test: add a packaging test so make test cannot pass on an empty suite

pytest.ini

@@ -1,14 +1,25 @@
 [pytest]
 testpaths = tests
-# Enable live logs on console
-log_cli = true
+# Make the synced template test-suite importable (test_utils, api/, sync/, ...)
+# without each conftest manipulating sys.path at import time. Resolved relative
+# to rootdir; harmless when .rhiza/tests is absent.
+pythonpath = .rhiza/tests
+# Disable live logs on console by default (opt in with: pytest -o log_cli=true --log-cli-level=DEBUG)
+log_cli = false
 # Show DEBUG+ messages
 log_cli_level = DEBUG
 log_cli_format = %(asctime)s %(levelname)s %(name)s: %(message)s
 log_cli_date_format = %H:%M:%S
 # Show extra summary info for skipped/failed tests
 addopts = -ra
 timeout = 60
+# Treat the class-scoped-instance-method fixture deprecation as an error so it
+# cannot silently regress. Matched by message rather than by warning category:
+# the category name is version-specific (PytestRemovedIn9Warning vs ...In10Warning)
+# and referencing a missing class breaks `--resolution lowest-direct` runs at
+# parse time. Third-party DeprecationWarnings stay non-fatal.
+filterwarnings =
+    error:Class-scoped fixture defined as instance method is deprecated
 # Register custom markers
 markers =
     stress: marks tests as stress tests (deselect with '-m "not stress"')

tests/test_rhiza_packaging.py

@@ -0,0 +1,97 @@
+"""The first test a freshly synced Python project has.
+
+This file flows down via a SYNC action from the jebel-quant/rhiza repository
+(https://github.com/jebel-quant/rhiza).
+
+**Why it exists.** Two reasons, and the second is the one that is easy to lose.
+
+It checks a real invariant: that the version the project *declares* in
+``pyproject.toml`` is the version actually installed into the environment. Those drift
+apart more often than anything else on a fresh checkout — an editable install left over
+from a rename, a `uv sync` that never ran, a package directory the build backend is not
+configured to pick up. Each shows up here as a mismatch rather than as a confusing
+ImportError three files later.
+
+And it is the only test a freshly synced project has. ``make test`` searches
+``TESTS_FOLDER`` for ``test_*.py``/``*_test.py``, and finding none it prints a warning
+and **exits 0** — so a new repo passed ``make test``, and therefore ``make all``, while
+measuring nothing (#1476). That was the third instance of one pattern: Go had it until
+``go-core`` shipped ``internal/version/version_test.go`` (#1467), and ``rhiza-test`` had
+it until the ``.rhiza/tests`` suite was actually delivered to every layer (#1469). Rust
+never did, because ``cargo init --lib`` leaves an ``it_works`` test behind.
+
+Writing your own tests alongside this is the point. Deleting it and shipping nothing
+else puts the vacuum back.
+
+**Why not simply fail when no tests exist?** Because that turns ``make all`` red on the
+output of ``/rhiza:init``, before the author has written a line. The warning branch is
+deliberate; what it needed was something to find.
+
+Deliberately self-contained: it uses no fixtures, because this lives in *your* ``tests/``
+directory and must not depend on the ``conftest.py`` that ships with ``.rhiza/tests``.
+"""
+
+from __future__ import annotations
+
+import tomllib
+from importlib.metadata import PackageNotFoundError
+from importlib.metadata import version as installed_version
+from pathlib import Path
+
+import pytest
+
+# tests/ sits at the project root, so the parent of this file's directory is the root.
+#
+# `.absolute()`, never `.resolve()`. In a synced project the difference is nil, but in
+# rhiza's own repository this file is a *symlink* into `bundles/python-core/tests/`, and
+# `.resolve()` follows it — making the "project root" come out as `bundles/python-core`,
+# which has no pyproject.toml. The suite then skips for a plausible-looking wrong reason
+# instead of running. `.rhiza/tests/conftest.py` avoids the same trap the same way.
+_ROOT = Path(__file__).absolute().parent.parent
+
+
+def _project_table() -> dict:
+    """Return the ``[project]`` table from pyproject.toml, skipping when unusable.
+
+    Returns:
+        The parsed ``[project]`` table.
+    """
+    pyproject = _ROOT / "pyproject.toml"
+    if not pyproject.is_file():
+        pytest.skip("no pyproject.toml at the project root")
+    with pyproject.open("rb") as handle:
+        table = tomllib.load(handle).get("project")
+    if not isinstance(table, dict):
+        pytest.skip("pyproject.toml declares no [project] table")
+    return table
+
+
+def test_the_installed_version_matches_pyproject() -> None:
+    """The distribution installed in the environment must match the declared version.
+
+    Skips rather than fails when the project is not installed as a distribution at all —
+    a ``uv`` *virtual* project (no ``[build-system]``, ``source = {{ virtual = "." }}`` in
+    the lockfile) has no metadata to read, and rhiza's own repository is one. That is a
+    real configuration, not a broken one, so it is not this test's business.
+    """
+    project = _project_table()
+
+    name = project.get("name")
+    if not isinstance(name, str) or not name.strip():
+        pytest.skip("[project].name is missing or not a plain string")
+
+    declared = project.get("version")
+    if not isinstance(declared, str):
+        pytest.skip("[project].version is dynamic — there is no static value to compare")
+
+    try:
+        found = installed_version(name)
+    except PackageNotFoundError:
+        pytest.skip(f"{name!r} is not installed as a distribution (a virtual project has no metadata)")
+
+    assert found == declared, (
+        f"pyproject.toml declares version {declared!r} but the installed {name!r} reports "
+        f"{found!r}. The environment is stale or the build backend is picking up a different "
+        f"tree — re-run `make install`, and check [build-system] and the packages it is told "
+        f"to include if that does not fix it."
+    )