Test user role weight change operation.
function testRoleWeightChange() {
$this
->drupalLogin($this->admin_user);
// Pick up a random role and get its weight.
$rid = array_rand(user_roles());
$role = user_role_load($rid);
$old_weight = $role->weight;
// Change the role weight and submit the form.
$edit = array(
'roles[' . $rid . '][weight]' => $old_weight + 1,
);
$this
->drupalPost('admin/people/permissions/roles', $edit, t('Save order'));
$this
->assertText(t('The role settings have been updated.'), 'The role settings form submitted successfully.');
// Retrieve the saved role and compare its weight.
$role = user_role_load($rid);
$new_weight = $role->weight;
$this
->assertTrue($old_weight + 1 == $new_weight, 'Role weight updated successfully.');
}