MAGETWO-38915: Add unit test coverage for \Magento\CurrencySymbol\Helper\*

  - corrected key value used in expected test results

Author: Cari Spruiell

app/code/Magento/CurrencySymbol/Test/Unit/Model/ObserverTest.php

@@ -96,7 +96,7 @@ public function testCurrencyDisplayOptions()
 
         $expectedCurrencyOptions = [
             \Magento\Framework\Locale\Currency::CURRENCY_OPTION_SYMBOL => $sampleCurrencySymbol,
-            \Magento\Framework\Locale\Currency::CURRENCY_OPTION_NAME => \Magento\Framework\Currency::USE_SYMBOL
+            \Magento\Framework\Locale\Currency::CURRENCY_OPTION_DISPLAY => \Magento\Framework\Currency::USE_SYMBOL
         ];
 
         //Return invalid value