fix(test): Use a mutex to prevent race conditions between tests relying on KUBECONFIG env var

harmony/src/domain/topology/k8s_anywhere/k8s_anywhere.rs

@@ -1222,9 +1222,11 @@ fn extract_base_domain(host: &str) -> Option<String> {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::sync::Mutex;
     use std::sync::atomic::{AtomicUsize, Ordering};
 
     static TEST_COUNTER: AtomicUsize = AtomicUsize::new(0);
+    static ENV_LOCK: Mutex<()> = Mutex::new(());
 
     /// Sets environment variables with unique names to avoid concurrency issues between tests.
     /// Returns the names of the (config_var, profile_var) used.
@@ -1289,6 +1291,7 @@ mod tests {
 
     #[test]
     fn test_remote_k8s_from_env_var_only_context() {
+        let _lock = ENV_LOCK.lock().unwrap_or_else(|e| e.into_inner());
         run_in_isolated_env(|| {
             unsafe {
                 std::env::remove_var("KUBECONFIG");
@@ -1305,6 +1308,7 @@ mod tests {
 
     #[test]
     fn test_remote_k8s_from_env_var_unknown_key_trim() {
+        let _lock = ENV_LOCK.lock().unwrap_or_else(|e| e.into_inner());
         run_in_isolated_env(|| {
             unsafe {
                 std::env::remove_var("KUBECONFIG");
@@ -1324,6 +1328,7 @@ mod tests {
 
     #[test]
     fn test_remote_k8s_from_env_var_empty_malformed() {
+        let _lock = ENV_LOCK.lock().unwrap_or_else(|e| e.into_inner());
         run_in_isolated_env(|| {
             unsafe {
                 std::env::remove_var("KUBECONFIG");
@@ -1341,6 +1346,7 @@ mod tests {
 
     #[test]
     fn test_remote_k8s_from_env_var_kubeconfig_fallback() {
+        let _lock = ENV_LOCK.lock().unwrap_or_else(|e| e.into_inner());
         run_in_isolated_env(|| {
             unsafe {
                 std::env::set_var("KUBECONFIG", "/fallback/path");
@@ -1357,6 +1363,7 @@ mod tests {
 
     #[test]
     fn test_remote_k8s_from_env_var_kubeconfig_no_fallback_if_provided() {
+        let _lock = ENV_LOCK.lock().unwrap_or_else(|e| e.into_inner());
         run_in_isolated_env(|| {
             unsafe {
                 std::env::set_var("KUBECONFIG", "/fallback/path");