Merge pull request #279 from ciungulete/rounding_bug

Rounding bug with tax calculations

src/FirstPayment/Actions/AddGenericOrderItem.php

@@ -13,14 +13,16 @@ class AddGenericOrderItem extends BaseAction
      * @param \Illuminate\Database\Eloquent\Model $owner
      * @param \Money\Money $subtotal
      * @param string $description
+     * @param int $roundingMode
      */
-    public function __construct(Model $owner, Money $subtotal, string $description)
+    public function __construct(Model $owner, Money $subtotal, string $description, int $roundingMode = Money::ROUND_HALF_UP)
     {
         $this->owner = $owner;
         $this->taxPercentage = $this->owner->taxPercentage();
         $this->unitPrice = $subtotal;
         $this->currency = $subtotal->getCurrency()->getCode();
         $this->description = $description;
+        $this->roundingMode = $roundingMode;
     }
 
     /**

src/FirstPayment/Actions/BaseAction.php

@@ -4,6 +4,7 @@
 
 use Illuminate\Database\Eloquent\Model;
 use Laravel\Cashier\Cashier;
+use Money\Money;
 
 abstract class BaseAction
 {
@@ -25,6 +26,9 @@ abstract class BaseAction
     /** @var int */
     protected $quantity = 1;
 
+    /** @var int */
+    protected $roundingMode = Money::ROUND_HALF_UP;
+
     /**
      * Rebuild the Action from a payload.
      *
@@ -69,6 +73,14 @@ public function getCurrency()
         return $this->currency ?? strtoupper(Cashier::usesCurrency());
     }
 
+    /**
+     * @return int
+     */
+    public function getRoundingMode()
+    {
+        return $this->roundingMode;
+    }
+
     /**
      * @return float
      */
@@ -112,7 +124,7 @@ public function getTax()
     {
         return $this->getSubtotal()
                     ->multiply($this->getTaxPercentage())
-                    ->divide(100);
+                    ->divide(100, $this->getRoundingMode());
     }
 
     /**

src/SubscriptionBuilder/FirstPaymentSubscriptionBuilder.php

@@ -12,6 +12,7 @@
 use Laravel\Cashier\Plan\Contracts\PlanRepository;
 use Laravel\Cashier\Plan\Plan;
 use Laravel\Cashier\SubscriptionBuilder\Contracts\SubscriptionBuilder as Contract;
+use Money\Money;
 
 /**
  * Creates and configures a Mollie first payment to create a new mandate via Mollie's checkout
@@ -89,18 +90,20 @@ public function create()
         if ($this->isTrial) {
             $taxPercentage = $this->owner->taxPercentage() * 0.01;
             $total = $this->plan->firstPaymentAmount();
-
+          
             if ($total->isZero()) {
                 $vat = $total->subtract($total); // zero VAT
             } else {
-                $vat = $total->divide(1 + $taxPercentage)->multiply($taxPercentage);
+                $vat = $total->divide(1 + $taxPercentage)
+                             ->multiply($taxPercentage, $this->roundingMode($total, $taxPercentage));
             }
             $subtotal = $total->subtract($vat);
 
             $actions[] = new AddGenericOrderItem(
                 $this->owner,
                 $subtotal,
-                $this->plan->firstPaymentDescription()
+                $this->plan->firstPaymentDescription(),
+                $this->roundingMode($total, $taxPercentage)
             );
         } elseif ($coupon) {
             $actions[] = new ApplySubscriptionCouponToPayment($this->owner, $coupon, $actions->processedOrderItems());
@@ -240,4 +243,32 @@ protected function initializeFirstPaymentBuilder(Model $owner, $paymentOptions =
 
         return $this->firstPaymentBuilder;
     }
+
+    /**
+     * Format the money as basic decimal
+     *
+     * @param \Money\Money $total
+     * @param float $taxPercentage
+     *
+     * @return int
+     */
+    public function roundingMode(Money $total, float $taxPercentage)
+    {
+        $vat = $total->divide(1 + $taxPercentage)->multiply($taxPercentage);
+
+        $subtotal = $total->subtract($vat);
+
+        $recalculatedTax = $subtotal->multiply($taxPercentage * 100)->divide(100);
+
+        $finalTotal = $subtotal->add($recalculatedTax);
+
+        if ($finalTotal->equals($total)) {
+            return Money::ROUND_HALF_UP;
+        }
+        if ($finalTotal->greaterThan($total)) {
+            return Money::ROUND_UP;
+        }
+
+        return  Money::ROUND_DOWN;
+    }
 }

