Send students to a chosen page when registration succeeds

The Student Registration block's "After email confirmation" panel becomes
"After registration": the page it selects is now where a newly registered
student continues to, and a new autoRedirect toggle sends them there
instead of showing the link.

Only the two finished states qualify (RegistrationPage::isRegistrationComplete):
an invited student who is now logged in, and a self-signup back from the
emailed confirmation link. A validation error, an expired confirmation
link, and the intermediate "check your email" step all stay on the page so
their message is read.

The invited-student success previously had no link at all; it gains a
"Continue to your account" one. That path deliberately has no
WordPress-login-screen fallback — pointing someone already signed in at the
login screen helps nobody — so continueUrl() distinguishes "no page chosen"
from "page chosen", and the redirect does nothing until one is picked.

Closes #115

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

tests/Unit/BlockRegistrarTest.php

@@ -52,6 +52,12 @@ class BlockRegistrarTest extends TestCase
         $this->registrationPage = Mockery::mock(RegistrationPage::class);
         $this->groupClassPage   = Mockery::mock(GroupClassPage::class);
 
+        // Most requests are not a just-finished registration; the tests that
+        // exercise that path override this.
+        $this->registrationPage->shouldReceive('isRegistrationComplete')
+            ->andReturn(false)
+            ->byDefault();
+
         $this->registrar = new TestableBlockRegistrar(
             $this->bookingPage,
             $this->loginPage,
@@ -126,7 +132,7 @@ class BlockRegistrarTest extends TestCase
             array_keys($registered['us-scheduler/student-login']['attributes'])
         );
         self::assertSame(
-            ['loginPageId', 'inviteOnlyMessage'],
+            ['loginPageId', 'autoRedirect', 'inviteOnlyMessage'],
             array_keys($registered['us-scheduler/student-register']['attributes'])
         );
         self::assertSame(
@@ -397,6 +403,145 @@ class BlockRegistrarTest extends TestCase
         self::assertSame([], $this->registrar->redirects);
     }
 
+    public function testAutoRedirectSendsAFinishedRegistrationToTheChosenPage(): void
+    {
+        $this->stubSingularRequest(
+            30,
+            [
+                [
+                    'blockName'   => 'us-scheduler/student-register',
+                    'attrs'       => ['autoRedirect' => true, 'loginPageId' => 4],
+                    'innerBlocks' => [],
+                ],
+            ],
+            false
+        );
+
+        $this->registrationPage->shouldReceive('isRegistrationComplete')->andReturn(true);
+        $this->registrationPage->shouldReceive('continueUrl')
+            ->once()->with(4)->andReturn('https://example.com/welcome/');
+
+        $this->registrar->maybeAutoRedirect();
+
+        self::assertSame(['https://example.com/welcome/'], $this->registrar->redirects);
+    }
+
+    public function testAutoRedirectSendsAJustLoggedInInvitedStudentToTheChosenPage(): void
+    {
+        // The invited-student branch completes logged in, so the logged-in
+        // student-login branch must not get first claim on the request.
+        $this->stubSingularRequest(
+            30,
+            [
+                [
+                    'blockName'   => 'us-scheduler/student-register',
+                    'attrs'       => ['autoRedirect' => true, 'loginPageId' => 4],
+                    'innerBlocks' => [],
+                ],
+            ],
+            true
+        );
+
+        $this->registrationPage->shouldReceive('isRegistrationComplete')->andReturn(true);
+        $this->registrationPage->shouldReceive('continueUrl')
+            ->once()->with(4)->andReturn('https://example.com/welcome/');
+
+        $this->registrar->maybeAutoRedirect();
+
+        self::assertSame(['https://example.com/welcome/'], $this->registrar->redirects);
+    }
+
+    public function testNoRedirectWhenTheRegistrationIsNotFinished(): void
+    {
+        // e.g. the "check your email" step, or a validation error — the
+        // message has to be read, so the block never redirects past it.
+        $this->stubSingularRequest(
+            30,
+            [
+                [
+                    'blockName'   => 'us-scheduler/student-register',
+                    'attrs'       => ['autoRedirect' => true, 'loginPageId' => 4],
+                    'innerBlocks' => [],
+                ],
+            ],
+            false
+        );
+
+        $this->registrationPage->shouldReceive('continueUrl')->never();
+
+        $this->registrar->maybeAutoRedirect();
+
+        self::assertSame([], $this->registrar->redirects);
+    }
+
+    public function testNoRedirectWhenTheRegisterBlockDoesNotOptIn(): void
+    {
+        $this->stubSingularRequest(
+            30,
+            [
+                [
+                    'blockName'   => 'us-scheduler/student-register',
+                    'attrs'       => ['loginPageId' => 4],
+                    'innerBlocks' => [],
+                ],
+            ],
+            false
+        );
+
+        $this->registrationPage->shouldReceive('isRegistrationComplete')->andReturn(true);
+        $this->registrationPage->shouldReceive('continueUrl')->never();
+
+        $this->registrar->maybeAutoRedirect();
+
+        self::assertSame([], $this->registrar->redirects);
+    }
+
+    public function testNoRedirectWhenTheRegisterBlockHasNoPageChosen(): void
+    {
+        $this->stubSingularRequest(
+            30,
+            [
+                [
+                    'blockName'   => 'us-scheduler/student-register',
+                    'attrs'       => ['autoRedirect' => true],
+                    'innerBlocks' => [],
+                ],
+            ],
+            false
+        );
+
+        $this->registrationPage->shouldReceive('isRegistrationComplete')->andReturn(true);
+        // No page chosen: there is no login-screen fallback to redirect to,
+        // so the student keeps the on-page confirmation instead.
+        $this->registrationPage->shouldReceive('continueUrl')->once()->with(0)->andReturnNull();
+
+        $this->registrar->maybeAutoRedirect();
+
+        self::assertSame([], $this->registrar->redirects);
+    }
+
+    public function testNoRedirectWhenTheRegisterBlockPointsAtItsOwnPage(): void
+    {
+        $this->stubSingularRequest(
+            4,
+            [
+                [
+                    'blockName'   => 'us-scheduler/student-register',
+                    'attrs'       => ['autoRedirect' => true, 'loginPageId' => 4],
+                    'innerBlocks' => [],
+                ],
+            ],
+            false
+        );
+
+        $this->registrationPage->shouldReceive('isRegistrationComplete')->andReturn(true);
+        $this->registrationPage->shouldReceive('continueUrl')->never();
+
+        $this->registrar->maybeAutoRedirect();
+
+        self::assertSame([], $this->registrar->redirects);
+    }
+
     public function testNoRedirectOutsideSingularFrontEndRequests(): void
     {
         Functions\when('is_admin')->justReturn(false);