diff --git a/core/modules/system/src/Tests/Form/FormTest.php b/core/modules/system/src/Tests/Form/FormTest.php
index 098751a..8bafe7e 100644
--- a/core/modules/system/src/Tests/Form/FormTest.php
+++ b/core/modules/system/src/Tests/Form/FormTest.php
@@ -299,8 +299,7 @@ function testCheckboxProcessing() {
    * Tests validation of #type 'select' elements.
    */
   function testSelect() {
-    $form = $form_state = array();
-    $form = form_test_select($form, $form_state);
+    $form = \Drupal::formBuilder()->getForm('Drupal\form_test\Form\FormTestSelectForm');
     $error = '!name field is required.';
     $this->drupalGet('form-test/select');
 
diff --git a/core/modules/system/tests/modules/form_test/form_test.module b/core/modules/system/tests/modules/form_test/form_test.module
index 340c1f9..88d9245 100644
--- a/core/modules/system/tests/modules/form_test/form_test.module
+++ b/core/modules/system/tests/modules/form_test/form_test.module
@@ -39,18 +39,6 @@ function _form_test_submit_values_json($form, &$form_state) {
 }
 
 /**
- * Form builder for testing hook_form_alter() and hook_form_FORM_ID_alter().
- *
- * @deprecated Use \Drupal\form_test\alterForm()
- */
-function form_test_alter_form($form, &$form_state) {
-  // Elements can be added as needed for future testing needs, but for now,
-  // we're only testing alter hooks that do not require any elements added by
-  // this function.
-  return $form;
-}
-
-/**
  * Implements hook_form_FORM_ID_alter() on behalf of block.module.
  */
 function block_form_form_test_alter_form_alter(&$form, &$form_state) {
@@ -81,111 +69,6 @@ function system_form_form_test_alter_form_alter(&$form, &$form_state) {
 }
 
 /**
- * Form builder for testing drupal_validate_form().
- *
- * Serves for testing form processing and alterations by form validation
- * handlers, especially for the case of a validation error:
- * - form_set_value() should be able to alter submitted values in
- *   $form_state['values'] without affecting the form element.
- * - #element_validate handlers should be able to alter the $element in the form
- *   structure and the alterations should be contained in the rebuilt form.
- * - #validate handlers should be able to alter the $form and the alterations
- *   should be contained in the rebuilt form.
- *
- * @deprecated Use \Drupal\form_test\validateForm()
- */
-function form_test_validate_form($form, &$form_state) {
-  $object = new Callbacks();
-
-  $form['name'] = array(
-    '#type' => 'textfield',
-    '#title' => 'Name',
-    '#default_value' => '',
-    '#element_validate' => array(array($object, 'validateName')),
-  );
-  $form['submit'] = array(
-    '#type' => 'submit',
-    '#value' => 'Save',
-  );
-
-  // To simplify this test, enable form caching and use form storage to
-  // remember our alteration.
-  $form_state['cache'] = TRUE;
-
-  return $form;
-}
-
-/**
- * Form validation handler for form_test_validate_form().
- */
-function form_test_validate_form_validate(&$form, &$form_state) {
-  if ($form_state['values']['name'] == 'validate') {
-    // Alter the form element.
-    $form['name']['#value'] = '#value changed by #validate';
-    // Alter the submitted value in $form_state.
-    form_set_value($form['name'], 'value changed by form_set_value() in #validate', $form_state);
-    // Output the element's value from $form_state.
-    drupal_set_message(t('@label value: @value', array('@label' => $form['name']['#title'], '@value' => $form_state['values']['name'])));
-
-    // Trigger a form validation error to see our changes.
-    form_set_error('', $form_state);
-  }
-}
-
-/**
- * Form constructor to test the #required property.
- *
- * @deprecated Use \Drupal\form_test\validateRequiredForm()
- */
-function form_test_validate_required_form($form, &$form_state) {
-  $options = array('foo' => 'foo', 'bar' => 'bar');
-  $validate = array('form_test_validate_required_form_element_validate');
-
-  $form['textfield'] = array(
-    '#type' => 'textfield',
-    '#title' => 'Name',
-    '#required' => TRUE,
-    '#required_error' => t('Please enter a name.'),
-  );
-  $form['checkboxes'] = array(
-    '#type' => 'checkboxes',
-    '#title' => 'Checkboxes',
-    '#options' => $options,
-    '#required' => TRUE,
-    '#form_test_required_error' => t('Please choose at least one option.'),
-    '#element_validate' => $validate,
-  );
-  $form['select'] = array(
-    '#type' => 'select',
-    '#title' => 'Select',
-    '#options' => $options,
-    '#required' => TRUE,
-    '#form_test_required_error' => t('Please select something.'),
-    '#element_validate' => $validate,
-  );
-  $form['radios'] = array(
-    '#type' => 'radios',
-    '#title' => 'Radios',
-    '#options' => $options,
-    '#required' => TRUE,
-  );
-  $form['radios_optional'] = array(
-    '#type' => 'radios',
-    '#title' => 'Radios (optional)',
-    '#options' => $options,
-  );
-  $form['radios_optional_default_value_false'] = array(
-    '#type' => 'radios',
-    '#title' => 'Radios (optional, with a default value of FALSE)',
-    '#options' => $options,
-    '#default_value' => FALSE,
-  );
-  $form['actions'] = array('#type' => 'actions');
-  $form['actions']['submit'] = array('#type' => 'submit', '#value' => 'Submit');
-  return $form;
-}
-
-/**
  * Form element validation handler for 'Name' field in form_test_validate_required_form().
  */
 function form_test_validate_required_form_element_validate($element, &$form_state) {
@@ -196,100 +79,6 @@ function form_test_validate_required_form_element_validate($element, &$form_stat
 }
 
 /**
- * Form submission handler for form_test_validate_required_form().
- */
-function form_test_validate_required_form_submit($form, &$form_state) {
-  drupal_set_message('The form_test_validate_required_form form was submitted successfully.');
-}
-
-/**
- * Form constructor to test the #required property without #title.
- *
- * @deprecated Use \Drupal\form_test\validateRequiredFormNoTitle()
- */
-function form_test_validate_required_form_no_title($form, &$form_state) {
-  $form['textfield'] = array(
-    '#type' => 'textfield',
-    '#required' => TRUE,
-  );
-  $form['actions'] = array('#type' => 'actions');
-  $form['actions']['submit'] = array('#type' => 'submit', '#value' => 'Submit');
-  return $form;
-}
-
-/**
- * Form submission handler for form_test_validate_required_form_no_title().
- */
-function form_test_validate_required_form_no_title_submit($form, &$form_state) {
-  drupal_set_message('The form_test_validate_required_form_no_title form was submitted successfully.');
-}
-
-/**
- * Builds a simple form with a button triggering partial validation.
