--- /dev/null
+<?php
+
+namespace Drupal\field_test\Plugin\Field\FieldFormatter;
+
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Field\FormatterBase;
+
+/**
+ * Plugin implementation of the 'field_empty_test' formatter.
+ *
+ * @FieldFormatter(
+ * id = "field_empty_test",
+ * label = @Translation("Field empty test"),
+ * field_types = {
+ * "test_field",
+ * },
+ * weight = -5
+ * )
+ */
+class TestFieldEmptyFormatter extends FormatterBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function defaultSettings() {
+ return [
+ 'test_empty_string' => '**EMPTY FIELD**',
+ ] + parent::defaultSettings();
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function viewElements(FieldItemListInterface $items, $langcode) {
+ $elements = [];
+
+ if ($items->isEmpty()) {
+ // For fields with no value, just add the configured "empty" value.
+ $elements[0] = ['#markup' => $this->getSetting('test_empty_string')];
+ }
+ else {
+ foreach ($items as $delta => $item) {
+ // This formatter only needs to output raw for testing.
+ $elements[$delta] = ['#markup' => $item->value];
+ }
+ }
+
+ return $elements;
+ }
+
+}