fix: skip discounts with value 0€

src/Service/AccommodationBookingBreakdownCalculator.php

@@ -51,11 +51,14 @@ class AccommodationBookingBreakdownCalculator
         $discountSum = 0;
 
         foreach ($buckets as [$label, $percent, $base]) {
-            if (null === $percent) {
+            $amount = self::discountAmount($base, $percent);
+
+            // Nothing to show for a discount of 0 %, or one on a bucket this booking has no
+            // price in — a "– 0,00 €" row only raises questions.
+            if (0 === $amount) {
                 continue;
             }
 
-            $amount = self::discountAmount($base, $percent);
             $discountSum += $amount;
             $discounts[] = ['label' => $label, 'percent' => $percent, 'amount' => $amount];
         }

tests/Service/AccommodationBookingBreakdownCalculatorTest.php

@@ -72,6 +72,23 @@ class AccommodationBookingBreakdownCalculatorTest extends TestCase
         self::assertSame(12345 - 50, $breakdown['discountedTotal']);
     }
 
+    public function testWithDiscountsSkipsDiscountsThatAmountToNothing(): void
+    {
+        $booking = new AccommodationBooking();
+        $booking->setAccommodationDiscount(0);
+        // A discount on a bucket this booking has no price in.
+        $booking->setAdditionalServicesDiscount(20);
+
+        $breakdown = $this->createCalculator()->withDiscounts($booking, [
+            'total' => 12345,
+            'basePrice' => 8000,
+            'servicesPrice' => 0,
+        ]);
+
+        self::assertSame([], $breakdown['discounts']);
+        self::assertSame(12345, $breakdown['discountedTotal']);
+    }
+
     public function testWithoutDiscountsTheDiscountedTotalIsTheTotal(): void
     {
         $breakdown = $this->createCalculator()->withDiscounts(new AccommodationBooking(), $this->breakdown());