- *
- * @deprecated Use \Drupal\form_test\validateFormWithErrorSuppression()
- */
-function form_test_limit_validation_errors_form($form, &$form_state) {
-  $form['title'] = array(
-    '#type' => 'textfield',
-    '#title' => 'Title',
-    '#required' => TRUE,
-  );
-
-  $form['test'] = array(
-    '#title' => 'Test',
-    '#type' => 'textfield',
-    '#element_validate' => array('form_test_limit_validation_errors_element_validate_test'),
-  );
-  $form['test_numeric_index'] = array(
-    '#tree' => TRUE,
-  );
-  $form['test_numeric_index'][0] = array(
-    '#title' => 'Test (numeric index)',
-    '#type' => 'textfield',
-    '#element_validate' => array('form_test_limit_validation_errors_element_validate_test'),
-  );
-
-  $form['test_substring'] = array(
-    '#tree' => TRUE,
-  );
-  $form['test_substring']['foo'] = array(
-    '#title' => 'Test (substring) foo',
-    '#type' => 'textfield',
-    '#element_validate' => array('form_test_limit_validation_errors_element_validate_test'),
-  );
-  $form['test_substring']['foobar'] = array(
-    '#title' => 'Test (substring) foobar',
-    '#type' => 'textfield',
-    '#element_validate' => array('form_test_limit_validation_errors_element_validate_test'),
-  );
-
-  $form['actions']['partial'] = array(
-    '#type' => 'submit',
-    '#limit_validation_errors' => array(array('test')),
-    '#submit' => array('form_test_limit_validation_errors_form_partial_submit'),
-    '#value' => t('Partial validate'),
-  );
-  $form['actions']['partial_numeric_index'] = array(
-    '#type' => 'submit',
-    '#limit_validation_errors' => array(array('test_numeric_index', 0)),
-    '#submit' => array('form_test_limit_validation_errors_form_partial_submit'),
-    '#value' => t('Partial validate (numeric index)'),
-  );
-  $form['actions']['substring'] = array(
-    '#type' => 'submit',
-    '#limit_validation_errors' => array(array('test_substring', 'foo')),
-    '#submit' => array('form_test_limit_validation_errors_form_partial_submit'),
-    '#value' => t('Partial validate (substring)'),
-  );
-  $form['actions']['full'] = array(
-    '#type' => 'submit',
-    '#value' => t('Full validate'),
-  );
-  return $form;
-}
-
-/**
  * Form element validation handler for the 'test' element.
  */
 function form_test_limit_validation_errors_element_validate_test(&$element, &$form_state) {
@@ -299,54 +88,6 @@ function form_test_limit_validation_errors_element_validate_test(&$element, &$fo
 }
 
 /**
- * Form submit handler for the partial validation submit button.
- */
-function form_test_limit_validation_errors_form_partial_submit($form, $form_state) {
-  // The title has not been validated, thus its value - in case of the test case
-  // an empty string - may not be set.
-  if (!isset($form_state['values']['title']) && isset($form_state['values']['test'])) {
-    drupal_set_message('Only validated values appear in the form values.');
-  }
-}
-
-/**
- * Builds a simple form using the FAPI #pattern proterty.
- *
- * @deprecated Use \Drupal\form_test\validatePattern()
- */
-function form_test_pattern_form($form, &$form_state) {
-  $form['textfield'] = array(
-    '#type' => 'textfield',
-    '#title' => 'One digit followed by lowercase letters',
-    '#pattern' => '[0-9][a-z]+',
-  );
-  $form['tel'] = array(
-    '#type' => 'tel',
-    '#title' => 'Everything except numbers',
-    '#pattern' => '[^\d]*',
-  );
-  $form['password'] = array(
-    '#type' => 'password',
-    '#title' => 'Password',
-    '#pattern' => '[01]+',
-  );
-  $form['url'] = array(
-    '#type' => 'url',
-    '#title' => 'Client side validation',
-    '#decription' => 'Just client side validation, using the #pattern attribute.',
-    '#attributes' => array(
-      'pattern' => '.*foo.*',
-    ),
-    '#pattern' => 'ignored',
-  );
-  $form['submit'] = array(
-    '#type' => 'submit',
-    '#value' => 'Submit',
-  );
-  return $form;
-}
-
-/**
  * Create a header and options array. Helper function for callbacks.
  */
 function _form_test_tableselect_get_data() {
@@ -385,75 +126,6 @@ function _form_test_tableselect_get_data() {
 }
 
 /**
- * A multistep form for testing the form storage.
- *
- * It uses two steps for editing a virtual "thing". Any changes to it are saved
- * in the form storage and have to be present during any step. By setting the
- * request parameter "cache" the form can be tested with caching enabled, as
- * it would be the case, if the form would contain some #ajax callbacks.
- *
- * @see form_test_storage_form_submit()
- *
- * @deprecated Use \Drupal\form_test\testStorage()
- */
-function form_test_storage_form($form, &$form_state) {
-  if ($form_state['rebuild']) {
-    $form_state['input'] = array();
-  }
-  // Initialize
-  if (empty($form_state['storage'])) {
-    if (empty($form_state['input'])) {
-      $_SESSION['constructions'] = 0;
-    }
-    // Put the initial thing into the storage
-    $form_state['storage'] = array(
-      'thing' => array(
-        'title' => 'none',
-        'value' => '',
-      ),
-    );
-  }
-  // Count how often the form is constructed.
-  $_SESSION['constructions']++;
-  drupal_set_message("Form constructions: " . $_SESSION['constructions']);
-
-  $form['title'] = array(
-    '#type' => 'textfield',
-    '#title' => 'Title',
-    '#default_value' => $form_state['storage']['thing']['title'],
-    '#required' => TRUE,
-  );
-  $form['value'] = array(
-    '#type' => 'textfield',
-    '#title' => 'Value',
-    '#default_value' => $form_state['storage']['thing']['value'],
-    '#element_validate' => array('form_test_storage_element_validate_value_cached'),
-  );
-  $form['continue_button'] = array(
-    '#type' => 'button',
-    '#value' => 'Reset',
-    // Rebuilds the form without keeping the values.
-  );
-  $form['continue_submit'] = array(
-    '#type' => 'submit',
-    '#value' => 'Continue submit',
-    '#submit' => array('form_storage_test_form_continue_submit'),
-  );
-  $form['submit'] = array(
-    '#type' => 'submit',
-    '#value' => 'Save',
-  );
-
-  if (\Drupal::request()->get('cache')) {
-    // Manually activate caching, so we can test that the storage keeps working
-    // when it's enabled.
-    $form_state['cache'] = TRUE;
-  }
-
-  return $form;
-}
-
-/**
  * Form element validation handler for 'value' element in form_test_storage_form().
  *
  * Tests updating of cached form storage during validation.
@@ -478,18 +150,6 @@ function form_storage_test_form_continue_submit($form, &$form_state) {
 }
 
 /**
- * Form submit handler to finish multi-step form.
