FIX: importlib_resources-related edge cases

CHANGELOG.rst

@@ -11,6 +11,7 @@ Changes
 * FIX: mitigate speed regressions introduced in 5.0.0 #376
 * FIX: Use import system to locate module file run by ``kernprof -m`` #389
 * FIX: Fixed build on Windows-ARM64 and now building wheels therefor in CI #391
+* FIX: Edge case where ``line_profiler.toml_config`` misbehaves if ``importlib.resources`` is replaced with certain versions of the ``importlib_resources`` backport #406
 
 5.0.0
 ~~~~~

line_profiler/toml_config.py

@@ -105,11 +105,26 @@ def from_default(cls, *, copy=True):
             New instance if ``copy`` is true, the global default
             instance otherwise.
         """
+        # Note: NORMALLY `importlib.resources.path()` is available on
+        # all targetted Python versions and is not deprecated, so we
+        # could've just used said function directly.
+        # However, there are edge cases in which `importlib.resources`
+        # has been superseded with `importlib_resources`, which may
+        # cause various issues (incl. `DeprecationWarning`s or even
+        # errors) dep. on the latter's version (see GitHub issue #405).
+        ir = importlib.resources
+        try:
+            ir_files, ir_as_file = ir.files, ir.as_file
+        except AttributeError:  # Python < 3.9
+            find_file = ir.path
+        else:
+            def find_file(anc, *chunks):
+                return ir_as_file(ir_files(anc).joinpath(*chunks))
+
         global _DEFAULTS
         if _DEFAULTS is None:
             package = __spec__.name.rpartition('.')[0]
-            with importlib.resources.path(package + '.rc',
-                                          'line_profiler.toml') as path:
+            with find_file(package + '.rc', 'line_profiler.toml') as path:
                 conf_dict, source = find_and_read_config_file(config=path)
             conf_dict = get_subtable(conf_dict, NAMESPACE, allow_absence=False)
             _DEFAULTS = cls(conf_dict, source, list(NAMESPACE))

tests/test_toml_config.py

@@ -2,20 +2,30 @@
 Test the handling of TOML configs.
 """
 import os
-import pathlib
+import re
+import sys
+from functools import partial
+from platform import system
+from pathlib import Path
+from shutil import which
+from subprocess import run, CompletedProcess
+from tempfile import TemporaryDirectory
+from textwrap import dedent
+from typing import Generator, Sequence, Union
+
 import pytest
-import textwrap
+
 from line_profiler.toml_config import ConfigSource
 
 
-def write_text(path: pathlib.Path, text: str, /, *args, **kwargs) -> int:
-    text = textwrap.dedent(text).strip('\n')
+def write_text(path: Path, text: str, /, *args, **kwargs) -> int:
+    text = dedent(text).strip('\n')
     return path.write_text(text, *args, **kwargs)
 
 
 @pytest.fixture(autouse=True)
 def fresh_curdir(monkeypatch: pytest.MonkeyPatch,
-                 tmp_path_factory: pytest.TempPathFactory) -> pathlib.Path:
+                 tmp_path_factory: pytest.TempPathFactory) -> Path:
     """
     Ensure that the tests start on a clean slate: they shouldn't see
     the environment variable :envvar:`LINE_PROFILER_RC`, nor should the
@@ -61,7 +71,7 @@ def test_default_config_deep_copy() -> None:
     assert column_widths is not default_2['show']['column_widths']
 
 
-def test_table_normalization(fresh_curdir: pathlib.Path) -> None:
+def test_table_normalization(fresh_curdir: Path) -> None:
     """
     Test that even if a config file misses some items (and has so extra
     ones), it is properly normalized to contain the same keys as the
@@ -86,7 +96,7 @@ def test_table_normalization(fresh_curdir: pathlib.Path) -> None:
     assert loaded.conf_dict == default_config
 
 
-def test_malformed_table(fresh_curdir: pathlib.Path) -> None:
+def test_malformed_table(fresh_curdir: Path) -> None:
     """
     Test that we get a `ValueError` when loading a malformed table with a
     non-subtable value taking the place of a supposed subtable.
@@ -103,7 +113,7 @@ def test_malformed_table(fresh_curdir: pathlib.Path) -> None:
 
 
 def test_config_lookup_hierarchy(monkeypatch: pytest.MonkeyPatch,
-                                 fresh_curdir: pathlib.Path) -> None:
+                                 fresh_curdir: Path) -> None:
     """
     Test the hierarchy according to which we load config files.
     """
@@ -145,3 +155,156 @@ def test_config_lookup_hierarchy(monkeypatch: pytest.MonkeyPatch,
     # (`None`), and `False` to disabling all lookup
     assert ConfigSource.from_config(True).path.samefile(high_priority)
     assert ConfigSource.from_config(False).path.samefile(default)
+
+
+########################################################################
+#           START: edge-case test for `importlib_resources`            #
+########################################################################
+
+# XXX: this addresses an edge case where `importlib.resources` have been
+# superseded by `importlib_resources` during runtime.
+# Do we REALLY need such an involved (and slow) test for something we
+# don't otherwise interact with?
+
+
