fix: match v* when extracting a zarr version from git tags (#3994)

* fix: match v* when extracting a zarr version from git tags

* test: add test that checks immunity of pyproject.toml-defined git describe invocation against weird tags

* test: use simpler test

Author: d-v-b

pyproject.toml

@@ -148,6 +148,12 @@ omit = [
 
 [tool.hatch]
 version.source = "vcs"
+# Only consider zarr-python's own `v*` tags when deriving the version. Without
+# this filter `git describe` matches the most recent tag of any shape,
+# including the `zarr_metadata-v*` tags used to release the zarr-metadata
+# subpackage — which would make a from-source build report a `0.2.x` version
+# instead of `3.x`.
+version.raw-options = { git_describe_command = "git describe --dirty --tags --long --match v*" }
 
 [tool.hatch.build]
 hooks.vcs.version-file = "src/zarr/_version.py"

tests/test_version_derivation.py

@@ -0,0 +1,34 @@
+"""Sanity check that ``zarr.__version__`` looks like a v3-or-newer release.
+
+Background: zarr-python derives its version from ``git describe`` via
+hatch-vcs. The repo also publishes a separate ``zarr-metadata`` subpackage
+that uses ``zarr_metadata-v*`` tags. Without the ``--match v*`` filter in
+``[tool.hatch] version.raw-options.git_describe_command``, ``git describe``
+walks back to those subpackage tags and reports a version like ``0.2.0`` for
+a from-source build of zarr-python itself — see
+https://github.com/zarr-developers/zarr-python/pull/3994.
+
+This test catches that class of regression: anything that makes zarr-python
+report a version lower than the v3 release line. When 4.0 is released,
+bump the floor; that's a deliberate, one-line edit at a planned boundary.
+"""
+
+from __future__ import annotations
+
+from packaging.version import Version
+
+import zarr
+
+
+def test_version_is_v3_or_newer() -> None:
+    # Use packaging.Version so we transparently handle hatch-vcs dev suffixes
+    # like "3.2.2.dev30+gdc5e1825" that appear on any source build past the
+    # latest v* tag — Version.major returns 3 for that string.
+    parsed = Version(zarr.__version__)
+    assert parsed.major >= 3, (
+        f"zarr.__version__={zarr.__version__!r} is not on the v3 (or newer) "
+        f"release line. If this fires on a from-source build, check that "
+        f"[tool.hatch] version.raw-options.git_describe_command in "
+        f"pyproject.toml still includes ``--match v*`` so the "
+        f"``zarr_metadata-v*`` subpackage tags are excluded. See PR #3994."
+    )