- */
-function form_test_storage_form_submit($form, &$form_state) {
-  drupal_set_message("Title: " . String::checkPlain($form_state['values']['title']));
-  drupal_set_message("Form constructions: " . $_SESSION['constructions']);
-  if (isset($form_state['storage']['thing']['changed'])) {
-    drupal_set_message("The thing has been changed.");
-  }
-  $form_state['redirect_route']['route_name'] = '<front>';
-}
-
-/**
  * A form for testing form labels and required marks.
  *
  * @deprecated Use \Drupal\form_test\testLabel()
@@ -582,227 +242,6 @@ function form_label_test_form() {
 }
 
 /**
- * Form builder for form_state_values_clean() test.
- *
- * @deprecated Use \Drupal\form_test\testFormStateClean()
- */
-function form_test_form_state_values_clean_form($form, &$form_state) {
-  // Build an example form containing multiple submit and button elements; not
-  // only on the top-level.
-  $form = array('#tree' => TRUE);
-  $form['foo'] = array('#type' => 'submit', '#value' => t('Submit'));
-  $form['bar'] = array('#type' => 'submit', '#value' => t('Submit'));
-  $form['beer'] = array('#type' => 'value', '#value' => 1000);
-  $form['baz']['foo'] = array('#type' => 'button', '#value' => t('Submit'));
-  $form['baz']['baz'] = array('#type' => 'submit', '#value' => t('Submit'));
-  $form['baz']['beer'] = array('#type' => 'value', '#value' => 2000);
-  return $form;
-}
-
-/**
- * Form submit handler for form_state_values_clean() test form.
- */
-function form_test_form_state_values_clean_form_submit($form, &$form_state) {
-  form_state_values_clean($form_state);
-  // This won't have a proper JSON header, but Drupal doesn't check for that
-  // anyway so this is fine until it's replaced with a JsonResponse.
-  print Json::encode($form_state['values']);
-  exit;
-}
-
-/**
- * Form constructor for the form_state_values_clean() test.
- *
- * @deprecated Use \Drupal\form_test\testFormStateCleanAdvanced()
- */
-function form_test_form_state_values_clean_advanced_form($form, &$form_state) {
-  // Build an example form containing a managed file and a submit form element.
-  $form['image'] = array(
-    '#type' => 'managed_file',
-    '#title' => t('Image'),
-    '#upload_location' => 'public://',
-    '#default_value' => 0,
-  );
-  $form['submit'] = array(
-    '#type' => 'submit',
-    '#value' => t('Submit'),
-  );
-  return $form;
-}
-
-/**
- * Form submission handler for form_test_form_state_values_clean_advanced_form().
- */
-function form_test_form_state_values_clean_advanced_form_submit($form, &$form_state) {
-  form_state_values_clean($form_state);
-  print t('You WIN!');
-  exit;
-}
-
-/**
- * Builds a form to test #type 'select' validation.
- *
- * @deprecated Use \Drupal\form_test\testSelect()
- */
-function form_test_select($form, &$form_state) {
-  $form['#submit'] = array('_form_test_submit_values_json');
-
-  $base = array(
-    '#type' => 'select',
-    '#options' => array('one' => 'one', 'two' => 'two', 'three' => 'three'),
-  );
-
-  $form['select'] = $base + array(
-    '#title' => '#default_value one',
-    '#default_value' => 'one',
-  );
-  $form['select_required'] = $base + array(
-    '#title' => '#default_value one, #required',
-    '#required' => TRUE,
-    '#default_value' => 'one',
-  );
-  $form['select_optional'] = $base + array(
-    '#title' => '#default_value one, not #required',
-    '#required' => FALSE,
-    '#default_value' => 'one',
-  );
-  $form['empty_value'] = $base + array(
-    '#title' => '#default_value one, #required, #empty_value 0',
-    '#required' => TRUE,
-    '#default_value' => 'one',
-    '#empty_value' => 0,
-  );
-  $form['empty_value_one'] = $base + array(
-    '#title' => '#default_value = #empty_value, #required',
-    '#required' => TRUE,
-    '#default_value' => 'one',
-    '#empty_value' => 'one',
-  );
-
-  $form['no_default'] = $base + array(
-    '#title' => 'No #default_value, #required',
-    '#required' => TRUE,
-  );
-  $form['no_default_optional'] = $base + array(
-    '#title' => 'No #default_value, not #required',
-    '#required' => FALSE,
-    '#description' => 'Should result in "one" because it is not required and there is no #empty_value requested, so default browser behavior of preselecting first option is in effect.',
-  );
-  $form['no_default_optional_empty_value'] = $base + array(
-    '#title' => 'No #default_value, not #required, #empty_value empty string',
-    '#empty_value' => '',
-    '#required' => FALSE,
-    '#description' => 'Should result in an empty string (due to #empty_value) because it is optional.',
-  );
-
-  $form['no_default_empty_option'] = $base + array(
-    '#title' => 'No #default_value, #required, #empty_option',
-    '#required' => TRUE,
-    '#empty_option' => '- Choose -',
-  );
-  $form['no_default_empty_option_optional'] = $base + array(
-    '#title' => 'No #default_value, not #required, #empty_option',
-    '#empty_option' => '- Dismiss -',
-    '#description' => 'Should result in an empty string (default of #empty_value) because it is optional.',
-  );
-
-  $form['no_default_empty_value'] = $base + array(
-    '#title' => 'No #default_value, #required, #empty_value 0',
-    '#required' => TRUE,
-    '#empty_value' => 0,
-    '#description' => 'Should never result in 0.',
-  );
-  $form['no_default_empty_value_one'] = $base + array(
-    '#title' => 'No #default_value, #required, #empty_value one',
-    '#required' => TRUE,
-    '#empty_value' => 'one',
-    '#description' => 'A mistakenly assigned #empty_value contained in #options should not be valid.',
-  );
-  $form['no_default_empty_value_optional'] = $base + array(
-    '#title' => 'No #default_value, not #required, #empty_value 0',
-    '#required' => FALSE,
-    '#empty_value' => 0,
-    '#description' => 'Should result in 0 because it is optional.',
-  );
-
-  $form['multiple'] = $base + array(
-    '#title' => '#multiple, #default_value two',
-    '#default_value' => array('two'),
-    '#multiple' => TRUE,
-  );
-  $form['multiple_no_default'] = $base + array(
-    '#title' => '#multiple, no #default_value',
-    '#multiple' => TRUE,
-  );
-  $form['multiple_no_default_required'] = $base + array(
-    '#title' => '#multiple, #required, no #default_value',
-    '#required' => TRUE,
-    '#multiple' => TRUE,
-  );
-
-  $form['submit'] = array('#type' => 'submit', '#value' => 'Submit');
-  return $form;
-}
-
-/**
- * Builds a form to test select elements when #options is not an array.
