Braintree\SubscriptionSearch::nextBillingDate PHP Method

    public static function nextBillingDate()
    {
        return new RangeNode('next_billing_date');
    }

 public function testSearch_nextBillingDate()
 {
     $creditCard = SubscriptionHelper::createCreditCard();
     $triallessPlan = SubscriptionHelper::triallessPlan();
     $trialPlan = SubscriptionHelper::trialPlan();
     $triallessSubscription = Braintree\Subscription::create(['paymentMethodToken' => $creditCard->token, 'planId' => $triallessPlan['id']])->subscription;
     $trialSubscription = Braintree\Subscription::create(['paymentMethodToken' => $creditCard->token, 'planId' => $trialPlan['id']])->subscription;
     $fiveDaysFromNow = new DateTime();
     $fiveDaysFromNow->modify("+5 days");
     $collection = Braintree\Subscription::search([Braintree\SubscriptionSearch::nextBillingDate()->greaterThanOrEqualTo($fiveDaysFromNow)]);
     $this->assertTrue(Test\Helper::includes($collection, $triallessSubscription));
     $this->assertFalse(Test\Helper::includes($collection, $trialSubscription));
 }