--- /dev/null
+<?php
+
+namespace Drupal\filter_test_plugin\Plugin\Filter;
+
+use Drupal\filter\FilterProcessResult;
+use Drupal\filter\Plugin\FilterBase;
+
+/**
+ * Provides a filter to limit allowed HTML tags.
+ *
+ * This filter does not do anything, but enabling of its module is done in a
+ * test.
+ *
+ * @see \Drupal\filter\Tests\FilterFormTest::testFilterForm()
+ *
+ * @Filter(
+ * id = "filter_sparkles",
+ * title = @Translation("Sparkles filter"),
+ * type = Drupal\filter\Plugin\FilterInterface::TYPE_HTML_RESTRICTOR,
+ * settings = {},
+ * weight = -10
+ * )
+ */
+class FilterSparkles extends FilterBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function process($text, $langcode) {
+ return new FilterProcessResult($text);
+ }
+
+}