tests/SubscriptionBuilder/FirstPaymentSubscriptionBuilderApplyCorrectTaxTest.php

@@ -0,0 +1,117 @@
+<?php
+
+namespace Laravel\Cashier\Tests\SubscriptionBuilder;
+
+use Laravel\Cashier\Cashier;
+use Laravel\Cashier\Mollie\Contracts\CreateMolliePayment;
+use Laravel\Cashier\Mollie\Contracts\GetMollieCustomer;
+use Laravel\Cashier\SubscriptionBuilder\FirstPaymentSubscriptionBuilder;
+use Laravel\Cashier\Tests\BaseTestCase;
+use Mollie\Api\MollieApiClient;
+use Mollie\Api\Resources\Customer;
+use Mollie\Api\Resources\Payment;
+use Money\Money;
+
+class FirstPaymentSubscriptionBuilderApplyCorrectTaxTest extends BaseTestCase
+{
+    protected $user;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        Cashier::useCurrency('eur');
+        $this->withTestNow('2019-01-01');
+        $this->withPackageMigrations();
+        $this->withConfiguredPlans();
+        $this->user = $this->getCustomerUser(true, [
+            'tax_percentage' => 21,
+            'mollie_customer_id' => 'cst_unique_customer_id',
+        ]);
+    }
+
+    /** @test */
+    public function handlesTrialDaysAndFirstPaymentWithTaxAppliedCorrect()
+    {
+        $firstPaymentAmounts = collect(['10.00', '11.00', '21.00', '24.00', '280.00']);
+
+        $firstPaymentAmounts->each(function ($amount) {
+            $this->withMockedCreateMolliePayment();
+            $this->withMockedGetMollieCustomerTwice();
+
+            config(['cashier_plans.defaults.first_payment.amount.value' => $amount]);
+
+            $trialBuilder = $this->getBuilder();
+            $trialBuilder->trialDays(5)->create();
+            $this->assertEquals(
+                $amount,
+                $trialBuilder->getMandatePaymentBuilder()->getMolliePayload()['amount']['value']
+            );
+        });
+    }
+
+    /** @test */
+    public function roundingModeReturnCorrectValue()
+    {
+        $down = $this->getBuilder()->roundingMode(Money::EUR(1000), 0.21); //total is 1001
+        $equals = $this->getBuilder()->roundingMode(Money::EUR(1100), 0.21); // total is 1100
+        $up = $this->getBuilder()->roundingMode(Money::EUR(2100), 0.21); // total is 2099
+
+        $this->assertSame(Money::ROUND_UP, $down);
+        $this->assertSame(Money::ROUND_HALF_UP, $equals);
+        $this->assertSame(Money::ROUND_DOWN, $up);
+    }
+
+    /**
+     * @return \Laravel\Cashier\SubscriptionBuilder\FirstPaymentSubscriptionBuilder
+     */
+    protected function getBuilder()
+    {
+        return new FirstPaymentSubscriptionBuilder(
+            $this->user,
+            'default',
+            'monthly-10-1'
+        );
+    }
+
+    protected function withMockedGetMollieCustomer()
+    {
+        $this->mock(GetMollieCustomer::class, function ($mock) {
+            $customer = new Customer(new MollieApiClient);
+            $customer->id = 'cst_unique_customer_id';
+
+            return $mock->shouldReceive('execute')
+                ->with('cst_unique_customer_id')
+                ->once()
+                ->andReturn($customer);
+        });
+    }
+
+    protected function withMockedGetMollieCustomerTwice()
+    {
+        $this->mock(GetMollieCustomer::class, function ($mock) {
+            $customer = new Customer(new MollieApiClient);
+            $customer->id = 'cst_unique_customer_id';
+
+            return $mock->shouldReceive('execute')
+                ->with('cst_unique_customer_id')
+                ->twice()
+                ->andReturn($customer);
+        });
+    }
+
+    protected function withMockedCreateMolliePayment(): void
+    {
+        $this->mock(CreateMolliePayment::class, function ($mock) {
+            $payment = new Payment(new MollieApiClient);
+            $payment->id = 'tr_unique_payment_id';
+            $payment->_links = json_decode(json_encode([
+                'checkout' => [
+                    'href' => 'https://foo-redirect-bar.com',
+                    'type' => 'text/html',
+                ],
+            ]));
+
+            return $mock->shouldReceive('execute')->once()->andReturn($payment);
+        });
+    }
+}