React\Promise\PromiseTest\CancelTestTrait::cancelShouldHaveNoEffectIfCancellerDoesNothing PHP Method

    public function cancelShouldHaveNoEffectIfCancellerDoesNothing()
    {
        $adapter = $this->getPromiseTestAdapter(function () {
        });
        $adapter->promise()->then($this->expectCallableNever(), $this->expectCallableNever());
        $adapter->promise()->cancel();
        $adapter->promise()->cancel();
    }