diff --git a/lib/tests/secondary_test.php b/lib/tests/secondary_test.php
new file mode 100644
index 00000000000..e54cfc37acd
--- /dev/null
+++ b/lib/tests/secondary_test.php
@@ -0,0 +1,133 @@
+<?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/>.
+
+use core\navigation\views\secondary;
+
+/**
+ * Class core_secondary_testcase
+ *
+ * Unit test for the secondary nav view.
+ *
+ * @package     core
+ * @category    navigation
+ * @copyright   2021 onwards Peter Dias
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class core_secondary_testcase extends advanced_testcase {
+    /**
+     * Test the get_leaf_nodes function
+     * @param float $siteorder The order for the siteadmin node
+     * @param float $courseorder The order for the course node
+     * @param float $moduleorder The order for the module node
+     * @dataProvider leaf_nodes_order_provider
+     */
+    public function test_get_leaf_nodes(float $siteorder, float $courseorder, float $moduleorder) {
+        global $PAGE;
+
+        // Create a secondary navigation and populate with some dummy nodes.
+        $secondary = new secondary($PAGE);
+        $secondary->add('Site Admin', '#', secondary::TYPE_SETTING, null, 'siteadmin');
+        $secondary->add('Course Admin', '#', secondary::TYPE_CUSTOM, null, 'courseadmin');
+        $secondary->add('Module Admin', '#', secondary::TYPE_SETTING, null, 'moduleadmin');
+        $nodes = [
+            navigation_node::TYPE_SETTING => [
+                'siteadmin' => $siteorder,
+                'moduleadmin' => $courseorder,
+            ],
+            navigation_node::TYPE_CUSTOM => [
+                'courseadmin' => $moduleorder,
+            ]
+        ];
+        $expectednodes = [
+            "$siteorder" => 'siteadmin',
+            "$courseorder" => 'moduleadmin',
+            "$moduleorder" => 'courseadmin',
+        ];
+
+        $method = new ReflectionMethod('core\navigation\views\secondary', 'get_leaf_nodes');
+        $method->setAccessible(true);
+        $sortednodes = $method->invoke($secondary, $secondary, $nodes);
+        foreach ($sortednodes as $order => $node) {
+            $this->assertEquals($expectednodes[$order], $node->key);
+        }
+    }
+
+    /**
+     * Data provider for test_get_leaf_nodes
+     * @return array
+     */
+    public function leaf_nodes_order_provider(): array {
+        return [
+            'Initialise the order with whole numbers' => [3, 2, 1],
+            'Initialise the order with a mix of whole and float numbers' => [2.1, 2, 1],
+        ];
+    }
+
+    /**
+     * Test the initialise in different contexts
+     *
+     * @param string $context The context to setup for - course, module, system
+     * @param string $expectedfirstnode The expected first node
+     * @dataProvider test_setting_initialise_provider
+     */
+    public function test_setting_initialise(string $context, string $expectedfirstnode) {
+        global $PAGE, $SITE;
+        $this->resetAfterTest();
+        $this->setAdminUser();
+        $pagecourse = $SITE;
+        $pageurl = '/';
+        switch ($context) {
+            case 'course':
+                $pagecourse = $this->getDataGenerator()->create_course();
+                $contextrecord = context_course::instance($pagecourse->id, MUST_EXIST);
+                $pageurl = new moodle_url('/course/view.php', ['id' => $pagecourse->id]);
+                break;
+            case 'module':
+                $pagecourse = $this->getDataGenerator()->create_course();
+                $assign = $this->getDataGenerator()->create_module('assign', ['course' => $pagecourse->id]);
+                $cm = get_coursemodule_from_id('assign', $assign->cmid);
+                $contextrecord = context_module::instance($cm->id);
+                $pageurl = new moodle_url('/mod/assign/view.php', ['id' => $cm->instance]);
+                $PAGE->set_cm($cm);
+                break;
+            case 'system':
+                $contextrecord = context_system::instance();
+                $PAGE->set_pagelayout('admin');
+                $pageurl = new moodle_url('/admin/index.php');
+
+        }
+        $PAGE->set_url($pageurl);
+        $PAGE->set_course($pagecourse);
+        $PAGE->set_context($contextrecord);
+
+        $node = new secondary($PAGE);
+        $node->initialise();
+        $children = $node->get_children_key_list();
+        $this->assertEquals($children[0], $expectedfirstnode);
+    }
+
+    /**
+     * Data provider for the test_setting_initialise function
+     * @return array
+     */
+    public function test_setting_initialise_provider(): array {
+        return [
+            'Testing in a course context' => ['course', 'coursehome'],
+            'Testing in a module context' => ['module', 'modulepage'],
+            'Testing in a site admin' => ['system', 'siteadminnode'],
+        ];
+    }
+}