: python/tests/test_actors.py: more contextmgr improvements

Summary: this refactors the python-side config helpers to make Runtime-layer overrides explicit and reversible, replaces the previous "restore from snapshot" approach with a clearer model that writes into the Runtime layer on entry and clears it on exit, and exposes a Rust-backed `clear()` to support that. the main functional change is adding `configured_with_redirected_stdio()`, which composes configuration overrides with stdio redirection in a single context manager so the tests don't need nested with blocks. all affected tests are updated to use the combined form, but the underlying logging behaviour is unchanged.

Differential Revision: D87795973

Author: shayne-fletcher

hyperactor/src/config/global.rs

@@ -524,8 +524,7 @@ pub fn create_or_merge(source: Source, attrs: Attrs) {
 /// contribute to resolution in [`get`], [`get_cloned`], or
 /// [`attrs`]. Defaults and any remaining layers continue to apply
 /// in their normal priority order.
-#[allow(dead_code)]
-pub(crate) fn clear(source: Source) {
+pub fn clear(source: Source) {
     let mut g = LAYERS.write().unwrap();
     g.ordered.retain(|l| layer_source(l) != source);
 }

monarch_hyperactor/src/config.rs

@@ -211,6 +211,18 @@ fn configure(py: Python<'_>, kwargs: Option<HashMap<String, PyObject>>) -> PyRes
     Ok(())
 }
 
+/// Clear runtime configuration overrides.
+///
+/// This removes all entries from the Runtime config layer for this
+/// process (e.g. set via test fixtures or ad-hoc tweaking), without
+/// affecting any other layers (env, file, test overrides, or built-in
+/// defaults).
+#[pyfunction]
+fn clear(_py: Python<'_>) -> PyResult<()> {
+    hyperactor::config::global::clear(Source::Runtime);
+    Ok(())
+}
+
 /// For all attribute keys whose `@meta(CONFIG = ConfigAttr { py_name:
 /// Some(...), .. })` specifies a kwarg name, return the current
 /// associated value in the global config. Keys with no value in the
@@ -252,5 +264,12 @@ pub fn register_python_bindings(module: &Bound<'_, PyModule>) -> PyResult<()> {
     )?;
     module.add_function(get_configuration)?;
 
+    let clear = wrap_pyfunction!(clear, module)?;
+    clear.setattr(
+        "__module__",
+        "monarch._rust_bindings.monarch_hyperactor.config",
+    )?;
+    module.add_function(clear)?;
+
     Ok(())
 }

python/monarch/_rust_bindings/monarch_hyperactor/config.pyi

@@ -28,5 +28,33 @@ def configure(
     enable_log_forwarding: bool = False,
     enable_file_capture: bool = False,
     tail_log_lines: int = 0,
-) -> None: ...
-def get_configuration() -> Dict[str, Any]: ...
+) -> None:
+    """Configure Hyperactor runtime defaults for this process.
+
+    This updates the **runtime** configuration layer from Python,
+    setting the default channel transport and optional logging
+    behaviour (forwarding, file capture, and how many lines to tail).
+    Environment-based settings remain in effect and are merged with
+    these runtime overrides.
+
+    """
+    ...
+
+def clear() -> None:
+    """Clear runtime configuration overrides applied from Python.
+
+    This resets the **runtime** configuration layer back to its
+    baseline, undoing any overrides set via this module during the
+    lifetime of the process.
+
+    """
+    ...
+
+def get_configuration() -> Dict[str, Any]:
+    """Return a snapshot of the current Hyperactor configuration.
+
+    The result is a plain dictionary view of the merged configuration
+    (defaults plus any overrides from environment or Python), useful
+    for debugging and tests.
+    """
+    ...