Issue #2127487 by chx: GetStringTranslationStub() ignores variables.

core/tests/Drupal/Tests/UnitTestCase.php

@@ -177,7 +177,7 @@ public function getStringTranslationStub() {
     $translation = $this->getMock('Drupal\Core\StringTranslation\TranslationInterface');
     $translation->expects($this->any())
       ->method('translate')
-      ->will($this->returnArgument(0));
+      ->will($this->returnCallback(function ($string, array $args = array()) { return strtr($string, $args); }));
     return $translation;
   }