BUG#AC-3157: Grouped product with tax throws exception with PHP 8.1

Author: glo80326

app/code/Magento/Tax/Pricing/Render/Adjustment.php

@@ -183,8 +183,7 @@ public function displayPriceExcludingTax()
      */
     public function getDataPriceType(): string
     {
-        return $this->amountRender->getPriceType() === 'finalPrice'
-            ? 'basePrice'
-            : 'base' . ucfirst($this->amountRender->getPriceType() ?? '');
+        $priceType = $this->amountRender->getPriceType();
+        return $priceType === 'finalPrice' ? 'basePrice' : ($priceType ? 'base' . ucfirst($priceType) : '');
     }
 }

app/code/Magento/Tax/Test/Unit/Pricing/Render/AdjustmentTest.php

@@ -29,8 +29,6 @@
 class AdjustmentTest extends TestCase
 {
     /**
-     * Context mock
-     *
      * @var \Magento\Framework\View\Element\Template\Context
      */
     protected $contextMock;
@@ -358,23 +356,30 @@ public function testGetHtmlBoth()
 
     /**
      * test for method getDataPriceType
+     * @dataProvider dataPriceTypeDataProvider
      */
-    public function testGetDataPriceType(): void
+    public function testGetDataPriceType(?string $priceType, string $priceTypeValue): void
     {
         $amountRender = $this->getMockBuilder(Amount::class)
             ->addMethods(['getPriceType'])
             ->disableOriginalConstructor()
             ->getMock();
         $amountRender->expects($this->atLeastOnce())
             ->method('getPriceType')
-            ->willReturn('finalPrice');
-        $this->model->render($amountRender, []);
-        $this->assertEquals('basePrice', $this->model->getDataPriceType());
-        $amountRender->expects($this->atLeastOnce())
-            ->method('getPriceType')
-            ->willReturn(null);
+            ->willReturn($priceType);
         $this->model->render($amountRender, []);
-        //no exception thrown
+        //no exception is thrown
+        $this->assertEquals($priceTypeValue, $this->model->getDataPriceType());
         $this->assertIsString($this->model->getDataPriceType());
     }
+
+    /**
+     * data provider for testGetDataPriceType
+     *
+     * @return array
+     */
+    public function dataPriceTypeDataProvider(): array
+    {
+        return [['finalPrice', 'basePrice'], [null, '']];
+    }
 }