Fix: Force current currency reload on currency code change

Fixed an issue where calling setCurrentCurrencyCode() multiple times
did not update the currency returned by getCurrentCurrency() due to
internal caching.

The issue occurred because getCurrentCurrency() caches the currency
object in the store's data using the 'current_currency' key. When
setCurrentCurrencyCode() was called to change the currency code, the
cached currency object was not cleared, causing getCurrentCurrency()
to return the old currency instead of loading the new one.

Solution:
- Added unsetData('current_currency') in setCurrentCurrencyCode()
  to clear the cached currency when the currency code changes
- This forces getCurrentCurrency() to reload the currency based on
  the new currency code on its next call

Changes:
- Updated Store::setCurrentCurrencyCode() to clear cached currency
- Added unit test to verify currency cache is cleared on code change

Test coverage:
- Added testSetCurrentCurrencyCodeClearsCachedCurrency() unit test
- Test verifies unsetData() is called when currency code changes
- Test verifies behavior with multiple currency code changes

Manual testing:
1. Create store with multiple available currencies (USD, EUR)
2. Call $store->setCurrentCurrencyCode('USD')
3. Verify $store->getCurrentCurrency()->getCode() returns 'USD'
4. Call $store->setCurrentCurrencyCode('EUR')
5. Verify $store->getCurrentCurrency()->getCode() returns 'EUR'
6. Without this fix, step 5 would return 'USD'

Fixes: #40333

Author: satishashilwar

app/code/Magento/Store/Model/Store.php

@@ -911,6 +911,9 @@ public function setCurrentCurrencyCode($code)
                 : $this->_storeManager->getWebsite()->getDefaultStore()->getDefaultCurrency()->getCode();
 
             $this->_httpContext->setValue(Context::CONTEXT_CURRENCY, $code, $defaultCode);
+            
+            // Force reload of current currency on currency code change
+            $this->unsetData('current_currency');
         }
         return $this;
     }

app/code/Magento/Store/Test/Unit/Model/StoreTest.php

@@ -819,6 +819,107 @@ public static function currencyCodeDataProvider(): array
         ];
     }
 
+    /**
+     * Test that setCurrentCurrencyCode clears cached currency
+     *
+     * @return void
+     */
+    public function testSetCurrentCurrencyCodeClearsCachedCurrency(): void
+    {
+        $currencyCodeFirst = 'USD';
+        $currencyCodeSecond = 'EUR';
+        
+        $sessionMock = $this->getMockBuilder(SessionManagerInterface::class)
+            ->getMockForAbstractClass();
+        $sessionMock->expects($this->exactly(2))
+            ->method('setCurrencyCode')
+            ->willReturnCallback(function ($code) use ($currencyCodeFirst, $currencyCodeSecond) {
+                static $callCount = 0;
+                $callCount++;
+                if ($callCount === 1) {
+                    $this->assertEquals($currencyCodeFirst, $code);
+                } else {
+                    $this->assertEquals($currencyCodeSecond, $code);
+                }
+            });
+        
+        $httpContextMock = $this->getMockBuilder(\Magento\Framework\App\Http\Context::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        
+        $currencyFactoryMock = $this->getMockBuilder(CurrencyFactory::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        
+        $currencyMockFirst = $this->getMockBuilder(Currency::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $currencyMockFirst->expects($this->any())
+            ->method('getCode')
+            ->willReturn($currencyCodeFirst);
+            
+        $currencyMockSecond = $this->getMockBuilder(Currency::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $currencyMockSecond->expects($this->any())
+            ->method('getCode')
+            ->willReturn($currencyCodeSecond);
+        
+        $storeManagerMock = $this->getMockBuilder(StoreManagerInterface::class)
+            ->getMockForAbstractClass();
+        $storeManagerMock->expects($this->any())
+            ->method('getStore')
+            ->willReturn(null);
+            
+        $websiteMock = $this->getMockBuilder(WebsiteInterface::class)
+            ->getMockForAbstractClass();
+        $websiteMock->expects($this->any())
+            ->method('getDefaultStore')
+            ->willReturnSelf();
+        $websiteMock->expects($this->any())
+            ->method('getDefaultCurrency')
+            ->willReturn($currencyMockFirst);
+            
+        $storeManagerMock->expects($this->any())
+            ->method('getWebsite')
+            ->willReturn($websiteMock);
+        
+        $storeMock = $this->getMockBuilder(Store::class)
+            ->setConstructorArgs([
+                $this->createMock(\Magento\Framework\Model\Context::class),
+                $this->createMock(\Magento\Framework\Registry::class),
+                $this->createMock(\Magento\Framework\App\Cache\Type\Config::class),
+                $this->createMock(\Magento\Framework\Url::class),
+                $this->requestMock,
+                $this->createMock(\Magento\Config\Model\ResourceModel\Config\Data::class),
+                $this->configMock,
+                $storeManagerMock,
+                $this->filesystemMock,
+                $this->createMock(\Magento\Framework\Url\ModifierInterface::class),
+                $sessionMock,
+                $httpContextMock,
+                $this->createMock(\Magento\Framework\App\Config::class),
+                $currencyFactoryMock
+            ])
+            ->onlyMethods(['getAvailableCurrencyCodes', 'getData', 'unsetData', 'setData'])
+            ->getMock();
+        
+        $storeMock->expects($this->any())
+            ->method('getAvailableCurrencyCodes')
+            ->willReturn([$currencyCodeFirst, $currencyCodeSecond]);
+        
+        // Expect unsetData to be called when currency code changes
+        $storeMock->expects($this->exactly(2))
+            ->method('unsetData')
+            ->with('current_currency');
+        
+        // First currency change
+        $storeMock->setCurrentCurrencyCode($currencyCodeFirst);
+        
+        // Second currency change - should clear cached currency
+        $storeMock->setCurrentCurrencyCode($currencyCodeSecond);
+    }
+
     /**
      * @param Store $model
      */