- *
- * @deprecated Use \Drupal\form_test\testEmptySelect()
- */
-function form_test_empty_select($form, &$form_state) {
-  $form['empty_select'] = array(
-    '#type' => 'select',
-    '#title' => t('Empty Select'),
-    '#multiple' => FALSE,
-    '#options' => NULL,
-  );
-  return $form;
-}
-
-/**
- * Builds a form to test the language select form element.
- *
- * @deprecated Use \Drupal\form_test\testLanguageSelect()
- */
-function form_test_language_select() {
-  $form['#submit'] = array('_form_test_submit_values_json');
-
-  $form['languages_all'] = array(
-    '#title' => t('Languages: All'),
-    '#type' => 'language_select',
-    '#languages' => LanguageInterface::STATE_ALL,
-    '#default_value' => 'xx',
-  );
-  $form['languages_configurable'] = array(
-    '#title' => t('Languages: Configurable'),
-    '#type' => 'language_select',
-    '#languages' => LanguageInterface::STATE_CONFIGURABLE,
-    '#default_value' => 'en',
-  );
-  $form['languages_locked'] = array(
-    '#title' => t('Languages: Locked'),
-    '#type' => 'language_select',
-    '#languages' => LanguageInterface::STATE_LOCKED,
-  );
-  $form['languages_config_and_locked'] = array(
-    '#title' => t('Languages: Configurable and locked'),
-    '#type' => 'language_select',
-    '#languages' => LanguageInterface::STATE_CONFIGURABLE | LanguageInterface::STATE_LOCKED,
-    '#default_value' => 'dummy_value',
-  );
-  $form['language_custom_options'] = array(
-    '#title' => t('Languages: Custom'),
-    '#type' => 'language_select',
-    '#languages' => LanguageInterface::STATE_CONFIGURABLE | LanguageInterface::STATE_LOCKED,
-    '#options' => array('opt1' => 'First option', 'opt2' => 'Second option', 'opt3' => 'Third option'),
-    '#default_value' => 'opt2',
-  );
-
-  $form['submit'] = array('#type' => 'submit', '#value' => 'Submit');
-  return $form;
-}
-
-/**
  * Builds a form to test #type 'number' and 'range' validation.
  *
  * @param $element
@@ -925,55 +364,6 @@ function form_test_number($form, &$form_state, $element = 'number') {
 }
 
 /**
- * Form constructor for testing #type 'range' elements.
- *
- * @see form_test_range_submit()
- *
- * @deprecated Use \Drupal\form_test\testRange()
- */
-function form_test_range($form, &$form_state) {
-  $form['#submit'] = array('_form_test_submit_values_json');
-
-  $form['with_default_value'] = array(
-    '#type' => 'range',
-    '#title' => 'Range with default value',
-    '#min' => 10,
-    '#max' => 20,
-    '#step' => 2,
-    '#default_value' => 18,
-    '#description' => 'The default value is 18.',
-  );
-  $form['float'] = array(
-    '#type' => 'range',
-    '#title' => 'Float',
-    '#min' => 10,
-    '#max' => 11,
-    '#step' => 'any',
-    '#description' => 'Floating point number between 10 and 11.',
-  );
-  $form['integer'] = array(
-    '#type' => 'range',
-    '#title' => 'Integer',
-    '#min' => 2,
-    '#max' => 8,
-    '#step' => 2,
-    '#description' => 'Even integer between 2 and 8.',
-  );
-  $form['offset'] = array(
-    '#type' => 'range',
-    '#title' => 'Offset',
-    '#min' => 2.9,
-    '#max' => 10.9,
-    '#description' => 'Value between 2.9 and 10.9.',
-  );
-  $form['submit'] = array(
-    '#type' => 'submit',
-    '#value' => 'Submit',
-  );
-  return $form;
-}
-
-/**
  * Form constructor for testing invalid #type 'range' elements.
  *
  * @deprecated Use \Drupal\form_test\testRangeInvalid()
diff --git a/core/modules/system/tests/modules/form_test/form_test.routing.yml b/core/modules/system/tests/modules/form_test/form_test.routing.yml
index 56bd2d5..015cb97 100644
--- a/core/modules/system/tests/modules/form_test/form_test.routing.yml
+++ b/core/modules/system/tests/modules/form_test/form_test.routing.yml
@@ -71,7 +71,7 @@ form_test.autocomplete_2:
 form_test.alter_form:
   path: '/form-test/alter'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::alterForm'
+    _form: '\Drupal\form_test\Form\FormTestAlterForm'
     _title: 'Form altering test'
   requirements:
     _access: 'TRUE'
@@ -79,7 +79,7 @@ form_test.alter_form:
 form_test.validate_form:
   path: '/form-test/validate'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::validateForm'
+    _form: '\Drupal\form_test\Form\FormTestValidateForm'
     _title: 'Form validation handlers test'
   requirements:
     _access: 'TRUE'
@@ -87,7 +87,7 @@ form_test.validate_form:
 form_test.validate_required:
   path: '/form-test/validate-required'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::validateRequiredForm'
+    _form: '\Drupal\form_test\Form\FormTestValidateRequiredForm'
     _title: 'Form #required validation'
   requirements:
     _access: 'TRUE'
@@ -95,7 +95,7 @@ form_test.validate_required:
 form_test.validate_required_no_title:
   path: '/form-test/validate-required-no-title'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::validateRequiredFormNoTitle'
+    _form: '\Drupal\form_test\Form\FormTestValidateRequiredNoTitleForm'
     _title: 'Form #required validation without #title'
   requirements:
     _access: 'TRUE'
@@ -103,7 +103,7 @@ form_test.validate_required_no_title:
 form_test.validate_with_error_suppresion:
   path: '/form-test/limit-validation-errors'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::validateFormWithErrorSuppression'
+    _form: '\Drupal\form_test\Form\FormTestLimitValidationErrorsForm'
     _title: 'Form validation with some error suppression'
   requirements:
     _access: 'TRUE'
@@ -111,7 +111,7 @@ form_test.validate_with_error_suppresion:
 form_test.pattern:
   path: '/form-test/pattern'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::validatePattern'
+    _form: '\Drupal\form_test\Form\FormTestPatternForm'
     _title: 'Pattern validation'
   requirements:
     _access: 'TRUE'
@@ -167,7 +167,7 @@ form_test.vertical_tabs:
 form_test.storage:
   path: '/form_test/form-storage'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::testStorage'
+    _form: '\Drupal\form_test\Form\FormTestStorageForm'
     _title: 'Form storage test'
   requirements:
     _access: 'TRUE'
@@ -175,7 +175,7 @@ form_test.storage:
 form_test.state_clean:
   path: '/form_test/form-state-values-clean'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::testFormStateClean'
+    _form: '\Drupal\form_test\Form\FormTestFormStateValuesCleanForm'
     _title: 'Form state values clearance test'
   requirements:
     _access: 'TRUE'
@@ -183,7 +183,7 @@ form_test.state_clean:
 form_test.state_clean_advanced:
   path: '/form_test/form-state-values-clean-advanced'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::testFormStateCleanAdvanced'
+    _form: '\Drupal\form_test\Form\FormTestFormStateValuesCleanAdvancedForm'
     _title: 'Form state values clearance advanced test'
   requirements:
     _access: 'TRUE'
@@ -199,7 +199,7 @@ form_test.checkbox:
 form_test.select:
   path: '/form-test/select'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::testSelect'
+    _form: '\Drupal\form_test\Form\FormTestSelectForm'
     _title: 'Select'
   requirements:
     _access: 'TRUE'
@@ -207,7 +207,7 @@ form_test.select:
 form_test.empty_select:
   path: '/form-test/empty-select'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::testEmptySelect'
+    _form: '\Drupal\form_test\Form\FormTestEmptySelectForm'
     _title: 'Empty Select Element'
   requirements:
     _access: 'TRUE'
@@ -215,7 +215,7 @@ form_test.empty_select:
 form_test.language_select:
   path: '/form-test/language_select'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::testLanguageSelect'
+    _form: '\Drupal\form_test\Form\FormTestLanguageSelectForm'
     _title: 'Language Select'
   requirements:
     _access: 'TRUE'
@@ -247,7 +247,7 @@ form_test.number_range:
 form_test.range:
   path: '/form-test/range'
   defaults:
-    _content: '\Drupal\form_test\Form\FormTestForm::testRange'
+    _form: '\Drupal\form_test\Form\FormTestRangeForm'
     _title: 'Range'
   requirements:
     _access: 'TRUE'
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestAlterForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestAlterForm.php
new file mode 100644
index 0000000..3052d76
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestAlterForm.php
@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestAlterForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+
+/**
+ * Form builder for testing hook_form_alter() and hook_form_FORM_ID_alter().
