--- /dev/null
+<?php
+
+namespace Drupal\FunctionalTests\Datetime;
+
+use Drupal\Core\Entity\Entity\EntityFormDisplay;
+use Drupal\Core\Entity\Entity\EntityViewDisplay;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Tests the functionality of TimestampAgoFormatter core field formatter.
+ *
+ * @group field
+ */
+class TimestampAgoFormatterTest extends BrowserTestBase {
+
+ /**
+ * An array of display options to pass to entity_get_display().
+ *
+ * @var array
+ */
+ protected $displayOptions;
+
+ /**
+ * A field storage to use in this test class.
+ *
+ * @var \Drupal\field\Entity\FieldStorageConfig
+ */
+ protected $fieldStorage;
+
+ /**
+ * The field used in this test class.
+ *
+ * @var \Drupal\field\Entity\FieldConfig
+ */
+ protected $field;
+
+ /**
+ * {@inheritdoc}
+ */
+ public static $modules = ['entity_test', 'field_ui'];
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function setUp() {
+ parent::setUp();
+
+ $web_user = $this->drupalCreateUser([
+ 'access administration pages',
+ 'view test entity',
+ 'administer entity_test content',
+ 'administer entity_test fields',
+ 'administer entity_test display',
+ 'administer entity_test form display',
+ 'view the administration theme',
+ ]);
+ $this->drupalLogin($web_user);
+
+ $field_name = 'field_timestamp';
+ $type = 'timestamp';
+ $widget_type = 'datetime_timestamp';
+ $formatter_type = 'timestamp_ago';
+
+ $this->fieldStorage = FieldStorageConfig::create([
+ 'field_name' => $field_name,
+ 'entity_type' => 'entity_test',
+ 'type' => $type,
+ ]);
+ $this->fieldStorage->save();
+ $this->field = FieldConfig::create([
+ 'field_storage' => $this->fieldStorage,
+ 'bundle' => 'entity_test',
+ 'required' => TRUE,
+ ]);
+ $this->field->save();
+
+ EntityFormDisplay::load('entity_test.entity_test.default')
+ ->setComponent($field_name, ['type' => $widget_type])
+ ->save();
+
+ $this->displayOptions = [
+ 'type' => $formatter_type,
+ 'label' => 'hidden',
+ ];
+
+ EntityViewDisplay::create([
+ 'targetEntityType' => $this->field->getTargetEntityTypeId(),
+ 'bundle' => $this->field->getTargetBundle(),
+ 'mode' => 'full',
+ 'status' => TRUE,
+ ])->setComponent($field_name, $this->displayOptions)
+ ->save();
+ }
+
+ /**
+ * Tests the formatter settings.
+ */
+ public function testSettings() {
+ $this->drupalGet('entity_test/structure/entity_test/display');
+
+ $edit = [
+ 'fields[field_timestamp][region]' => 'content',
+ 'fields[field_timestamp][type]' => 'timestamp_ago',
+ ];
+ $this->drupalPostForm(NULL, $edit, t('Save'));
+
+ $this->drupalPostForm(NULL, [], 'field_timestamp_settings_edit');
+ $edit = [
+ 'fields[field_timestamp][settings_edit_form][settings][future_format]' => 'ends in @interval',
+ 'fields[field_timestamp][settings_edit_form][settings][past_format]' => 'started @interval ago',
+ 'fields[field_timestamp][settings_edit_form][settings][granularity]' => 3,
+ ];
+ $this->drupalPostForm(NULL, $edit, 'Update');
+ $this->drupalPostForm(NULL, [], 'Save');
+
+ $this->assertSession()->pageTextContains('ends in 1 year 1 month 1 week');
+ $this->assertSession()->pageTextContains('started 1 year 1 month 1 week ago');
+ }
+
+}