test: preserve native server coverage profiles (Refs #529)

Keep LLVM_PROFILE_FILE in isolated PET subprocess environments so normal EOF shutdown writes profiles into the coverage collector instead of untracked default files. Preserve fixture overrides and minimal environment isolation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: karthiknadig

crates/pet/tests/jsonrpc_client.rs

@@ -20,6 +20,21 @@ static REQUEST_ID: AtomicU32 = AtomicU32::new(1);
 
 const DEFAULT_REQUEST_TIMEOUT: Duration = Duration::from_secs(30);
 
+pub(crate) fn configure_isolated_pet_environment(command: &mut Command) {
+    command.env_clear().env("PATH", "");
+
+    if let Some(value) = std::env::var_os("LLVM_PROFILE_FILE") {
+        command.env("LLVM_PROFILE_FILE", value);
+    }
+
+    #[cfg(windows)]
+    for name in ["SYSTEMROOT", "SYSTEMDRIVE"] {
+        if let Some(value) = std::env::var_os(name) {
+            command.env(name, value);
+        }
+    }
+}
+
 #[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
 #[serde(rename_all = "camelCase")]
 pub struct RefreshResult {
@@ -121,19 +136,11 @@ impl PetJsonRpcClient {
         cmd.arg("server")
             .stdin(Stdio::piped())
             .stdout(Stdio::piped())
-            .stderr(Stdio::piped())
-            // Clear all inherited env vars to prevent host-specific tool
-            // configuration from leaking into the test environment, then
-            // restore only the minimum required for the OS to function.
-            .env_clear()
-            .env("PATH", "")
-            .envs(environment.iter().copied());
-        #[cfg(windows)]
-        for name in ["SYSTEMROOT", "SYSTEMDRIVE"] {
-            if let Some(value) = std::env::var_os(name) {
-                cmd.env(name, value);
-            }
-        }
+            .stderr(Stdio::piped());
+        configure_isolated_pet_environment(&mut cmd);
+        // Explicit fixture variables take precedence over the runner values
+        // retained by the isolated environment.
+        cmd.envs(environment.iter().copied());
         let mut process = cmd
             .spawn()
             .map_err(|e| format!("Failed to spawn pet server: {e}"))?;

crates/pet/tests/jsonrpc_server_test.rs

@@ -30,15 +30,8 @@ impl RawRpcClient {
             .arg("server")
             .stdin(Stdio::piped())
             .stdout(Stdio::piped())
-            .stderr(Stdio::inherit())
-            .env_clear()
-            .env("PATH", "");
-        #[cfg(windows)]
-        for name in ["SYSTEMROOT", "SYSTEMDRIVE"] {
-            if let Some(value) = std::env::var_os(name) {
-                command.env(name, value);
-            }
-        }
+            .stderr(Stdio::inherit());
+        jsonrpc_client::configure_isolated_pet_environment(&mut command);
         let mut child = command.spawn().expect("raw fixture must spawn PET");
         let stdout = child.stdout.take().expect("PET stdout must be piped");
         let (sender, responses) = mpsc::channel();
@@ -516,15 +509,8 @@ impl ShutdownFixture {
             .arg("server")
             .stdin(Stdio::piped())
             .stdout(Stdio::piped())
-            .stderr(Stdio::piped())
-            .env_clear()
-            .env("PATH", "");
-        #[cfg(windows)]
-        for name in ["SYSTEMROOT", "SYSTEMDRIVE"] {
-            if let Some(value) = std::env::var_os(name) {
-                command.env(name, value);
-            }
-        }
+            .stderr(Stdio::piped());
+        jsonrpc_client::configure_isolated_pet_environment(&mut command);
         Self {
             child: command.spawn().expect("shutdown fixture must spawn PET"),
         }