Honour discount conditions in BuyXGetY

packages/core/src/DiscountTypes/BuyXGetY.php

@@ -51,6 +51,10 @@ public function getRewardQuantity($linesQuantity, $minQty, $rewardQty, $maxRewar
      */
     public function apply(CartContract $cart): CartContract
     {
+        if (! $this->checkDiscountConditions($cart)) {
+            return $cart;
+        }
+
         $data = $this->discount->data;
 
         $minQty = $data['min_qty'] ?? null;

tests/core/Unit/DiscountTypes/BuyXGetYConditionsTest.php

@@ -0,0 +1,136 @@
+<?php
+
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Lunar\DiscountTypes\BuyXGetY;
+use Lunar\Models\Cart;
+use Lunar\Models\Channel;
+use Lunar\Models\Currency;
+use Lunar\Models\Customer;
+use Lunar\Models\CustomerGroup;
+use Lunar\Models\Discount;
+use Lunar\Models\Price;
+use Lunar\Models\Product;
+use Lunar\Models\ProductVariant;
+use Lunar\Tests\Core\TestCase;
+
+uses(TestCase::class);
+
+uses(RefreshDatabase::class);
+
+/**
+ * `AmountOff::apply()` guards on `checkDiscountConditions()`; `BuyXGetY::apply()`
+ * does not, so it applies whenever the quantity condition is met.
+ *
+ * Dates, `max_uses`, the coupon and the channel are already enforced by the
+ * query in `DiscountManager::getDiscounts()`, so those still hold. What is only
+ * checked in `checkDiscountConditions()` — the minimum spend, customer
+ * restrictions and `max_uses_per_user` — is ignored entirely.
+ */
+function buyXGetYConditionCart(array $discountData, array $discountAttributes = []): Cart
+{
+    $customerGroup = CustomerGroup::factory()->create(['default' => true]);
+    $channel = Channel::factory()->create(['default' => true]);
+    $currency = Currency::factory()->create(['code' => 'GBP', 'default' => true]);
+
+    $conditionProduct = Product::factory()->create();
+    $rewardProduct = Product::factory()->create();
+
+    $condition = ProductVariant::factory()->create(['product_id' => $conditionProduct->id]);
+    $reward = ProductVariant::factory()->create(['product_id' => $rewardProduct->id]);
+
+    foreach ([$condition, $reward] as $variant) {
+        Price::factory()->create([
+            'price' => 1000, // £10
+            'min_quantity' => 1,
+            'currency_id' => $currency->id,
+            'priceable_type' => $variant->getMorphClass(),
+            'priceable_id' => $variant->id,
+        ]);
+    }
+
+    $discount = Discount::factory()->create(array_merge([
+        'type' => BuyXGetY::class,
+        'name' => 'Buy one get one',
+        'starts_at' => now()->subDay(),
+        'data' => array_merge([
+            'min_qty' => 1,
+            'reward_qty' => 1,
+            'automatically_add_rewards' => false,
+        ], $discountData),
+    ], $discountAttributes));
+
+    $discount->channels()->attach([
+        $channel->id => ['enabled' => true, 'starts_at' => now()->subDay()],
+    ]);
+
+    $discount->customerGroups()->attach([
+        $customerGroup->id => ['enabled' => true, 'starts_at' => now()->subDay()],
+    ]);
+
+    $discount->discountables()->create([
+        'discountable_type' => $conditionProduct->getMorphClass(),
+        'discountable_id' => $conditionProduct->id,
+        'type' => 'condition',
+    ]);
+
+    $discount->discountables()->create([
+        'discountable_type' => $rewardProduct->getMorphClass(),
+        'discountable_id' => $rewardProduct->id,
+        'type' => 'reward',
+    ]);
+
+    $cart = Cart::factory()->create([
+        'channel_id' => $channel->id,
+        'currency_id' => $currency->id,
+        'coupon_code' => null,
+    ]);
+
+    // £10 of the condition product and £10 of the reward product: £20 total.
+    $cart->lines()->create([
+        'purchasable_type' => $condition->getMorphClass(),
+        'purchasable_id' => $condition->id,
+        'quantity' => 1,
+    ]);
+
+    $cart->lines()->create([
+        'purchasable_type' => $reward->getMorphClass(),
+        'purchasable_id' => $reward->id,
+        'quantity' => 1,
+    ]);
+
+    return $cart->refresh();
+}
+
+test('is not applied when the cart is below the minimum spend', function () {
+    // £50 minimum against a £20 cart.
+    $cart = buyXGetYConditionCart([
+        'min_prices' => ['GBP' => 5000],
+    ]);
+
+    $cart->calculate();
+
+    expect($cart->discountTotal->value)->toEqual(0);
+});
+
+test('is applied when the cart meets the minimum spend', function () {
+    // £10 minimum against a £20 cart.
+    $cart = buyXGetYConditionCart([
+        'min_prices' => ['GBP' => 1000],
+    ]);
+
+    $cart->calculate();
+
+    expect($cart->discountTotal->value)->toBeGreaterThan(0);
+});
+
+test('is not applied when the cart customer is not on the discount', function () {
+    $cart = buyXGetYConditionCart([]);
+
+    // Restrict the discount to a customer this cart does not belong to.
+    $discount = Discount::first();
+    $discount->customers()->attach(Customer::factory()->create()->id);
+
+    $cart->refresh()->calculate();
+
+    expect($cart->discountTotal->value)->toEqual(0);
+});