feat: offer non-travelling applicant choice only on selected travels

tests/Form/Model/BookingDtoTest.php

@@ -148,6 +148,48 @@ class BookingDtoTest extends TestCase
         $this->assertFalse($dto->isFirstParticipantApplicant());
     }
 
+    public function testRestoringTheTravellingApplicantEndsTheSplit(): void
+    {
+        $dto = $this->createCreateModeDto();
+        $dto->applicantTravels = false;
+
+        $applicant = new ParticipantDto();
+        $applicant->firstName = 'Elternteil';
+        $dto->applicant = $applicant;
+
+        $child = new ParticipantDto();
+        $child->index = 0;
+        $child->firstName = 'Kind';
+        $child->assignedRoomId = 1408;
+        $sibling = new ParticipantDto();
+        $sibling->index = 1;
+        $dto->participants = [$child, $sibling];
+
+        $dto->restoreTravellingApplicant();
+
+        $this->assertTrue($dto->applicantTravels);
+        $this->assertNull($dto->applicant);
+        $this->assertSame($applicant, $dto->participants[0]);
+        $this->assertSame(0, $applicant->index);
+        $this->assertSame(1408, $applicant->assignedRoomId, 'The slot keeps its room');
+        $this->assertSame($sibling, $dto->participants[1]);
+    }
+
+    public function testRestoringWithoutAnApplicantRecordKeepsTheFirstParticipant(): void
+    {
+        $dto = $this->createCreateModeDto();
+        $dto->applicantTravels = false;
+
+        $traveller = new ParticipantDto();
+        $traveller->index = 0;
+        $dto->participants = [$traveller];
+
+        $dto->restoreTravellingApplicant();
+
+        $this->assertTrue($dto->applicantTravels);
+        $this->assertSame($traveller, $dto->participants[0]);
+    }
+
     public function testInternalAgencyBookingNeverHasTheFirstParticipantAsApplicantInEditMode(): void
     {
         $dto = $this->createEditModeDto(100, 100);