Struct EnvGuard 

pub struct EnvGuard { /* private fields */ }

Holds the process’s environment lock and restores every variable it touched when dropped — including back to absent.

Implementations

impl EnvGuard

pub fn hold() -> Self

Take the lock without changing anything — for a test that only needs to be alone with the environment, or that will set_var later.

pub fn set<K, V>(vars: impl IntoIterator<Item = (K, V)>) -> Self

where K: AsRef<OsStr>, V: AsRef<OsStr>,

Take the lock and set these variables.

pub fn unset<K: AsRef<OsStr>>(vars: impl IntoIterator<Item = K>) -> Self

Take the lock and remove these variables.

pub fn set_var<K: AsRef<OsStr>, V: AsRef<OsStr>>( &mut self, key: K, value: V, ) -> &mut Self

Set one variable inside this guard’s critical section.

pub fn unset_var<K: AsRef<OsStr>>(&mut self, key: K) -> &mut Self

Remove one variable inside this guard’s critical section.

pub fn track_var<K: AsRef<OsStr>>(&mut self, key: K) -> &mut Self

Restore this variable when the guard drops, without changing it now.

For a variable the test does not set but the code under test does. Some production paths use the environment as a hidden parameter and do not put it back — deep_research::provision sets MUR_HOME for the helpers it calls and says so in its own # Concurrency note. A test calling that leaks the value to every later test in the process, and no lock can help: the leak is not a race. Run the suite with --test-threads=1 and it still happens, which is how this was found.

Trait Implementations

impl Drop for EnvGuard

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.