Ask who the signup is for as a three-way choice

Replaces the single "I'm registering as a parent or guardian" tick with
"Just myself" / "On behalf of one or more students" / "Both".

Radios, not checkboxes as the feedback put it: the three answers are
mutually exclusive, and "both" only means anything as a third choice
alongside the other two.

The tick could only ever say whether there were children to add. It could
not say whether the account holder was a student, so bookableStudents()
always offered them their own name and any guardian could book themselves a
lesson nobody meant to sell. "On behalf of" now records us_guardian_only and
leaves them out of the picker.

That flag is stored as the negative on purpose. Every account predating this
choice is a bookable student, and absence has to keep meaning exactly that,
or the picker would quietly stop offering people themselves on upgrade.
setGuardianOnly() clears the key rather than writing 0, so "not set" stays
the single spelling of "yes, a student". A guardian-only account with nobody
linked to it is still offered itself — an empty picker is no way to book at
all, and they can put the account right from the profile page.

An unrecognised or absent value reads as "just myself": the choice that
collects the least and grants the least. A missing radio must never be taken
as "register these children".

Bumps to 1.4.0.

The account holder's own questions stay out of play whenever students are
being added, "both" included — asking them there is #146.

Verified the form in a headless browser across all three choices: which
blocks show, which fields carry `required`, whether the account holder's
question panel is disabled, which submit is offered, and that switching back
to "just myself" leaves no hidden required field blocking submit.

Closes #145

Co-Authored-By: Claude Opus 5 <[email protected]>

tests/Unit/Auth/RegistrationPageTest.php

@@ -35,6 +35,8 @@ class RegistrationPageTest extends TestCase
 
         Functions\when('wp_unslash')->alias(static fn ($v) => $v);
         Functions\when('sanitize_text_field')->alias(static fn ($v) => $v);
+        // Every submit reads the "who are you registering?" radio through it.
+        Functions\when('sanitize_key')->alias(static fn ($v) => strtolower((string) $v));
         Functions\when('sanitize_textarea_field')->alias(static fn ($v) => $v);
         Functions\when('sanitize_email')->alias(static fn ($v) => $v);
         // Reached on every submit now that the email is validated before the
@@ -74,6 +76,8 @@ class RegistrationPageTest extends TestCase
         $this->ctx['versions']    = Mockery::mock(PolicyVersionRepository::class);
         $this->ctx['acceptances'] = Mockery::mock(AcceptanceRepository::class);
         $this->ctx['guardians']   = Mockery::mock(GuardianService::class);
+        // Recorded on every successful signup; the tests that care assert on it.
+        $this->ctx['guardians']->shouldReceive('setGuardianOnly')->byDefault();
 
         $this->ctx['page'] = new RegistrationPage(
             $invites,
@@ -109,6 +113,17 @@ class RegistrationPageTest extends TestCase
         $this->ctx['settings']->shouldReceive('openRegistrationEnabled')->andReturn(true);
     }
 
+    /** Everything the invite success branch touches once the account is created. */
+    private function stubInviteSuccess(): void
+    {
+        Functions\when('email_exists')->justReturn(false);
+        Functions\when('wp_insert_user')->justReturn(42);
+        Functions\when('is_wp_error')->alias(static fn ($thing): bool => $thing instanceof \WP_Error);
+        Functions\when('wp_set_current_user')->justReturn(null);
+        Functions\when('wp_set_auth_cookie')->justReturn(null);
+        $this->ctx['invites']->shouldReceive('markAccepted')->once();
+    }
+
     private function submit(?Invite $invite, bool $open): string
     {
         $method = new \ReflectionMethod(RegistrationPage::class, 'handleSubmit');
@@ -624,7 +639,7 @@ class RegistrationPageTest extends TestCase
         $_POST = [
             'password'       => 'thistle-marrow-42',
             'display_name'   => 'Grace',
-            'us_is_guardian' => '1',
+            'us_registering_for' => RegistrationPage::FOR_STUDENTS,
             'children'       => [
                 ['name' => 'Ada', 'birth_year' => '2015', 'answers' => [7 => 'Piano']],
                 ['name' => 'Alan', 'birth_year' => '2017', 'answers' => [7 => 'Violin']],
@@ -711,12 +726,111 @@ class RegistrationPageTest extends TestCase
         );
     }
 