+ */
+class FormTestAlterForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_alter_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    // Elements can be added as needed for future testing needs, but for now,
+    // we're only testing alter hooks that do not require any elements added by
+    // this function.
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestEmptySelectForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestEmptySelectForm.php
new file mode 100644
index 0000000..1434370
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestEmptySelectForm.php
@@ -0,0 +1,43 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestEmptySelectForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+
+/**
+ * Builds a form to test select elements when #options is not an array.
+ */
+class FormTestEmptySelectForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_empty_select';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $form['empty_select'] = array(
+      '#type' => 'select',
+      '#title' => t('Empty Select'),
+      '#multiple' => FALSE,
+      '#options' => NULL,
+    );
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestForm.php
index c777732..7481792 100644
--- a/core/modules/system/tests/modules/form_test/src/Form/FormTestForm.php
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestForm.php
@@ -13,114 +13,6 @@
 class FormTestForm {
 
   /**
-   * Wraps form_test_alter_form().
-   *
-   * @todo Remove form_test_alter_form().
-   */
-  public function alterForm() {
-    return \Drupal::formBuilder()->getForm('form_test_alter_form');
-  }
-
-  /**
-   * Wraps form_test_validate_form().
-   *
-   * @todo Remove form_test_validate_form().
-   */
-  public function validateForm() {
-    return \Drupal::formBuilder()->getForm('form_test_validate_form');
-  }
-
-  /**
-   * Wraps form_test_validate_required_form().
-   *
-   * @todo Remove form_test_validate_required_form().
-   */
-  public function validateRequiredForm() {
-    return \Drupal::formBuilder()->getForm('form_test_validate_required_form');
-  }
-
-  /**
-   * Wraps form_test_validate_required_form_no_title().
-   *
-   * @todo Remove form_test_validate_required_form_no_title().
-   */
-  public function validateRequiredFormNoTitle() {
-    return \Drupal::formBuilder()->getForm('form_test_validate_required_form_no_title');
-  }
-
-  /**
-   * Wraps form_test_limit_validation_errors_form().
-   *
-   * @todo Remove form_test_limit_validation_errors_form().
-   */
-  public function validateFormWithErrorSuppression() {
-    return \Drupal::formBuilder()->getForm('form_test_limit_validation_errors_form');
-  }
-
-  /**
-   * Wraps form_test_pattern_form().
-   *
-   * @todo Remove form_test_pattern_form().
-   */
-  public function validatePattern() {
-    return \Drupal::formBuilder()->getForm('form_test_pattern_form');
-  }
-
-  /**
-   * Wraps form_test_storage_form().
-   *
-   * @todo Remove form_test_storage_form().
-   */
-  public function testStorage() {
-    return \Drupal::formBuilder()->getForm('form_test_storage_form');
-  }
-
-  /**
-   * Wraps form_test_form_state_values_clean_form().
-   *
-   * @todo Remove form_test_form_state_values_clean_form().
-   */
-  public function testFormStateClean() {
-    return \Drupal::formBuilder()->getForm('form_test_form_state_values_clean_form');
-  }
-
-  /**
-   * Wraps form_test_form_state_values_clean_advanced_form().
-   *
-   * @todo Remove form_test_form_state_values_clean_advanced_form().
-   */
-  public function testFormStateCleanAdvanced() {
-    return \Drupal::formBuilder()->getForm('form_test_form_state_values_clean_advanced_form');
-  }
-
-  /**
-   * Wraps form_test_select().
-   *
-   * @todo Remove form_test_select().
-   */
-  public function testSelect() {
-    return \Drupal::formBuilder()->getForm('form_test_select');
-  }
-
-  /**
-   * Wraps form_test_empty_select().
-   *
-   * @todo Remove form_test_empty_select().
-   */
-  public function testEmptySelect() {
-    return \Drupal::formBuilder()->getForm('form_test_empty_select');
-  }
-
-  /**
-   * Wraps form_test_language_select().
-   *
-   * @todo Remove form_test_language_select().
-   */
-  public function testLanguageSelect() {
-    return \Drupal::formBuilder()->getForm('form_test_language_select');
-  }
-
-  /**
    * Wraps form_test_placeholder_test().
    *
    * @todo Remove form_test_placeholder_test().
@@ -148,15 +40,6 @@ public function testNumberRange() {
   }
 
   /**
-   * Wraps form_test_range().
-   *
-   * @todo Remove form_test_range().
-   */
-  public function testRange() {
-    return \Drupal::formBuilder()->getForm('form_test_range');
-  }
-
-  /**
    * Wraps form_test_range_invalid().
    *
    * @todo Remove form_test_range_invalid().
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestFormStateValuesCleanAdvancedForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestFormStateValuesCleanAdvancedForm.php
new file mode 100644
index 0000000..879d7b3
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestFormStateValuesCleanAdvancedForm.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestFormStateValuesCleanAdvancedForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+
+/**
+ * Form builder for form_state_values_clean() test.
+ */
+class FormTestFormStateValuesCleanAdvancedForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_form_state_values_clean_advanced_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    // Build an example form containing a managed file and a submit form element.
