Fix ETXTBSY flake in hatch version-gate test

crates/socket-patch-core/src/utils/process.rs

@@ -340,7 +340,7 @@ fn run_resolved_within(
 }
 
 #[cfg(test)]
-mod tests {
+pub(crate) mod tests {
     use super::*;
 
     /// Confirm the real runner returns Some for a tiny command we
@@ -553,7 +553,7 @@ mod tests {
     /// not a property of the shim, so retry only that error, briefly — the
     /// same pattern as `sanity_exec` and the CLI's `exec_freshly_written`.
     #[cfg(unix)]
-    fn output_of_fresh_shim(make: impl Fn() -> Command) -> Output {
+    pub(crate) fn output_of_fresh_shim(make: impl Fn() -> Command) -> Output {
         let deadline = Instant::now() + Duration::from_secs(10);
         loop {
             match make().output() {

crates/socket-patch-core/src/vendor/pypi_hatch.rs

@@ -1088,6 +1088,15 @@ mod tests {
 
     /// An executable `hatch` script in `dir` that touches `marker` and prints
     /// a Hatch version banner that passes the >=1.2 gate.
+    ///
+    /// The probe folds a spawn error into the "too old" refusal, so the
+    /// first exec of a freshly written script must not happen there: a
+    /// sibling test thread that forks while `fs::write` holds the file open
+    /// keeps a write fd until its own exec, and exec'ing the script in that
+    /// window fails with ETXTBSY. Exec it once here, tolerating only that
+    /// error; after one exec succeeds no process holds a write fd and none
+    /// can gain one, so the probe's spawn can't race. This run's `marker` is
+    /// removed so the marker records only the probe's run.
     #[cfg(unix)]
     fn fake_hatch(dir: &Path, marker: &Path) {
         use std::os::unix::fs::PermissionsExt;
@@ -1101,6 +1110,11 @@ mod tests {
         )
         .unwrap();
         std::fs::set_permissions(&script, std::fs::Permissions::from_mode(0o755)).unwrap();
+        let settle = crate::utils::process::tests::output_of_fresh_shim(|| {
+            std::process::Command::new(&script)
+        });
+        assert!(settle.status.success(), "fake hatch: {settle:?}");
+        std::fs::remove_file(marker).unwrap();
     }
 
     #[cfg(unix)]