[GH 13837] Remove trailing slash from $XDG_RUNTIME_DIR (#13929)

* [GH 13837] Remove trailing slash from $XDG_RUNTIME_DIR

* pr feedback

---------

Co-authored-by: Ben Hillis <benhill@ntdev.microsoft.com>

Author: benhillis

src/linux/init/init.cpp

@@ -690,7 +690,7 @@ try
         }
 
         Common->Environment.AddVariable("DBUS_SESSION_BUS_ADDRESS", std::format("unix:path=/run/user/{}/bus", PasswordEntry->pw_uid));
-        Common->Environment.AddVariable(XDG_RUNTIME_DIR_ENV, std::format("/run/user/{}/", PasswordEntry->pw_uid));
+        Common->Environment.AddVariable(XDG_RUNTIME_DIR_ENV, std::format("/run/user/{}", PasswordEntry->pw_uid));
     }
 
     //

test/windows/UnitTests.cpp

@@ -268,17 +268,24 @@ class UnitTests
         {
             validateUserSession();
 
-            auto [out, err] = LxsstuLaunchWslAndCaptureOutput(std::format(L"echo $DISPLAY", LXSST_TEST_USERNAME));
+            auto [out, err] = LxsstuLaunchWslAndCaptureOutput(std::format(L"--user {} echo $DISPLAY", LXSST_TEST_USERNAME));
             VERIFY_ARE_EQUAL(out, L"\n");
+
+            // N.B. The XDG_RUNTIME_DIR variable is always set by init even if gui apps are disabled.
+            std::tie(out, err) = LxsstuLaunchWslAndCaptureOutput(std::format(L"--user {} echo $XDG_RUNTIME_DIR", LXSST_TEST_USERNAME));
+            VERIFY_ARE_EQUAL(out, std::format(L"/run/user/{}\n", TestUid));
         }
 
         // Validate user sessions state with gui apps enabled.
         {
             WslConfigChange config(LxssGenerateTestConfig({.guiApplications = true}));
 
             validateUserSession();
-            auto [out, err] = LxsstuLaunchWslAndCaptureOutput(std::format(L"echo $DISPLAY", LXSST_TEST_USERNAME));
+            auto [out, err] = LxsstuLaunchWslAndCaptureOutput(std::format(L"--user {} echo $DISPLAY", LXSST_TEST_USERNAME));
             VERIFY_ARE_EQUAL(out, L":0\n");
+
+            std::tie(out, err) = LxsstuLaunchWslAndCaptureOutput(std::format(L"--user {} echo $XDG_RUNTIME_DIR", LXSST_TEST_USERNAME));
+            VERIFY_ARE_EQUAL(out, std::format(L"/run/user/{}\n", TestUid));
         }
 
         // Create a 'broken' /run/user and validate that the warning is correctly displayed.