service: Include TS code module dir in .env search (#485)

* service: Include TS code module dir in .env search

* examples: Update teststand_nivisa_dmm.py to search for `.env` starting with the code module's parent directory

* tests: Fix mypy errors and last-minute rename errors

* service: Work around lack of PurePath.is_relative_to() in Python 3.8

* service: Make _get_nims_path return package dir, not __init__.py path

* service: Fix _get_caller_path() with Python >= 3.11

In Python 3.11 and later, `traceback.walk_stack(None)` skips more stack frames than in the past: python/cpython#96092

* tests: Make pytest path check less specific

Author: bkeryan

examples/nivisa_dmm_measurement/teststand_nivisa_dmm.py

@@ -12,8 +12,8 @@
 )
 from ni_measurementlink_service.session_management._types import SessionInformation
 
-# Search for the `.env` file starting with the current directory.
-_config = AutoConfig(str(pathlib.Path.cwd()))
+# Search for the `.env` file starting with this code module's parent directory.
+_config = AutoConfig(str(pathlib.Path(__file__).resolve().parent))
 _VISA_DMM_SIMULATE: bool = _config("MEASUREMENTLINK_VISA_DMM_SIMULATE", default=False, cast=bool)
 
 

examples/output_voltage_measurement/teststand_nivisa_dmm.py

@@ -12,8 +12,8 @@
 )
 from ni_measurementlink_service.session_management._types import SessionInformation
 
-# Search for the `.env` file starting with the current directory.
-_config = AutoConfig(str(pathlib.Path.cwd()))
+# Search for the `.env` file starting with this code module's parent directory.
+_config = AutoConfig(str(pathlib.Path(__file__).resolve().parent))
 _VISA_DMM_SIMULATE: bool = _config("MEASUREMENTLINK_VISA_DMM_SIMULATE", default=False, cast=bool)
 
 

ni_measurementlink_service/_configuration.py

@@ -1,12 +1,13 @@
 """MeasurementLink configuration options."""
 from __future__ import annotations
 
-import pathlib
 import sys
 from typing import TYPE_CHECKING, Any, Callable, Dict, NamedTuple, TypeVar, Union
 
 from decouple import AutoConfig, Undefined, undefined
 
+from ni_measurementlink_service._dotenvpath import get_dotenv_search_path
+
 if TYPE_CHECKING:
     if sys.version_info >= (3, 11):
         from typing import Self
@@ -16,8 +17,7 @@
 
 _PREFIX = "MEASUREMENTLINK"
 
-# Search for the `.env` file starting with the current directory.
-_config = AutoConfig(str(pathlib.Path.cwd()))
+_config = AutoConfig(str(get_dotenv_search_path()))
 
 if TYPE_CHECKING:
     # Work around decouple's lack of type hints.

ni_measurementlink_service/_dotenvpath.py

@@ -0,0 +1,68 @@
+import inspect
+import sys
+import traceback
+from pathlib import Path, PurePath
+from typing import Optional
+
+
+def get_dotenv_search_path() -> Path:
+    """Get the search path for loading the `.env` file."""
+    # Prefer to load the `.env` file from the current directory or its parents.
+    # If the current directory doesn't have a `.env` file, fall back to the
+    # script/EXE path or the TestStand code module path.
+    cwd = Path.cwd()
+    if not _has_dotenv_file(cwd):
+        if script_or_exe_path := _get_script_or_exe_path():
+            return script_or_exe_path.resolve().parent
+        if caller_path := _get_caller_path():
+            return caller_path.resolve().parent
+    return cwd
+
+
+def _has_dotenv_file(dir: Path) -> bool:
+    """Check whether the dir or its parents contains a `.env` file."""
+    return (dir / ".env").exists() or any((p / ".env").exists() for p in dir.parents)
+
+
+def _get_script_or_exe_path() -> Optional[Path]:
+    """Get the path of the top-level script or PyInstaller EXE, if possible."""
+    if getattr(sys, "frozen", False):
+        return Path(sys.executable)
+
+    main_module = sys.modules.get("__main__")
+    if main_module:
+        script_path = getattr(main_module, "__file__", "")
+        if script_path:
+            return Path(script_path)
+
+    return None
+
+
+def _get_caller_path() -> Optional[Path]:
+    """Get the path of the module calling into ni_measurementlink_service, if possible."""
+    nims_path = _get_nims_path()
+    for frame, _ in traceback.walk_stack(inspect.currentframe()):
+        if frame.f_code.co_filename:
+            module_path = Path(frame.f_code.co_filename)
+            if module_path.exists() and not _is_relative_to(module_path, nims_path):
+                return module_path
+
+    return None
+
+
+def _is_relative_to(path: PurePath, other: PurePath) -> bool:
+    if sys.version_info >= (3, 9):
+        return path.is_relative_to(other)
+    else:
+        try:
+            _ = path.relative_to(other)
+            return True
+        except ValueError:
+            return False
+
+
+def _get_nims_path() -> Path:
+    """Get the path of the ni_measurementlink_service package."""
+    nims_module = sys.modules["ni_measurementlink_service"]
+    assert nims_module.__file__ and nims_module.__file__.endswith("__init__.py")
+    return Path(nims_module.__file__).parent

tests/unit/test_dotenvpath.py

@@ -0,0 +1,34 @@
+from pathlib import Path
+
+import pytest
+
+from ni_measurementlink_service import _dotenvpath
+
+
+@pytest.mark.parametrize("dotenv_exists", [False, True])
+def test___dotenv_exists_varies___has_dotenv_file___matches_dotenv_exists(
+    dotenv_exists: bool, tmp_path: Path
+) -> None:
+    if dotenv_exists:
+        (tmp_path / ".env").write_text("")
+    subdirs = [tmp_path / "a", tmp_path / "a" / "b", tmp_path / "a" / "b" / "c"]
+    for dir in subdirs:
+        dir.mkdir()
+
+    assert _dotenvpath._has_dotenv_file(tmp_path) == dotenv_exists
+    assert all([_dotenvpath._has_dotenv_file(p) == dotenv_exists for p in subdirs])
+
+
+def test___get_caller_path___returns_this_modules_path() -> None:
+    assert _dotenvpath._get_caller_path() == Path(__file__)
+
+
+def test___get_nims_path___returns_package_dir() -> None:
+    assert _dotenvpath._get_nims_path() == Path(_dotenvpath.__file__).parent
+
+
+def test___get_script_or_exe_path___returns_pytest_path() -> None:
+    path = _dotenvpath._get_script_or_exe_path()
+
+    assert path is not None
+    assert "pytest" in path.parts or "pytest.exe" in path.parts