feat: make email optional for under-16 participants except applicant

tests/Form/Service/CreateFieldStateProviderTest.php

@@ -74,14 +74,69 @@ class CreateFieldStateProviderTest extends TestCase
         );
     }
 
-    public function testEmailIsRequiredForEveryParticipantIncludingChildren(): void
+    public function testEmailIsNotRequiredForNonApplicantChild(): void
     {
         $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
 
-        $this->assertArrayNotHasKey(
-            'required',
-            $this->provider->getFieldState('email', $bookingDto, 1),
-            'Requiredness is the form type base option now that it is unconditional'
+        $this->assertFalse(
+            $this->provider->getFieldState('email', $bookingDto, 1)['required'],
+            'A child travelling with an applicant does not need an email address of their own'
+        );
+    }
+
+    public function testEmailIsRequiredForNonApplicantAdult(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('1990-01-01'));
+
+        $this->assertTrue($this->provider->getFieldState('email', $bookingDto, 1)['required']);
+    }
+
+    public function testEmailIsRequiredForTheApplicantEvenAsAChild(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
+        $bookingDto->participants[0]->dateOfBirth = new \DateTimeImmutable('2015-01-01');
+
+        $this->assertTrue(
+            $this->provider->getFieldState('email', $bookingDto, 0)['required'],
+            'The applicant is the booking contact and always has to be reachable'
+        );
+    }
+
+    public function testEmailIsNotRequiredForAChildAtIndexZeroWhenTheApplicantDoesNotTravel(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
+        $bookingDto->participants[0]->dateOfBirth = new \DateTimeImmutable('2015-01-01');
+        $bookingDto->applicantTravels = false;
+
+        $this->assertFalse(
+            $this->provider->getFieldState('email', $bookingDto, 0)['required'],
+            'On a split booking participant[0] is an ordinary traveller'
+        );
+    }
+
+    public function testEmailIsRequiredWhenDateOfBirthIsUnknown(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
+        $bookingDto->participants[1]->dateOfBirth = null;
+
+        $this->assertTrue(
+            $this->provider->getFieldState('email', $bookingDto, 1)['required'],
+            'An unknown age counts as an adult'
+        );
+    }
+
+    public function testEmailRequirementFlipsWhenDateOfBirthChanges(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
+        $dependent = $bookingDto->participants[1];
+
+        $this->assertFalse($this->provider->getFieldState('email', $bookingDto, 1)['required']);
+
+        $dependent->dateOfBirth = new \DateTimeImmutable('1990-01-01');
+
+        $this->assertTrue(
+            $this->provider->getFieldState('email', $bookingDto, 1)['required'],
+            'Correcting a child date of birth to an adult one must reinstate the requirement'
         );
     }