+    $form['image'] = array(
+      '#type' => 'managed_file',
+      '#title' => t('Image'),
+      '#upload_location' => 'public://',
+      '#default_value' => 0,
+    );
+    $form['submit'] = array(
+      '#type' => 'submit',
+      '#value' => t('Submit'),
+    );
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    form_state_values_clean($form_state);
+    print t('You WIN!');
+    exit;
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestFormStateValuesCleanForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestFormStateValuesCleanForm.php
new file mode 100644
index 0000000..5c258d4
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestFormStateValuesCleanForm.php
@@ -0,0 +1,52 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestFormStateValuesCleanForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Component\Serialization\Json;
+use Drupal\Core\Form\FormBase;
+
+/**
+ * Form builder for form_state_values_clean() test.
+ */
+class FormTestFormStateValuesCleanForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_form_state_values_clean_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    // Build an example form containing multiple submit and button elements; not
+    // only on the top-level.
+    $form = array('#tree' => TRUE);
+    $form['foo'] = array('#type' => 'submit', '#value' => t('Submit'));
+    $form['bar'] = array('#type' => 'submit', '#value' => t('Submit'));
+    $form['beer'] = array('#type' => 'value', '#value' => 1000);
+    $form['baz']['foo'] = array('#type' => 'button', '#value' => t('Submit'));
+    $form['baz']['baz'] = array('#type' => 'submit', '#value' => t('Submit'));
+    $form['baz']['beer'] = array('#type' => 'value', '#value' => 2000);
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    form_state_values_clean($form_state);
+    // This won't have a proper JSON header, but Drupal doesn't check for that
+    // anyway so this is fine until it's replaced with a JsonResponse.
+    print Json::encode($form_state['values']);
+    exit;
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestLanguageSelectForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestLanguageSelectForm.php
new file mode 100644
index 0000000..711b369
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestLanguageSelectForm.php
@@ -0,0 +1,72 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestLanguageSelectForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Language\LanguageInterface;
+use Symfony\Component\HttpFoundation\JsonResponse;
+
+/**
+ * Builds a form to test the language select form element.
+ */
+class FormTestLanguageSelectForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_language_select';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $form['languages_all'] = array(
+      '#title' => t('Languages: All'),
+      '#type' => 'language_select',
+      '#languages' => LanguageInterface::STATE_ALL,
+      '#default_value' => 'xx',
+    );
+    $form['languages_configurable'] = array(
+      '#title' => t('Languages: Configurable'),
+      '#type' => 'language_select',
+      '#languages' => LanguageInterface::STATE_CONFIGURABLE,
+      '#default_value' => 'en',
+    );
+    $form['languages_locked'] = array(
+      '#title' => t('Languages: Locked'),
+      '#type' => 'language_select',
+      '#languages' => LanguageInterface::STATE_LOCKED,
+    );
+    $form['languages_config_and_locked'] = array(
+      '#title' => t('Languages: Configurable and locked'),
+      '#type' => 'language_select',
+      '#languages' => LanguageInterface::STATE_CONFIGURABLE | LanguageInterface::STATE_LOCKED,
+      '#default_value' => 'dummy_value',
+    );
+    $form['language_custom_options'] = array(
+      '#title' => t('Languages: Custom'),
+      '#type' => 'language_select',
+      '#languages' => LanguageInterface::STATE_CONFIGURABLE | LanguageInterface::STATE_LOCKED,
+      '#options' => array('opt1' => 'First option', 'opt2' => 'Second option', 'opt3' => 'Third option'),
+      '#default_value' => 'opt2',
+    );
+
+    $form['submit'] = array('#type' => 'submit', '#value' => 'Submit');
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    $form_state['response'] = new JsonResponse($form_state['values']);
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestLimitValidationErrorsForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestLimitValidationErrorsForm.php
new file mode 100644
index 0000000..3838b5e
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestLimitValidationErrorsForm.php
@@ -0,0 +1,104 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestLimitValidationErrorsForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+
+/**
+ * Builds a simple form with a button triggering partial validation.
+ */
+class FormTestLimitValidationErrorsForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_limit_validation_errors_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $form['title'] = array(
+      '#type' => 'textfield',
+      '#title' => 'Title',
+      '#required' => TRUE,
+    );
+
+    $form['test'] = array(
+      '#title' => 'Test',
+      '#type' => 'textfield',
+      '#element_validate' => array('form_test_limit_validation_errors_element_validate_test'),
+    );
+    $form['test_numeric_index'] = array(
+      '#tree' => TRUE,
+    );
+    $form['test_numeric_index'][0] = array(
+      '#title' => 'Test (numeric index)',
+      '#type' => 'textfield',
+      '#element_validate' => array('form_test_limit_validation_errors_element_validate_test'),
+    );
+
+    $form['test_substring'] = array(
+      '#tree' => TRUE,
+    );
+    $form['test_substring']['foo'] = array(
+      '#title' => 'Test (substring) foo',
+      '#type' => 'textfield',
+      '#element_validate' => array('form_test_limit_validation_errors_element_validate_test'),
+    );
+    $form['test_substring']['foobar'] = array(
+      '#title' => 'Test (substring) foobar',
+      '#type' => 'textfield',
+      '#element_validate' => array('form_test_limit_validation_errors_element_validate_test'),
+    );
+
+    $form['actions']['partial'] = array(
+      '#type' => 'submit',
+      '#limit_validation_errors' => array(array('test')),
+      '#submit' => array(array($this, 'partialSubmitForm')),
+      '#value' => t('Partial validate'),
+    );
+    $form['actions']['partial_numeric_index'] = array(
+      '#type' => 'submit',
+      '#limit_validation_errors' => array(array('test_numeric_index', 0)),
+      '#submit' => array(array($this, 'partialSubmitForm')),
+      '#value' => t('Partial validate (numeric index)'),
+    );
+    $form['actions']['substring'] = array(
+      '#type' => 'submit',
+      '#limit_validation_errors' => array(array('test_substring', 'foo')),
+      '#submit' => array(array($this, 'partialSubmitForm')),
+      '#value' => t('Partial validate (substring)'),
+    );
+    $form['actions']['full'] = array(
+      '#type' => 'submit',
+      '#value' => t('Full validate'),
+    );
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function partialSubmitForm(array &$form, array &$form_state) {
+    // The title has not been validated, thus its value - in case of the test case
+    // an empty string - may not be set.
+    if (!isset($form_state['values']['title']) && isset($form_state['values']['test'])) {
+      drupal_set_message('Only validated values appear in the form values.');
+    }
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestPatternForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestPatternForm.php
new file mode 100644
index 0000000..7df5f7a
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestPatternForm.php
@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestPatternForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+
+/**
+ * Builds a simple form using the FAPI #pattern proterty.
