test: replace ventored chdir context manager with contextlib

Our docker container uses Python 3.12 these days, so follow the comment
the says "once we upgrade past 3.11, use the stdlib".

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

tests/framework/ab_test.py

@@ -21,7 +21,6 @@
 of both invocations is the same, the test passes (with us being alerted to this situtation via a special pipeline that
 does not block PRs). If not, it fails, preventing PRs from introducing new vulnerable dependencies.
 """
-import contextlib
 import os
 import statistics
 from pathlib import Path
@@ -249,17 +248,3 @@ def git_clone(clone_path, commitish):
         )
         utils.check_output(f"git branch -D {branch_name}")
     return clone_path
-
-
-# Once we upgrade to python 3.11, this will be in contextlib:
-# https://docs.python.org/3/library/contextlib.html#contextlib.chdir
-@contextlib.contextmanager
-def chdir(to):
-    """Context manager that temporarily `chdir`s to the specified path"""
-    cur = os.getcwd()
-
-    try:
-        os.chdir(to)
-        yield
-    finally:
-        os.chdir(cur)

tests/integration_tests/performance/test_benchmarks.py

@@ -1,6 +1,7 @@
 # Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 # SPDX-License-Identifier: Apache-2.0
 """Optional benchmarks-do-not-regress test"""
+import contextlib
 import json
 import logging
 import platform
@@ -10,7 +11,7 @@
 import pytest
 
 from framework import utils
-from framework.ab_test import chdir, git_ab_test
+from framework.ab_test import git_ab_test
 from host_tools.cargo_build import cargo
 
 LOGGER = logging.getLogger(__name__)
@@ -32,7 +33,7 @@ def run_criterion(firecracker_checkout: Path, is_a: bool) -> Path:
     """
     baseline_name = "a_baseline" if is_a else "b_baseline"
 
-    with chdir(firecracker_checkout):
+    with contextlib.chdir(firecracker_checkout):
         # Passing --message-format json to cargo tells it to print its log in a json format. At the end, instead of the
         # usual "placed executable <...> at <...>" we'll get a json object with an 'executable' key, from which we
         # extract the path to the compiled benchmark binary.