MDL-81915 admin: Fix test_admin_output_new_settings_by_page unit test

lib/tests/adminlib_test.php

@@ -128,33 +128,34 @@ public function test_db_should_replace_additional_skip_tables(string $table, str
     }
 
     /**
-     * Test method used by upgradesettings.php to make sure
-     * there are no missing settings in PHPUnit and Behat tests.
+     * Test admin_output_new_settings_by_page method.
      *
      * @covers ::admin_output_new_settings_by_page
      */
     public function test_admin_output_new_settings_by_page() {
         $this->resetAfterTest();
         $this->setAdminUser();
 
+        $root = admin_get_root(true, true);
+        // The initial list of html pages with no default settings.
+        $initialsettings = admin_output_new_settings_by_page($root);
+        $this->assertArrayHasKey('supportcontact', $initialsettings);
+        $this->assertArrayHasKey('frontpagesettings', $initialsettings);
+        // Existing default setting.
+        $this->assertArrayNotHasKey('modsettingbook', $initialsettings);
+
         // Add settings not set during PHPUnit init.
         set_config('supportemail', '[email protected]');
         $frontpage = new \admin_setting_special_frontpagedesc();
         $frontpage->write_setting('test test');
-
-        // NOTE: if this test fails then it is most likely extra setting in
-        // some additional plugin without default - developer needs to add
-        // a workaround into their db/install.php for PHPUnit and Behat.
-
-        $root = admin_get_root(true, true);
-        $new = admin_output_new_settings_by_page($root);
-        $this->assertSame([], $new);
-
+        // Remove a default setting.
         unset_config('numbering', 'book');
-        unset_config('supportemail');
+
         $root = admin_get_root(true, true);
         $new = admin_output_new_settings_by_page($root);
-        $this->assertCount(2, $new);
+        $this->assertArrayNotHasKey('supportcontact', $new);
+        $this->assertArrayNotHasKey('frontpagesettings', $new);
+        $this->assertArrayHasKey('modsettingbook', $new);
     }
 
     /**