+ */
+class FormTestPatternForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_pattern_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $form['textfield'] = array(
+      '#type' => 'textfield',
+      '#title' => 'One digit followed by lowercase letters',
+      '#pattern' => '[0-9][a-z]+',
+    );
+    $form['tel'] = array(
+      '#type' => 'tel',
+      '#title' => 'Everything except numbers',
+      '#pattern' => '[^\d]*',
+    );
+    $form['password'] = array(
+      '#type' => 'password',
+      '#title' => 'Password',
+      '#pattern' => '[01]+',
+    );
+    $form['url'] = array(
+      '#type' => 'url',
+      '#title' => 'Client side validation',
+      '#decription' => 'Just client side validation, using the #pattern attribute.',
+      '#attributes' => array(
+        'pattern' => '.*foo.*',
+      ),
+      '#pattern' => 'ignored',
+    );
+    $form['submit'] = array(
+      '#type' => 'submit',
+      '#value' => 'Submit',
+    );
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestRangeForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestRangeForm.php
new file mode 100644
index 0000000..fff5126
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestRangeForm.php
@@ -0,0 +1,75 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestRangeForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Symfony\Component\HttpFoundation\JsonResponse;
+
+/**
+ * Form constructor for testing #type 'range' elements.
+ */
+class FormTestRangeForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_range';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $form['with_default_value'] = array(
+      '#type' => 'range',
+      '#title' => 'Range with default value',
+      '#min' => 10,
+      '#max' => 20,
+      '#step' => 2,
+      '#default_value' => 18,
+      '#description' => 'The default value is 18.',
+    );
+    $form['float'] = array(
+      '#type' => 'range',
+      '#title' => 'Float',
+      '#min' => 10,
+      '#max' => 11,
+      '#step' => 'any',
+      '#description' => 'Floating point number between 10 and 11.',
+    );
+    $form['integer'] = array(
+      '#type' => 'range',
+      '#title' => 'Integer',
+      '#min' => 2,
+      '#max' => 8,
+      '#step' => 2,
+      '#description' => 'Even integer between 2 and 8.',
+    );
+    $form['offset'] = array(
+      '#type' => 'range',
+      '#title' => 'Offset',
+      '#min' => 2.9,
+      '#max' => 10.9,
+      '#description' => 'Value between 2.9 and 10.9.',
+    );
+    $form['submit'] = array(
+      '#type' => 'submit',
+      '#value' => 'Submit',
+    );
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    $form_state['response'] = new JsonResponse($form_state['values']);
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestSelectForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestSelectForm.php
new file mode 100644
index 0000000..5227ae4
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestSelectForm.php
@@ -0,0 +1,133 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestSelectForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Symfony\Component\HttpFoundation\JsonResponse;
+
+/**
+ * Builds a form to test #type 'select' validation.
+ */
+class FormTestSelectForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_select';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $base = array(
+      '#type' => 'select',
+      '#options' => array('one' => 'one', 'two' => 'two', 'three' => 'three'),
+    );
+
+    $form['select'] = $base + array(
+      '#title' => '#default_value one',
+      '#default_value' => 'one',
+    );
+    $form['select_required'] = $base + array(
+      '#title' => '#default_value one, #required',
+      '#required' => TRUE,
+      '#default_value' => 'one',
+    );
+    $form['select_optional'] = $base + array(
+      '#title' => '#default_value one, not #required',
+      '#required' => FALSE,
+      '#default_value' => 'one',
+    );
+    $form['empty_value'] = $base + array(
+      '#title' => '#default_value one, #required, #empty_value 0',
+      '#required' => TRUE,
+      '#default_value' => 'one',
+      '#empty_value' => 0,
+    );
+    $form['empty_value_one'] = $base + array(
+      '#title' => '#default_value = #empty_value, #required',
+      '#required' => TRUE,
+      '#default_value' => 'one',
+      '#empty_value' => 'one',
+    );
+
+    $form['no_default'] = $base + array(
+      '#title' => 'No #default_value, #required',
+      '#required' => TRUE,
+    );
+    $form['no_default_optional'] = $base + array(
+      '#title' => 'No #default_value, not #required',
+      '#required' => FALSE,
+      '#description' => 'Should result in "one" because it is not required and there is no #empty_value requested, so default browser behavior of preselecting first option is in effect.',
+    );
+    $form['no_default_optional_empty_value'] = $base + array(
+      '#title' => 'No #default_value, not #required, #empty_value empty string',
+      '#empty_value' => '',
+      '#required' => FALSE,
+      '#description' => 'Should result in an empty string (due to #empty_value) because it is optional.',
+    );
+
+    $form['no_default_empty_option'] = $base + array(
+      '#title' => 'No #default_value, #required, #empty_option',
+      '#required' => TRUE,
+      '#empty_option' => '- Choose -',
+    );
+    $form['no_default_empty_option_optional'] = $base + array(
+      '#title' => 'No #default_value, not #required, #empty_option',
+      '#empty_option' => '- Dismiss -',
+      '#description' => 'Should result in an empty string (default of #empty_value) because it is optional.',
+    );
+
+    $form['no_default_empty_value'] = $base + array(
+      '#title' => 'No #default_value, #required, #empty_value 0',
+      '#required' => TRUE,
+      '#empty_value' => 0,
+      '#description' => 'Should never result in 0.',
+    );
+    $form['no_default_empty_value_one'] = $base + array(
+      '#title' => 'No #default_value, #required, #empty_value one',
+      '#required' => TRUE,
+      '#empty_value' => 'one',
+      '#description' => 'A mistakenly assigned #empty_value contained in #options should not be valid.',
+    );
+    $form['no_default_empty_value_optional'] = $base + array(
+      '#title' => 'No #default_value, not #required, #empty_value 0',
+      '#required' => FALSE,
+      '#empty_value' => 0,
+      '#description' => 'Should result in 0 because it is optional.',
+    );
+
+    $form['multiple'] = $base + array(
+      '#title' => '#multiple, #default_value two',
+      '#default_value' => array('two'),
+      '#multiple' => TRUE,
+    );
+    $form['multiple_no_default'] = $base + array(
+      '#title' => '#multiple, no #default_value',
+      '#multiple' => TRUE,
+    );
+    $form['multiple_no_default_required'] = $base + array(
+      '#title' => '#multiple, #required, no #default_value',
+      '#required' => TRUE,
+      '#multiple' => TRUE,
+    );
+
+    $form['submit'] = array('#type' => 'submit', '#value' => 'Submit');
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    $form_state['response'] = new JsonResponse($form_state['values']);
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestStorageForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestStorageForm.php
new file mode 100644
index 0000000..9106013
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestStorageForm.php
@@ -0,0 +1,102 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestStorageForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Component\Utility\String;
+use Drupal\Core\Form\FormBase;
+
+/**
+ * A multistep form for testing the form storage.
+ *
+ * It uses two steps for editing a virtual "thing". Any changes to it are saved
+ * in the form storage and have to be present during any step. By setting the
+ * request parameter "cache" the form can be tested with caching enabled, as
+ * it would be the case, if the form would contain some #ajax callbacks.
