--- /dev/null
+<?php
+
+namespace Drupal\session_test\Form;
+
+use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Form controller for the test config edit forms.
+ */
+class SessionTestForm extends FormBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getFormId() {
+ return 'session_test_form';
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function buildForm(array $form, FormStateInterface $form_state) {
+ $form['input'] = [
+ '#type' => 'textfield',
+ '#title' => 'Input',
+ '#required' => TRUE,
+ ];
+
+ $form['actions'] = ['#type' => 'actions'];
+ $form['actions']['submit'] = [
+ '#type' => 'submit',
+ '#value' => 'Save',
+ ];
+
+ return $form;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function submitForm(array &$form, FormStateInterface $form_state) {
+ drupal_set_message(SafeMarkup::format('Ok: @input', ['@input' => $form_state->getValue('input')]));
+ }
+
+}