public function testCaseCancelledPromise_IsImmutable()
{
$deferred = $this->createDeferred();
$test = $this->getTest();
$mock = $test->createCallableMock();
$mock->expects($test->once())->method('__invoke')->with($test->identicalTo(1));
$deferred->cancel(1);
$deferred->cancel(2);
$deferred->getPromise()->then($test->expectCallableNever(), $test->expectCallableNever(), $mock);
}