Move manage subscription page filter to proper class

[MAILPOET-1635]

lib/Subscription/ManageSubscriptionFormRenderer.php

@@ -100,10 +100,7 @@ class ManageSubscriptionFormRenderer {
       }
     }
 
-    return $this->wp->applyFilters(
+    return $this->templateRenderer->render('subscription/manage_subscription.html', $templateData);
-      'mailpoet_manage_subscription_page',
-      $this->templateRenderer->render('subscription/manage_subscription.html', $templateData)
-    );
   }
 
   private function getCustomFields(Subscriber $subscriber): array {

lib/Subscription/Pages.php

@@ -357,7 +357,11 @@ class Pages {
     } else {
       return $this->wp->__('Subscription management form is only available to mailing lists subscribers.', 'mailpoet');
     }
-    return $this->manageSubscriptionFormRenderer->renderForm($subscriber);
+
+    return $this->wp->applyFilters(
+      'mailpoet_manage_subscription_page',
+      $this->manageSubscriptionFormRenderer->renderForm($subscriber)
+    );
   }
 
   private function getUnsubscribeContent() {

tasks/phpstan/phpstan-baseline-integration-tests.neon

@@ -162,7 +162,7 @@ parameters:
 
 		-
 			message: "#^Access to an undefined property object\\:\\:\\$user_email\\.$#"
-			count: 4
+			count: 5
 			path: ../../tests/integration/Config/ShortcodesTest.php
 
 		-

tests/integration/Config/ShortcodesTest.php

@@ -77,6 +77,28 @@ class ShortcodesTest extends \MailPoetTest {
     expect($result)->contains($subscriber->email);
   }
 
+  public function testItAppliesFilterForManageSubscriptionForm() {
+    $wpUser = wp_set_current_user(1);
+    $wp = new WPFunctions;
+    expect($wp->isUserLoggedIn())->true();
+    $subscriber = Subscriber::create();
+    $subscriber->hydrate(Fixtures::get('subscriber_template'));
+    $subscriber->email = $wpUser->data->user_email;
+    $subscriber->wpUserId = $wpUser->ID;
+    $subscriber->save();
+
+    $shortcodes = ContainerWrapper::getInstance()->get(Shortcodes::class);
+    $shortcodes->init();
+
+    $wp->addAction('mailpoet_manage_subscription_page', function ($page) {
+      return $page . ' MY CUSTOM CONTENT';
+    });
+    $result = do_shortcode('[mailpoet_manage_subscription]');
+    expect($result)->contains('form class="mailpoet-manage-subscription" method="post"');
+    expect($result)->contains('MY CUSTOM CONTENT');
+    $wp->removeAllActions('mailpoet_manage_subscription_page');
+  }
+
   public function testItDoesNotDisplayManageSubscriptionFormForLoggedinNonexistentSubscribers() {
     $wpUser = wp_set_current_user(1);
     expect((new WPFunctions)->isUserLoggedIn())->true();