+    /**
+     * "On behalf of students" is the one choice that says the account holder is
+     * not a student, so it is the one that sets the flag.
+     */
+    public function testRegisteringOnlyForStudentsMarksTheAccountGuardianOnly(): void
+    {
+        $_POST = [
+            'password'           => 'thistle-marrow-42',
+            'display_name'       => 'Grace',
+            'us_registering_for' => RegistrationPage::FOR_STUDENTS,
+            'children'           => [['name' => 'Ada', 'birth_year' => '2015', 'answers' => []]],
+        ];
+
+        $this->ctx['questions']->shouldReceive('findByScope')->andReturn([]);
+        $this->ctx['guardians']->shouldReceive('createChild')->once()->andReturn(101);
+        $this->stubInviteSuccess();
+
+        $this->ctx['guardians']->shouldReceive('setGuardianOnly')->once()->with(42, true);
+
+        self::assertSame('invite', $this->submit(new Invite(email: '[email protected]', token: 'hash'), false));
+    }
+
+    /**
+     * @dataProvider modesThatKeepTheAccountHolderAStudent
+     */
+    public function testTheAccountHolderStaysAStudentForTheOtherTwoChoices(string $mode, bool $withChildren): void
+    {
+        $_POST = [
+            'password'           => 'thistle-marrow-42',
+            'display_name'       => 'Grace',
+            'us_registering_for' => $mode,
+        ];
+
+        if ($withChildren) {
+            $_POST['children'] = [['name' => 'Ada', 'birth_year' => '2015', 'answers' => []]];
+            $this->ctx['guardians']->shouldReceive('createChild')->once()->andReturn(101);
+        }
+
+        $this->ctx['questions']->shouldReceive('findByScope')->andReturn([]);
+        $this->stubInviteSuccess();
+
+        $this->ctx['guardians']->shouldReceive('setGuardianOnly')->once()->with(42, false);
+
+        self::assertSame('invite', $this->submit(new Invite(email: '[email protected]', token: 'hash'), false));
+    }
+
+    /** @return array<string, array{string, bool}> */
+    public static function modesThatKeepTheAccountHolderAStudent(): array
+    {
+        return [
+            'just myself'          => [RegistrationPage::FOR_SELF, false],
+            'myself and students'  => [RegistrationPage::FOR_BOTH, true],
+        ];
+    }
+
+    /**
+     * "Both" collects students exactly as "on behalf of" does — the only
+     * difference is whether the account holder is one of them.
+     */
+    public function testBothStillRequiresAtLeastOneStudent(): void
+    {
+        $_POST = [
+            'password'           => 'thistle-marrow-42',
+            'display_name'       => 'Grace',
+            'us_registering_for' => RegistrationPage::FOR_BOTH,
+            'children'           => [],
+        ];
+
+        $this->ctx['questions']->shouldReceive('findByScope')->andReturn([]);
+        Functions\when('email_exists')->justReturn(false);
+        Functions\expect('wp_insert_user')->never();
+
+        self::assertStringContainsString('at least one student', $this->submit(new Invite(email: '[email protected]', token: 'hash'), false));
+    }
+
+    /**
+     * A form posted without the radio — an old cached page, or a crafted
+     * request — must fall to the choice that collects and grants the least,
+     * never be read as "register these children".
+     */
+    public function testAMissingOrUnknownChoiceFallsBackToJustMyself(): void
+    {
+        $_POST = [
+            'password'           => 'thistle-marrow-42',
+            'display_name'       => 'Grace',
+            'us_registering_for' => 'something-else',
+            'children'           => [['name' => 'Ada', 'birth_year' => '2015', 'answers' => []]],
+        ];
+
+        $this->ctx['questions']->shouldReceive('findByScope')->andReturn([]);
+        $this->stubInviteSuccess();
+
+        // No student is created from children[] the caller never asked to register.
+        $this->ctx['guardians']->shouldNotReceive('createChild');
+        $this->ctx['guardians']->shouldReceive('setGuardianOnly')->once()->with(42, false);
+
+        self::assertSame('invite', $this->submit(new Invite(email: '[email protected]', token: 'hash'), false));
+    }
+
     public function testGuardianSignupWithNoChildrenIsRejected(): void
     {
         $_POST = [
             'password'       => 'thistle-marrow-42',
             'display_name'   => 'Grace',
-            'us_is_guardian' => '1',
+            'us_registering_for' => RegistrationPage::FOR_STUDENTS,
             'children'       => [['name' => '', 'birth_year' => '', 'answers' => []]],
         ];
 
