try with sudo

plugins/updater/tests/app-updater/.cargo/config.toml

@@ -0,0 +1,5 @@
+[target.'cfg(windows)']
+runner = "powershell -Command Start-Process -Verb runAs -FilePath"
+
+[target.x86_64-unknown-linux-gnu]
+runner = 'sudo -E'

plugins/updater/tests/app-updater/src/main.rs

@@ -27,9 +27,7 @@ fn main() {
                     let exe = tauri::utils::platform::current_exe().unwrap();
                     let dir = dunce::simplified(exe.parent().unwrap()).display();
                     if target == "nsis" {
-                        builder = builder
+                        builder = builder.installer_arg(format!("/D=\"{dir}\"",));
-                            .installer_arg("/NS")
-                            .installer_arg(format!("/D=\"{dir}\"",));
                     } else if target == "msi" {
                         builder = builder.installer_arg(format!("INSTALLDIR=\"{dir}\""));
                     }

plugins/updater/tests/app-updater/tests/update.rs

@@ -200,7 +200,7 @@ fn nsis() {
     test_update(&app, update_bundle, signature, "nsis");
 
     // cleanup the installed application
-    if std::env::var("CI").map(|v| v == "true").unwrap_or_default() {
+    if !std::env::var("CI").map(|v| v == "true").unwrap_or_default() {
         let _ = Command::new(target_dir.join("debug/uninstall.exe"))
             .arg("/S")
             .status()
@@ -230,7 +230,7 @@ fn msi() {
     test_update(&app, update_bundle, signature, "msi");
 
     // cleanup the installed application
-    if std::env::var("CI").map(|v| v == "true").unwrap_or_default() {
+    if !std::env::var("CI").map(|v| v == "true").unwrap_or_default() {
         let uninstall = target_dir.join("debug/Uninstall app-updater.lnk");
         let _ = Command::new("cmd")
             .arg("/c")