+@pytest.fixture(scope='module')
+def _venv() -> Generator[Path, None, None]:
+    """
+    A MODULE-scoped fixture for a venv in which `line_profiler` has been
+    separately installed.
+    """
+    with TemporaryDirectory() as tmpdir_:
+        tmpdir = Path(tmpdir_)
+        # Build the venv
+        venv = tmpdir / 'venv'
+        cmd = [sys.executable, '-m', 'venv', venv]
+        run_proc(cmd).check_returncode()
+        # Install `line_profiler` in the venv
+        # (somehow `--system-site-packages` doesn't work)
+        source = Path(__file__).parent.parent
+        install = run_pip_in_venv('install', [source], tmpdir, venv)
+        install.check_returncode()
+        yield venv
+
+
+@pytest.fixture
+def venv(tmp_path: Path, _venv: Path) -> Generator[Path, None, None]:
+    """
+    A FUNCTION-scoped fixture for a venv in which:
+    - `line_profiler` has been separately installed, and
+    - `importlib-resources` is uninstalled after each test.
+
+    Yields:
+        venv (pathlib.Path):
+            The temporary venv directory.
+    """
+    try:
+        yield _venv
+    finally:
+        run_pip_in_venv('uninstall', ['--yes', 'importlib-resources'],
+                        tmp_path, _venv)
+
+
+def run_proc(cmd: Sequence[Union[str, Path]], /, **kwargs) -> CompletedProcess:
+    """Convenience wrapper around `subprocess.run()`."""
+    kwargs.update(text=True, capture_output=True)
+    proc = run([str(arg) for arg in cmd], **kwargs)
+    print(proc.stderr, end='', file=sys.stderr)
+    print(proc.stdout, end='')
+    return proc
+
+
+def run_python_in_venv(args: Sequence[Union[str, Path]],
+                       tmpdir: Path,
+                       venv: Path) -> CompletedProcess:
+    """Run `$ python *args` in `venv`."""
+    if 'windows' in system().lower():  # Use PowerShell on Windows
+        shell = which('PowerShell.exe')
+        assert shell is not None
+        script_file = tmpdir / 'script.ps1'
+        write_text(script_file, """
+        $Activate, $Remainder = $args
+        Invoke-Expression $Activate
+        python @Remainder
+        """)
+        base_cmd = [shell, '-NonInteractive', '-File', script_file,
+                    venv / 'Scripts' / 'Activate.ps1']
+    else:  # Use Bash otherwise (*nix etc.)
+        shell = which('bash')
+        assert shell is not None
+        script_file = tmpdir / 'script.bsh'
+        write_text(script_file, """
+        activate="$1"; shift
+        source "${activate}"
+        python "${@}"
+        """)
+        base_cmd = [shell, script_file, venv / 'bin' / 'activate']
+
+    return run_proc(base_cmd + list(args))
+
+
+def run_pip_in_venv(
+        subcmd: str, args: Union[Sequence[Union[str, Path]], None] = None, /,
+        *a, **k) -> CompletedProcess:
+    """Run `$ pip subcmd *args` in `venv`."""
+    cmd = ['-m', 'pip', subcmd, '--require-virtualenv', *(args or [])]
+    return run_python_in_venv(cmd, *a, **k)
+
+
+@pytest.mark.parametrize(
+    'version',
+    [False,           # Don't use `importlib_resources`
+     True,            # Newest (`path()` imported from stdlib)
+     '< 6',           # Legacy (defines `path()` but deprecates it)
+     '>= 6, < 6.4'])  # Corner case (`path()` unavailable)
+def test_backported_importlib_resources(
+        tmp_path: Path, venv: Path, version: Union[str, bool]) -> None:
+    """
+    Test that the location of the installed TOML config file by
+    `line_profiler.toml_config` works even when `importlib.resources`
+    has been replaced by `importlib_resources` during runtime (see
+    GitHub issue #405).
+    """
+    run_python = partial(run_python_in_venv, tmpdir=tmp_path, venv=venv)
+    run_pip = partial(run_pip_in_venv, tmpdir=tmp_path, venv=venv)
+
+    # Install the required `importlib_resources` version
+    if version:
+        ir = 'importlib_resources'
+        if isinstance(version, str):
+            ir = f'{ir} {version}'
+
+        run_pip('install', ['--upgrade', ir]).check_returncode()
+    run_pip('list')
+
+    # Run python code which substitutes `importlib.resources` with
+    # `importlib_resources` before importing `line_profiler` and see
+    # what happens
+    python_script = tmp_path / 'script.py'
+    if version:
+        preamble = dedent("""
+    import importlib
+    import importlib_resources as _ir
+    import sys
+
+    importlib.resources = sys.modules['importlib.resources'] = _ir
+    del _ir
+        """)
+    else:
+        preamble = ''
+    sanity_check = dedent("""
+    from line_profiler.toml_config import ConfigSource
+
+
+    print(ConfigSource.from_default())
+    """)
+    write_text(python_script, f'{preamble}\n\n{sanity_check}')
+    proc = run_python(['-W', 'always::DeprecationWarning', python_script])
+    proc.check_returncode()
+    assert not re.search('DeprecationWarning.*importlib[-_]?resources',
+                         proc.stderr), proc.stderr
+
+
+########################################################################
+#            END: edge-case test for `importlib_resources`             #
+########################################################################