@@ -740,7 +854,7 @@ class RegistrationPageTest extends TestCase
         $_POST = [
             'password'       => 'thistle-marrow-42',
             'display_name'   => 'Grace',
-            'us_is_guardian' => '1',
+            'us_registering_for' => RegistrationPage::FOR_STUDENTS,
             'children'       => [
                 ['name' => 'Ada', 'birth_year' => '2015', 'answers' => []],
                 ['name' => '', 'birth_year' => '2017', 'answers' => []],
@@ -766,7 +880,7 @@ class RegistrationPageTest extends TestCase
         $_POST = [
             'password'       => 'thistle-marrow-42',
             'display_name'   => 'Grace',
-            'us_is_guardian' => '1',
+            'us_registering_for' => RegistrationPage::FOR_STUDENTS,
             'children'       => [['name' => 'Ada', 'birth_year' => $submitted, 'answers' => []]],
         ];
 
@@ -800,7 +914,7 @@ class RegistrationPageTest extends TestCase
         $_POST = [
             'password'       => 'thistle-marrow-42',
             'display_name'   => 'Grace',
-            'us_is_guardian' => '1',
+            'us_registering_for' => RegistrationPage::FOR_STUDENTS,
             'children'       => [
                 ['name' => 'Ada', 'birth_year' => '2015', 'answers' => [7 => 'Piano']],
                 ['name' => 'Alan', 'birth_year' => '2017', 'answers' => [7 => '  ']],
@@ -827,7 +941,7 @@ class RegistrationPageTest extends TestCase
         $_POST = [
             'password'       => 'thistle-marrow-42',
             'display_name'   => 'Grace',
-            'us_is_guardian' => '1',
+            'us_registering_for' => RegistrationPage::FOR_STUDENTS,
             'children'       => [
                 ['name' => 'Ada', 'birth_year' => '2015', 'answers' => []],
                 ['name' => 'Alan', 'birth_year' => '2017', 'answers' => []],
@@ -864,7 +978,7 @@ class RegistrationPageTest extends TestCase
         $_POST = [
             'password'       => 'thistle-marrow-42',
             'display_name'   => 'Grace',
-            'us_is_guardian' => '1',
+            'us_registering_for' => RegistrationPage::FOR_STUDENTS,
             'accept'         => [3],
             'children'       => [['name' => 'Ada', 'birth_year' => '2015', 'answers' => []]],
         ];

tests/Unit/TestCase.php

@@ -17,6 +17,32 @@ abstract class TestCase extends BaseTestCase
         Monkey\setUp();
         Monkey\Functions\stubTranslationFunctions();
         Monkey\Functions\stubEscapeFunctions();
+
+        // WordPress's form-state helpers. Stubbed here rather than per test
+        // because they are pure output helpers with no behaviour worth faking
+        // differently anywhere — a template either emits the attribute or not.
+        Monkey\Functions\when('checked')->alias(
+            static fn (mixed $checked, mixed $current = true, bool $echo = true): string
+                => self::formAttribute('checked', $checked, $current, $echo)
+        );
+        Monkey\Functions\when('selected')->alias(
+            static fn (mixed $selected, mixed $current = true, bool $echo = true): string
+                => self::formAttribute('selected', $selected, $current, $echo)
+        );
+    }
+
+    /** Mirrors WordPress's `__checked_selected_helper()`, echo included. */
+    private static function formAttribute(string $type, mixed $helper, mixed $current, bool $echo): string
+    {
+        // WordPress compares loosely, and templates rely on that: `checked($a, $b)`
+        // is routinely called with an int against a numeric string.
+        $result = $helper == $current ? " {$type}='{$type}'" : ''; // phpcs:ignore WordPress.PHP.StrictComparisons.LooseComparison
+
+        if ($echo) {
+            echo $result; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- fixed literal.
+        }
+
+        return $result;
     }
 
     protected function tearDown(): void