MAGETWO-82752: Fixes translations by re-running the loadData for its correct locale #10913

Author: ishakhsuvarov

app/code/Magento/Translation/Model/Json/PreProcessor.php

@@ -77,12 +77,13 @@ public function process(Chain $chain)
             if ($context instanceof FallbackContext) {
                 $themePath = $context->getThemePath();
                 $areaCode = $context->getAreaCode();
-                $this->translate->setLocale($context->getLocale());
             }
 
             $area = $this->areaList->getArea($areaCode);
             $area->load(\Magento\Framework\App\Area::PART_TRANSLATE);
 
+            $this->translate->setLocale($context->getLocale())->loadData($areaCode, true);
+
             $chain->setContent(json_encode($this->dataProvider->getData($themePath)));
             $chain->setContentType('json');
         }

app/code/Magento/Translation/Test/Unit/Model/Json/PreProcessorTest.php

@@ -80,6 +80,9 @@ public function testGetData()
         $context->expects($this->once())
             ->method('getAreaCode')
             ->willReturn($areaCode);
+        $context->expects($this->once())
+            ->method('getLocale')
+            ->willReturn('en_US');
 
         $this->areaListMock->expects($this->once())
             ->method('getArea')
@@ -97,6 +100,9 @@ public function testGetData()
             ->method('setContentType')
             ->with('json');
 
+        $this->translateMock->expects($this->once())->method('setLocale')->with('en_US')->willReturnSelf();
+        $this->translateMock->expects($this->once())->method('loadData')->with($areaCode, true);
+
         $this->model->process($chain);
     }
 }