Fix privileges flaky test because the order in arrays matters for equality (#58790)

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

x-pack/test/api_integration/apis/security/privileges.ts

@@ -3,24 +3,20 @@
  * or more contributor license agreements. Licensed under the Elastic License;
  * you may not use this file except in compliance with the Elastic License.
  */
-
+import util from 'util';
+import { isEqual } from 'lodash';
 import { FtrProviderContext } from '../../ftr_provider_context';
 
 export default function({ getService }: FtrProviderContext) {
   const supertest = getService('supertest');
 
-  // FLAKY: https://github.com/elastic/kibana/issues/58785
+  describe('Privileges', () => {
-  describe.skip('Privileges', () => {
     describe('GET /api/security/privileges', () => {
       it('should return a privilege map with all known privileges, without actions', async () => {
-        await supertest
-          .get('/api/security/privileges')
-          .set('kbn-xsrf', 'xxx')
-          .send()
-          .expect(200, {
         // If you're adding a privilege to the following, that's great!
         // If you're removing a privilege, this breaks backwards compatibility
         // Roles are associated with these privileges, and we shouldn't be removing them in a minor version.
+        const expected = {
           features: {
             discover: ['all', 'read'],
             visualize: ['all', 'read'],
@@ -42,8 +38,36 @@ export default function({ getService }: FtrProviderContext) {
           },
           global: ['all', 'read'],
           space: ['all', 'read'],
-            reserved: ['monitoring', 'ml'],
+          reserved: ['ml', 'monitoring'],
+        };
+
+        await supertest
+          .get('/api/security/privileges')
+          .set('kbn-xsrf', 'xxx')
+          .send()
+          .expect(200)
+          .expect((res: any) => {
+            // when comparing privileges, the order of the privileges doesn't matter.
+            // supertest uses assert.deepStrictEqual.
+            // expect.js doesn't help us here.
+            // and lodash's isEqual doesn't know how to compare Sets.
+            const success = isEqual(res.body, expected, (value, other, key) => {
+              if (Array.isArray(value) && Array.isArray(other)) {
+                return isEqual(value.sort(), other.sort());
+              }
+
+              // Lodash types aren't correct, `undefined` should be supported as a return value here and it
+              // has special meaning.
+              return undefined as any;
             });
+
+            if (!success) {
+              throw new Error(
+                `Expected ${util.inspect(res.body)} to equal ${util.inspect(expected)}`
+              );
+            }
+          })
+          .expect(200);
       });
     });
   });