Fix: error in admin edit cart rule

[Caprico85]

Description (*)

After #4487, my coworkers found another problem. This time it's the page for cart rules.

The problem originates from these changes in v20.12.0:

--- a/app/code/core/Mage/Rule/Model/Action/Abstract.php
+++ b/app/code/core/Mage/Rule/Model/Action/Abstract.php
@@ -254,12 +254,17 @@ public function getTypeElement()
      */
     public function getAttributeElement()
     {
+        $renderer = Mage::getBlockSingleton('rule/editable');
+        if ($renderer instanceof Varien_Data_Form_Element_Renderer_Interface) {
+            $this->getForm()::setFieldsetRenderer($renderer);
+        }
+
         return $this->getForm()->addField('action:' . $this->getId() . ':attribute', 'select', [
             'name' => 'rule[actions][' . $this->getId() . '][attribute]',
             'values' => $this->getAttributeSelectOptions(),
             'value' => $this->getAttribute(),
             'value_name' => $this->getAttributeName(),
-        ])->setRenderer(Mage::getBlockSingleton('rule/editable'));
+        ]);
     }

$this->getForm()->addField(...) creates a new form field and returns the newly created field. Previously, ->setRenderer(...) was called on this newly created form field. With your changes in v20.12.0, setFieldsetRenderer() is now called on the form, not on the form field.

Manual testing scenarios (*)

1. Go to Promotions -> Shopping Cart Price Rules
2. Open any rule
3. See the tab switcher being messed up.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All automated tests passed successfully (all builds are green)

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sreichel]

Stupid error. Made my tests on wrong host.

Its this commit that has to be reviewed: 13cf4f6

[sreichel]

@all-contributors add Caprico85 code

[allcontributors]

@sreichel

@Caprico85 already contributed before to code