fix: report an unresolvable hotel instead of failing on it

tests/Validator/Constraints/ResolvableHotelValidatorTest.php

@@ -0,0 +1,101 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Validator\Constraints;
+
+use App\BusProNet\DataProvider\HotelDataProvider;
+use App\BusProNet\Model\Hotel;
+use App\Validator\Constraints\ResolvableHotel;
+use App\Validator\Constraints\ResolvableHotelValidator;
+use PHPUnit\Framework\MockObject\MockObject;
+use Symfony\Component\Validator\Test\ConstraintValidatorTestCase;
+
+/**
+ * Everything a destination records about its house is derived from this lookup, so an id that
+ * does not resolve used to reach DestinationTrait::updateEntity() and fail there on a null -
+ * a 500 on a form submit rather than a message on a field.
+ *
+ * The two causes are reported apart on purpose. An unreachable MyE&P is not the operator's
+ * doing, and telling them their choice was invalid sends them hunting for a different answer
+ * when the one they gave was right.
+ */
+class ResolvableHotelValidatorTest extends ConstraintValidatorTestCase
+{
+    public function testAResolvableHotelPasses(): void
+    {
+        $this->validator = $this->createValidator([163959 => $this->hotel()]);
+        $this->validator->initialize($this->context);
+
+        $this->validator->validate('163959', new ResolvableHotel());
+
+        $this->assertNoViolation();
+    }
+
+    public function testAHotelMissingFromALoadedListIsRejectedAsUnknown(): void
+    {
+        $constraint = new ResolvableHotel();
+
+        $this->validator = $this->createValidator([163959 => $this->hotel()]);
+        $this->validator->initialize($this->context);
+
+        $this->validator->validate('999999', $constraint);
+
+        $this->buildViolation($constraint->unknownMessage)->assertRaised();
+    }
+
+    /**
+     * StaleWhileErrorCache answers [] rather than throwing, so an empty list is the only signal
+     * that MyE&P could not be reached - and on a cold cache there is no stale copy to fall back to.
+     */
+    public function testAnEmptyListIsReportedAsAnOutageRatherThanABadChoice(): void
+    {
+        $constraint = new ResolvableHotel();
+
+        $this->validator = $this->createValidator([]);
+        $this->validator->initialize($this->context);
+
+        $this->validator->validate('163959', $constraint);
+
+        $this->buildViolation($constraint->unavailableMessage)->assertRaised();
+    }
+
+    /**
+     * Whether a hotel was chosen at all belongs to NotBlank, which already sits on the property.
+     */
+    public function testAnEmptyValueIsLeftToNotBlank(): void
+    {
+        $this->validator = $this->createValidator([]);
+        $this->validator->initialize($this->context);
+
+        $this->validator->validate(null, new ResolvableHotel());
+        $this->validator->validate('', new ResolvableHotel());
+
+        $this->assertNoViolation();
+    }
+
+    protected function createValidator(array $hotels = []): ResolvableHotelValidator
+    {
+        return new ResolvableHotelValidator($this->provider($hotels));
+    }
+
+    /**
+     * @return HotelDataProvider&MockObject
+     */
+    private function provider(array $hotels): object
+    {
+        $provider = $this->createMock(HotelDataProvider::class);
+        $provider->method('getAll')->willReturn($hotels);
+
+        return $provider;
+    }
+
+    private function hotel(): Hotel
+    {
+        return (new Hotel())
+            ->setBusProId(163959)
+            ->setCode('LPJGR')
+            ->setName('Sportclub Jenatsch')
+        ;
+    }
+}