diff --git a/core/.eslintignore b/core/.eslintignore
index ac3272e162..fae394892b 100644
--- a/core/.eslintignore
+++ b/core/.eslintignore
@@ -1,6 +1,6 @@
 assets/vendor/**/*
-modules/locale/tests/locale_test.js
 node_modules/**/*
 **/js_test_files/**/*
 *.js
 !*.es6.js
+modules/locale/tests/locale_test.es6.js
diff --git a/core/modules/locale/tests/src/Functional/LocaleJavascriptTranslationTest.php b/core/modules/locale/tests/src/Functional/LocaleJavascriptTranslationTest.php
index bbb825832b..55582ba0c0 100644
--- a/core/modules/locale/tests/src/Functional/LocaleJavascriptTranslationTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleJavascriptTranslationTest.php
@@ -21,73 +21,80 @@ class LocaleJavascriptTranslationTest extends BrowserTestBase {
   public static $modules = ['locale', 'locale_test'];
 
   public function testFileParsing() {
-    $filename = __DIR__ . '/../../locale_test.js';
 
-    // Parse the file to look for source strings.
-    _locale_parse_js_file($filename);
+    // Testing the original file.
+    $files[] = __DIR__ . '/../../locale_test.es6.js';
 
-    // Get all of the source strings that were found.
-    $strings = $this->container
-      ->get('locale.storage')
-      ->getStrings([
-        'type' => 'javascript',
-        'name' => $filename,
-      ]);
+    // Testing the processed file.
+    $files[] = __DIR__ . '/../../locale_test.js';
 
-    $source_strings = [];
-    foreach ($strings as $string) {
-      $source_strings[$string->source] = $string->context;
-    }
+    foreach ($files as $filename) {
+      // Parse the file to look for source strings.
+      _locale_parse_js_file($filename);
 
-    $etx = LOCALE_PLURAL_DELIMITER;
-    // List of all strings that should be in the file.
-    $test_strings = [
-      'Standard Call t' => '',
-      'Whitespace Call t' => '',
+      // Get all of the source strings that were found.
+      $strings = $this->container
+        ->get('locale.storage')
+        ->getStrings([
+          'type' => 'javascript',
+          'name' => $filename,
+        ]);
 
-      'Single Quote t' => '',
-      "Single Quote \\'Escaped\\' t" => '',
-      'Single Quote Concat strings t' => '',
+      $source_strings = [];
+      foreach ($strings as $string) {
+        $source_strings[$string->source] = $string->context;
+      }
 
-      'Double Quote t' => '',
-      "Double Quote \\\"Escaped\\\" t" => '',
-      'Double Quote Concat strings t' => '',
+      $etx = LOCALE_PLURAL_DELIMITER;
+      // List of all strings that should be in the file.
+      $test_strings = [
+        'Standard Call t' => '',
+        'Whitespace Call t' => '',
 
-      'Context !key Args t' => 'Context string',
+        'Single Quote t' => '',
+        "Single Quote \\'Escaped\\' t" => '',
+        'Single Quote Concat strings t' => '',
 
-      'Context Unquoted t' => 'Context string unquoted',
-      'Context Single Quoted t' => 'Context string single quoted',
-      'Context Double Quoted t' => 'Context string double quoted',
+        'Double Quote t' => '',
+        "Double Quote \\\"Escaped\\\" t" => '',
+        'Double Quote Concat strings t' => '',
 
-      "Standard Call plural{$etx}Standard Call @count plural" => '',
-      "Whitespace Call plural{$etx}Whitespace Call @count plural" => '',
+        'Context !key Args t' => 'Context string',
 
-      "Single Quote plural{$etx}Single Quote @count plural" => '',
-      "Single Quote \\'Escaped\\' plural{$etx}Single Quote \\'Escaped\\' @count plural" => '',
+        'Context Unquoted t' => 'Context string unquoted',
+        'Context Single Quoted t' => 'Context string single quoted',
+        'Context Double Quoted t' => 'Context string double quoted',
 
-      "Double Quote plural{$etx}Double Quote @count plural" => '',
-      "Double Quote \\\"Escaped\\\" plural{$etx}Double Quote \\\"Escaped\\\" @count plural" => '',
+        "Standard Call plural{$etx}Standard Call @count plural" => '',
+        "Whitespace Call plural{$etx}Whitespace Call @count plural" => '',
 
-      "Context !key Args plural{$etx}Context !key Args @count plural" => 'Context string',
+        "Single Quote plural{$etx}Single Quote @count plural" => '',
+        "Single Quote \\'Escaped\\' plural{$etx}Single Quote \\'Escaped\\' @count plural" => '',
 
-      "Context Unquoted plural{$etx}Context Unquoted @count plural" => 'Context string unquoted',
-      "Context Single Quoted plural{$etx}Context Single Quoted @count plural" => 'Context string single quoted',
-      "Context Double Quoted plural{$etx}Context Double Quoted @count plural" => 'Context string double quoted',
-    ];
+        "Double Quote plural{$etx}Double Quote @count plural" => '',
+        "Double Quote \\\"Escaped\\\" plural{$etx}Double Quote \\\"Escaped\\\" @count plural" => '',
 
-    // Assert that all strings were found properly.
-    foreach ($test_strings as $str => $context) {
-      $args = ['%source' => $str, '%context' => $context];
+        "Context !key Args plural{$etx}Context !key Args @count plural" => 'Context string',
 
-      // Make sure that the string was found in the file.
-      $this->assertTrue(isset($source_strings[$str]), SafeMarkup::format('Found source string: %source', $args));
+        "Context Unquoted plural{$etx}Context Unquoted @count plural" => 'Context string unquoted',
+        "Context Single Quoted plural{$etx}Context Single Quoted @count plural" => 'Context string single quoted',
+        "Context Double Quoted plural{$etx}Context Double Quoted @count plural" => 'Context string double quoted',
+      ];
 
-      // Make sure that the proper context was matched.
-      $message = $context ? SafeMarkup::format('Context for %source is %context', $args) : SafeMarkup::format('Context for %source is blank', $args);
-      $this->assertTrue(isset($source_strings[$str]) && $source_strings[$str] === $context, $message);
-    }
+      // Assert that all strings were found properly.
+      foreach ($test_strings as $str => $context) {
+        $args = ['%source' => $str, '%context' => $context];
+
+        // Make sure that the string was found in the file.
+        $this->assertTrue(isset($source_strings[$str]), SafeMarkup::format('Found source string: %source', $args));
 
-    $this->assertEqual(count($source_strings), count($test_strings), 'Found correct number of source strings.');
+        // Make sure that the proper context was matched.
+        $message = $context ? SafeMarkup::format('Context for %source is %context', $args) : SafeMarkup::format('Context for %source is blank', $args);
+        $this->assertTrue(isset($source_strings[$str]) && $source_strings[$str] === $context, $message);
+      }
+
+      $this->assertEqual(count($source_strings), count($test_strings), 'Found correct number of source strings.');
+    }
   }
 
   /**