+ */
+class FormTestStorageForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_storage_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    if ($form_state['rebuild']) {
+      $form_state['input'] = array();
+    }
+    // Initialize
+    if (empty($form_state['storage'])) {
+      if (empty($form_state['input'])) {
+        $_SESSION['constructions'] = 0;
+      }
+      // Put the initial thing into the storage
+      $form_state['storage'] = array(
+        'thing' => array(
+          'title' => 'none',
+          'value' => '',
+        ),
+      );
+    }
+    // Count how often the form is constructed.
+    $_SESSION['constructions']++;
+    drupal_set_message("Form constructions: " . $_SESSION['constructions']);
+
+    $form['title'] = array(
+      '#type' => 'textfield',
+      '#title' => 'Title',
+      '#default_value' => $form_state['storage']['thing']['title'],
+      '#required' => TRUE,
+    );
+    $form['value'] = array(
+      '#type' => 'textfield',
+      '#title' => 'Value',
+      '#default_value' => $form_state['storage']['thing']['value'],
+      '#element_validate' => array('form_test_storage_element_validate_value_cached'),
+    );
+    $form['continue_button'] = array(
+      '#type' => 'button',
+      '#value' => 'Reset',
+      // Rebuilds the form without keeping the values.
+    );
+    $form['continue_submit'] = array(
+      '#type' => 'submit',
+      '#value' => 'Continue submit',
+      '#submit' => array('form_storage_test_form_continue_submit'),
+    );
+    $form['submit'] = array(
+      '#type' => 'submit',
+      '#value' => 'Save',
+    );
+
+    if (\Drupal::request()->get('cache')) {
+      // Manually activate caching, so we can test that the storage keeps working
+      // when it's enabled.
+      $form_state['cache'] = TRUE;
+    }
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    drupal_set_message("Title: " . String::checkPlain($form_state['values']['title']));
+    drupal_set_message("Form constructions: " . $_SESSION['constructions']);
+    if (isset($form_state['storage']['thing']['changed'])) {
+      drupal_set_message("The thing has been changed.");
+    }
+    $form_state['redirect_route']['route_name'] = '<front>';
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestValidateForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestValidateForm.php
new file mode 100644
index 0000000..50cf98f
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestValidateForm.php
@@ -0,0 +1,81 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestValidateForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\form_test\Callbacks;
+
+/**
+ * Form builder for testing drupal_validate_form().
+ *
+ * Serves for testing form processing and alterations by form validation
+ * handlers, especially for the case of a validation error:
+ * - form_set_value() should be able to alter submitted values in
+ *   $form_state['values'] without affecting the form element.
+ * - #element_validate handlers should be able to alter the $element in the form
+ *   structure and the alterations should be contained in the rebuilt form.
+ * - #validate handlers should be able to alter the $form and the alterations
+ *   should be contained in the rebuilt form.
+ */
+class FormTestValidateForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_validate_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $object = new Callbacks();
+
+    $form['name'] = array(
+      '#type' => 'textfield',
+      '#title' => 'Name',
+      '#default_value' => '',
+      '#element_validate' => array(array($object, 'validateName')),
+    );
+    $form['submit'] = array(
+      '#type' => 'submit',
+      '#value' => 'Save',
+    );
+
+    // To simplify this test, enable form caching and use form storage to
+    // remember our alteration.
+    $form_state['cache'] = TRUE;
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, array &$form_state) {
+    if ($form_state['values']['name'] == 'validate') {
+      // Alter the form element.
+      $form['name']['#value'] = '#value changed by #validate';
+      // Alter the submitted value in $form_state.
+      form_set_value($form['name'], 'value changed by form_set_value() in #validate', $form_state);
+      // Output the element's value from $form_state.
+      drupal_set_message(t('@label value: @value', array('@label' => $form['name']['#title'], '@value' => $form_state['values']['name'])));
+
+      // Trigger a form validation error to see our changes.
+      form_set_error('', $form_state);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestValidateRequiredForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestValidateRequiredForm.php
new file mode 100644
index 0000000..e25d18f
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestValidateRequiredForm.php
@@ -0,0 +1,82 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestValidateRequiredForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+
+/**
+ * Form constructor to test the #required property.
+ */
+class FormTestValidateRequiredForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_validate_required_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $options = array('foo' => 'foo', 'bar' => 'bar');
+    $validate = array('form_test_validate_required_form_element_validate');
+
+    $form['textfield'] = array(
+      '#type' => 'textfield',
+      '#title' => 'Name',
+      '#required' => TRUE,
+      '#required_error' => t('Please enter a name.'),
+    );
+    $form['checkboxes'] = array(
+      '#type' => 'checkboxes',
+      '#title' => 'Checkboxes',
+      '#options' => $options,
+      '#required' => TRUE,
+      '#form_test_required_error' => t('Please choose at least one option.'),
+      '#element_validate' => $validate,
+    );
+    $form['select'] = array(
+      '#type' => 'select',
+      '#title' => 'Select',
+      '#options' => $options,
+      '#required' => TRUE,
+      '#form_test_required_error' => t('Please select something.'),
+      '#element_validate' => $validate,
+    );
+    $form['radios'] = array(
+      '#type' => 'radios',
+      '#title' => 'Radios',
+      '#options' => $options,
+      '#required' => TRUE,
+    );
+    $form['radios_optional'] = array(
+      '#type' => 'radios',
+      '#title' => 'Radios (optional)',
+      '#options' => $options,
+    );
+    $form['radios_optional_default_value_false'] = array(
+      '#type' => 'radios',
+      '#title' => 'Radios (optional, with a default value of FALSE)',
+      '#options' => $options,
+      '#default_value' => FALSE,
+    );
+    $form['actions'] = array('#type' => 'actions');
+    $form['actions']['submit'] = array('#type' => 'submit', '#value' => 'Submit');
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    drupal_set_message('The form_test_validate_required_form form was submitted successfully.');
+  }
+
+}
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestValidateRequiredNoTitleForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestValidateRequiredNoTitleForm.php
new file mode 100644
index 0000000..25e5076
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestValidateRequiredNoTitleForm.php
@@ -0,0 +1,44 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\Form\FormTestValidateRequiredNoTitleForm.
+ */
+
+namespace Drupal\form_test\Form;
+
+use Drupal\Core\Form\FormBase;
+
+/**
+ * Form constructor to test the #required property without #title.
+ */
+class FormTestValidateRequiredNoTitleForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_validate_required_form_no_title';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $form['textfield'] = array(
+      '#type' => 'textfield',
+      '#required' => TRUE,
+    );
+    $form['actions'] = array('#type' => 'actions');
+    $form['actions']['submit'] = array('#type' => 'submit', '#value' => 'Submit');
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    drupal_set_message('The form_test_validate_required_form_no_title form was submitted successfully.');
+  }
+
+}