feat(testing.pytest): add subprocess decorator

src/byteb4rb1e/utils/testing/pytest/__init__.py

@@ -0,0 +1,14 @@
+import os
+from pathlib import Path
+from typing import Tuple
+
+
+def get_current_test() -> Tuple[Path, str]:
+    current_test_env = os.getenv("PYTEST_CURRENT_TEST")
+    if current_test_env is None:
+        raise RuntimeError("PYTEST_CURRENT_TEST not set. Must be run under pytest.")
+
+    suite_path, case_name = current_test_env.split('::', 1)
+    case_name = case_name.split(' ', 1)[0]
+    return Path(suite_path).resolve(), case_name
+

src/byteb4rb1e/utils/testing/pytest/decorators.py

@@ -0,0 +1,47 @@
+from functools import wraps
+from pathlib import Path
+import os
+import subprocess
+import sys
+
+from byteb4rb1e.utils.testing.pytest import get_current_test
+
+
+def run_in_subprocess_once():
+    """
+    A decorator that reruns th test in a subprocess if not already inside one.
+    Requires pytest to be installed and test to be run by pytest.
+
+    For what? Anything that can't be done in a thread-safe manner, e.g. modifying PYTHON_PATH
+    """
+    def decorator(test_func):
+        @wraps(test_func)
+        def wrapper(*args, **kwargs):
+            if os.environ.get("XPYTEST_INSIDE_SUBPROCESS") == "1":
+                return test_func(*args, **kwargs)
+
+            suite_path, case_name = get_current_test()
+
+            cmd = [
+                sys.executable,
+                "-m", "pytest",
+                f"{suite_path}::{case_name}",
+            ] 
+
+            result = subprocess.run(
+                cmd,
+                env={**os.environ, "XPYTEST_INSIDE_SUBPROCESS": "1"},
+                capture_output=True,
+                text=True,
+            )
+
+            if result.returncode != 0:
+                print(' '.join(cmd))
+                print("==== Subprocess stdout ====")
+                print(result.stdout)
+                print("==== Subprocess stderr ====")
+                print(result.stderr)
+                raise AssertionError(f"Subprocess test failed with exit code {result.returncode}")
+        return wrapper
+    return decorator
+

src/byteb4rb1e/utils/testing/pytest/fixtures.py

@@ -4,11 +4,11 @@ from typing import Tuple
 
 import pytest
 
+from byteb4rb1e.utils.testing.pytest import get_current_test
+
 
 @pytest.fixture
 def current_test() -> Tuple[Path, str]:
     """
     """
-    suite_path, case_name = os.getenv('PYTEST_CURRENT_TEST').split('::', 1)
-    case_name = case_name.split(' ', 1)[0]
-    return Path(suite_path).resolve(), case_name
+    return get_current_test()