Fixed #32204 -- Added quick filter to admin's navigation sidebar.

js_tests/admin/navigation.test.js

@@ -0,0 +1,24 @@
+/* global QUnit */
+'use strict';
+
+QUnit.module('admin.sidebar: filter', {
+    beforeEach: function() {
+        const $ = django.jQuery;
+        $('#qunit-fixture').append($('#nav-sidebar-filter').text());
+        this.navSidebar = $('#nav-sidebar');
+        this.navFilter = $('#nav-filter');
+        initSidebarQuickFilter();
+    }
+});
+
+QUnit.test('filter by a model name', function(assert) {
+    assert.equal(this.navSidebar.find('th[scope=row] a').length, 2);
+
+    this.navFilter.val('us'); // Matches 'users'.
+    this.navFilter[0].dispatchEvent(new Event('change'));
+    assert.equal(this.navSidebar.find('tr[class^="model-"]:visible').length, 1);
+
+    this.navFilter.val('nonexistent');
+    this.navFilter[0].dispatchEvent(new Event('change'));
+    assert.equal(this.navSidebar.find('tr[class^="model-"]:visible').length, 0);
+});