $session->executeScript("jQuery('#edit-test-user-field-0-value').prop('required', false);");
+
+ // Check that validation errors are correctly reported.
+ $name = $this->randomMachineName();
+ $this->page->fillField('edit-name', $name);
+ $this->page->fillField('edit-mail', $name . '@example.com');
+
+ $this->page->pressButton('edit-submit');
+ $this->webAssert->pageTextContains(t('@name field is required.', ['@name' => $field->label()]));
+
+ // Invalid input.
+ $this->page->fillField('edit-test-user-field-0-value', '-1');
+ $this->page->pressButton('edit-submit');
+ $this->webAssert->pageTextContains($field->label() . ' does not accept the value -1.');
+
+ // Submit with valid data.
+ $value = (string) mt_rand(1, 255);
+ $this->page->fillField('edit-test-user-field-0-value', $value);
+ $this->page->pressButton('edit-submit');
+ // Check user fields.
+ $accounts = $this->container->get('entity_type.manager')->getStorage('user')
+ ->loadByProperties(['name' => $name, 'mail' => $name . '@example.com']);
+ $new_user = reset($accounts);
+ $this->assertEquals($value, $new_user->test_user_field->value, 'The field value was correctly saved.');
+
+ // Check that the 'add more' button works.
+ $field_storage->setCardinality(FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED);
+ $field_storage->save();
+ $name = $this->randomMachineName();
+ $this->drupalGet('user/register');
+ $this->page->fillField('edit-name', $name);
+ $this->page->fillField('edit-mail', $name . '@example.com');
+ $this->page->fillField('test_user_field[0][value]', $value);
+ // Add two inputs.
+ $this->page->pressButton('test_user_field_add_more');
+ $this->webAssert->waitForElement('css', 'input[name="test_user_field[1][value]"]');
+ $this->page->fillField('test_user_field[1][value]', $value . '1');
+ $this->page->pressButton('test_user_field_add_more');
+ $this->webAssert->waitForElement('css', 'input[name="test_user_field[2][value]"]');
+ $this->page->fillField('test_user_field[2][value]', $value . '2');
+
+ // Submit with three values.
+ $this->page->pressButton('edit-submit');
+
+ // Check user fields.
+ $accounts = $this->container->get('entity_type.manager')
+ ->getStorage('user')
+ ->loadByProperties(['name' => $name, 'mail' => $name . '@example.com']);
+ $new_user = reset($accounts);
+ $this->assertEquals($value, $new_user->test_user_field[0]->value, t('The field value was correctly saved.'));
+ $this->assertEquals($value . '1', $new_user->test_user_field[1]->value, t('The field value was correctly saved.'));
+ $this->assertEquals($value . '2', $new_user->test_user_field[2]->value, t('The field value was correctly saved.'));
+ }
+
+}