public function testIsImmutable()
{
$id = 'Nelmio\\Entity\\User#user0#username';
$value = [$arg0 = new \stdClass()];
$definition = new UniqueValue($id, $value);
// Mutate injected value
$arg0->foo = 'bar';
// Mutate returned value
$definition->getValue()[0]->foo = 'baz';
$this->assertEquals([new \stdClass()], $definition->getValue());
}