test: switch zero-dep install tests to uv venv (#14)

stdlib `venv.create(..., with_pip=True)` calls `python -m ensurepip`
inside the new venv, which aborts with SIGABRT on cpython 3.11.14
macOS-aarch64. None of the 5 tests in test_zero_dep_install.py could
run as a result.

Switch to `uv venv` + `uv pip install --python <venv-python>`. uv has
its own resolver and does not depend on ensurepip, so it works on
this Python build, runs faster, and matches the rest of the project's
tooling. Skip the suite (rather than fail) on machines without uv.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: silversurfer562

tests/test_zero_dep_install.py

@@ -9,42 +9,60 @@
 
 This guards the architectural contract documented in ``tech.md``
 ADR-002. Marked ``slow`` because it creates a real venv.
+
+Uses ``uv venv`` + ``uv pip`` rather than stdlib ``venv``/``pip`` because
+``ensurepip`` aborts on some Python builds (observed on cpython 3.11.14
+macOS-aarch64).
 """
 
 from __future__ import annotations
 
+import shutil
 import subprocess
 import sys
-import venv
 from pathlib import Path
 
 import pytest
 
 REPO_ROOT = Path(__file__).resolve().parent.parent
 
+_UV = shutil.which("uv")
 
-@pytest.mark.slow
-@pytest.mark.skipif(
-    sys.platform.startswith("win"),
-    reason="venv layout differs on Windows; covered on Linux/macOS",
+_requires_uv = pytest.mark.skipif(
+    _UV is None,
+    reason="uv is required to build the isolated test venv (stdlib ensurepip is unreliable)",
 )
-def test_attune_help_imports_without_authoring_extra(tmp_path: Path) -> None:
-    venv_dir = tmp_path / "venv"
-    venv.create(venv_dir, with_pip=True)
-    py = venv_dir / "bin" / "python"
-    pip = venv_dir / "bin" / "pip"
 
+
+def _make_venv(venv_dir: Path) -> Path:
+    """Create a venv at ``venv_dir`` via ``uv venv`` and return its python."""
     subprocess.run(
-        [str(pip), "install", "--quiet", "python-frontmatter"],
+        [_UV, "venv", "--quiet", str(venv_dir)],
         check=True,
         capture_output=True,
     )
+    return venv_dir / "bin" / "python"
+
+
+def _install(py: Path, *args: str) -> None:
     subprocess.run(
-        [str(pip), "install", "--quiet", "--no-deps", "-e", str(REPO_ROOT)],
+        [_UV, "pip", "install", "--quiet", "--python", str(py), *args],
         check=True,
         capture_output=True,
     )
 
+
+@pytest.mark.slow
+@_requires_uv
+@pytest.mark.skipif(
+    sys.platform.startswith("win"),
+    reason="venv layout differs on Windows; covered on Linux/macOS",
+)
+def test_attune_help_imports_without_authoring_extra(tmp_path: Path) -> None:
+    py = _make_venv(tmp_path / "venv")
+    _install(py, "python-frontmatter")
+    _install(py, "--no-deps", "-e", str(REPO_ROOT))
+
     base = subprocess.run(
         [str(py), "-c", "import attune_help; print('ok')"],
         capture_output=True,
@@ -55,6 +73,7 @@ def test_attune_help_imports_without_authoring_extra(tmp_path: Path) -> None:
 
 
 @pytest.mark.slow
+@_requires_uv
 @pytest.mark.skipif(
     sys.platform.startswith("win"),
     reason="venv layout differs on Windows; covered on Linux/macOS",
@@ -69,21 +88,9 @@ def test_attune_help_imports_without_authoring_extra(tmp_path: Path) -> None:
     ],
 )
 def test_shim_imports_fail_helpfully_without_authoring(tmp_path: Path, shim_module: str) -> None:
-    venv_dir = tmp_path / "venv"
-    venv.create(venv_dir, with_pip=True)
-    py = venv_dir / "bin" / "python"
-    pip = venv_dir / "bin" / "pip"
-
-    subprocess.run(
-        [str(pip), "install", "--quiet", "python-frontmatter"],
-        check=True,
-        capture_output=True,
-    )
-    subprocess.run(
-        [str(pip), "install", "--quiet", "--no-deps", "-e", str(REPO_ROOT)],
-        check=True,
-        capture_output=True,
-    )
+    py = _make_venv(tmp_path / "venv")
+    _install(py, "python-frontmatter")
+    _install(py, "--no-deps", "-e", str(REPO_ROOT))
 
     result = subprocess.run(
         [str(py), "-c", f"import {shim_module}"],