fake carrier repo

tests/Fakes/Carrier/FakeCarrierRepository.php

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+<?php
+
+namespace Tests\Fakes\Carrier;
+
+use FreightQuote\Carrier\Carrier;
+use FreightQuote\Carrier\CarrierRepository;
+
+class FakeCarrierRepository implements CarrierRepository
+{
+    private array $existingCarriers = [];
+
+    public function find(int $id): ?Carrier
+    {
+        foreach ($this->existingCarriers as $carrier) {
+            if ($carrier->getId() === $id) {
+                return new Carrier($id, $carrier->getEmail());
+            }
+        }
+
+        return null;
+    }
+
+    public function save(Carrier $carrier): Carrier
+    {
+        $id = $carrier->getId();
+        if ($id === null) {
+            $id = $this->autoIncrementId();
+            $carrier->setId($id);
+        }
+        $this->existingCarriers[$id] = $carrier;
+
+        return new Carrier($id, $carrier->getEmail());
+    }
+
+    private function autoIncrementId(): int
+    {
+        return count($this->existingCarriers);
+    }
+}