diff --git a/tag/classes/tests/privacy_helper.php b/tag/classes/tests/privacy_helper.php
new file mode 100644
index 00000000000..b6351a715db
--- /dev/null
+++ b/tag/classes/tests/privacy_helper.php
@@ -0,0 +1,84 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Helpers for the core_tag subsystem implementation of privacy.
+ *
+ * @package    core_tag
+ * @copyright  2018 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_tag\tests;
+
+defined('MOODLE_INTERNAL') || die();
+
+use \core_privacy\tests\request\content_writer;
+
+global $CFG;
+
+/**
+ * Helpers for the core_tag subsystem implementation of privacy.
+ *
+ * @copyright  2018 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+trait privacy_helper {
+    /**
+     * Fetch all tags on a subcontext.
+     *
+     * @param   \context            $context    The context being stored.
+     * @param   array               $subcontext The subcontext path to check.
+     * @return  array
+     */
+    protected function get_tags_on_subcontext(\context $context, array $subcontext) {
+        $writer = \core_privacy\local\request\writer::with_context($context);
+        return $writer->get_related_data($subcontext, 'tags');
+    }
+
+    /**
+     * Check that all tags match on the specified context.
+     *
+     * @param   int                 $userid     The ID of the user being stored.
+     * @param   \context            $context    The context being stored.
+     * @param   array               $subcontext The subcontext path to check.
+     * @param   string              $component  The component being stored.
+     * @param   string              $itemtype    The tag area to store results for.
+     * @param   int                 $itemid     The itemid to store.
+     */
+    protected function assert_all_tags_match_on_context(
+        $userid,
+        \context $context,
+        array $subcontext,
+        $component,
+        $itemtype,
+        $itemid
+    ) {
+        $writer = \core_privacy\local\request\writer::with_context($context);
+
+        $dbtags = \core_tag_tag::get_item_tags($component, $itemtype, $itemid);
+        $exportedtags = $this->get_tags_on_subcontext($context, $subcontext);
+
+        $this->assertCount(count($dbtags), $exportedtags);
+
+        foreach ($dbtags as $tag) {
+            $this->assertTrue(isset($exportedtags[$tag->id]));
+            $this->assertEquals($exportedtags[$tag->id]->name, $tag->name);
+            $this->assertEquals($exportedtags[$tag->id]->rawname, $tag->rawname);
+            $this->assertEquals($exportedtags[$tag->id]->flag, $tag->flag);
+        }
+    }
+}