Language from URL negotiator does not add request query to language switcher links

Thank you for the patch . Should be implemented in core.

Let's test this.

+++ b/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationUrl.php
@@ -191,7 +191,9 @@ public function processOutbound($path, &$options = array(), Request $request = N
-    $links = array();
+    $links = [];
+    $query = [];

Let's not do conversion to short syntax in this issue.

New patch

Still needs an automated test.

I added a query string to doTestLanguageBlockAnonymous test function. Any feedback is welcome.

Review patch #15 its looking good.it is nicely working

1. index a1d4da4..04526bb 100644
   --- a/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationUrl.php
   
   @@ -192,6 +192,8 @@ public function processOutbound($path, &$options = array(), Request $request = N
   +    $query = array();
   +    parse_str($request->getQueryString(), $query);
   

   I think we can just do $query = $request->query->all(); instead of this.

2. +++ b/core/modules/language/src/Tests/LanguageSwitchingTest.php
   @@ -118,8 +118,10 @@ protected function doTestLanguageBlockAuthenticated($block_label) {
   +    $this->drupalGet('',$options);
   

   Need a space between , and $options - but I would just do this like this:
   $this->drupalGet('', ['query' => ['foo' => 'bar']]);

   Also I would detail what the testing purpose is - ie. to ensure that the active class is added correctly if query params are present.

3. I confirmed the test without the fix produces fails - but it is always good to upload a test-only patch to prove this.

Great work morenstrat. Now I think we have a patch that should be approved.

Committed/pushed to 8.3.x and cherry-picked to 8.2.x. Thanks!