public function testIsImmutable()
{
$arguments = [$arg0 = new \stdClass()];
$value = new FunctionCallValue('setUsername', $arguments);
// Mutate injected value
$arg0->foo = 'bar';
// Mutate returned value
$value->getArguments()[0]->foo = 'baz';
$this->assertEquals([new \stdClass()], $value->getArguments());
$this->assertEquals(['setUsername', [new \stdClass()]], $value->getValue());
}