Drupal 9 compatibility of Upgrade Rector

Thanks for the issue. I linked it from the project page.

As you can see tests/modules/upgrade_rector_test_error/src/Form/UpgradeRectorTestErrorForm.php and tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module are explicitly about testing whether rector will fix the uses of deprecated code, so we should not fix them or rector will not have anything to fix for testing purposes. We are not actually enabling/installing these test code pieces, so theoretically we can leave them around and still pass tests on Drupal 9 with our test code that is not Drupal 9 compatible.

The situation with file_directory_temp() is we would need to require Drupal 8.8 to fix it. A patch would be great to get started on that. Maybe rector itself can generate it at this point? :)

Also, the report did not show but the info file would need to change to allow installing on Drupal 9.

+++ b/src/RectorProcessor.php
--- a/tests/modules/upgrade_rector_test_error/src/Form/UpgradeRectorTestErrorForm.php
+++ b/tests/modules/upgrade_rector_test_error/src/Form/UpgradeRectorTestErrorForm.php

+++ b/tests/modules/upgrade_rector_test_error/src/Form/UpgradeRectorTestErrorForm.php
+++ b/tests/modules/upgrade_rector_test_error/src/Form/UpgradeRectorTestErrorForm.php
@@ -1,6 +1,8 @@

@@ -1,6 +1,8 @@
 <?php
 
-namespace Drupal\upgrade_rector_test\Form;
+namespace Drupal\upgrade_rector_test_error\Form;
+
+use Drupal\Core\Url;
 
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
@@ -13,8 +15,8 @@ class UpgradeRectorTestErrorForm extends FormBase {

@@ -13,8 +15,8 @@ class UpgradeRectorTestErrorForm extends FormBase {
 
   public function buildForm(array $form, FormStateInterface $form_state) {
     $foo = LOCALE_PLURAL_DELIMITER;
-    drupal_set_message('Sample message');
-    $url = Drupal::url('<front');
+    \Drupal::messenger()->addMessage('Sample message');
+    $url = Url::fromRoute('<front>')->toString();
   }
 
   public function submitForm(array &$form, FormStateInterface $form_state) {}
diff --git a/tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module b/tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module

diff --git a/tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module b/tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module
index 2fa72c4..e97061e 100644

index 2fa72c4..e97061e 100644
--- a/tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module

--- a/tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module
+++ b/tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module

+++ b/tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module
+++ b/tests/modules/upgrade_rector_test_error/upgrade_rector_test_error.module
@@ -1,10 +1,12 @@

@@ -1,10 +1,12 @@
 <?php
 
+use Drupal\Core\Url;
+
 /**
  * Sample code to test ourselves for now.
  */
 function upgrade_rector_test_sample() {
   $foo = LOCALE_PLURAL_DELIMITER;
-  drupal_set_message('Sample message');
-  $url = Drupal::url('<front');
+  \Drupal::messenger()->addMessage('Sample message');
+  $url = Url::fromRoute('<front>')->toString();
 }

As I wrote above, these should not be fixed. We need them present so we can test with them that rector works.

The rest of the patch looks good. We can even add a conditional around the file temp directory call and keep it working on 8.7 while being Drupal 9 compatible.

Fixed those.

Core key should not be there.

Woot!