MAINT: put back mesonpy.__version__

The module constant has been used to check meson-python version in
other projects, see discussion on #691.  Add a test to ensure that the
version recorded in pyproject.toml and mesonpy/__init__.py are kept in
sync.

RELEASE.rst

@@ -19,7 +19,7 @@ After that is done, you may release the project by following these steps:
 
    #. Create the release commit
 
-      #. Bump the versions in ``pyproject.toml``.
+      #. Bump the versions in ``pyproject.toml`` and in ``mesonpy/__init__.py``.
       #. Create ``CHANGELOG.rst`` section for the new release and fill it.
       #. The commit message should read: ``REL: set version to X.Y.Z``
 

mesonpy/__init__.py

@@ -79,6 +79,9 @@ class InvalidLicenseExpression(Exception):  # type: ignore[no-redef]
     MesonArgs = Mapping[MesonArgsKeys, List[str]]
 
 
+__version__ = '0.18.0.dev0'
+
+
 _PYPROJECT_METADATA_VERSION = tuple(map(int, pyproject_metadata.__version__.split('.')[:2]))
 _SUPPORTED_DYNAMIC_FIELDS = {'version', } if _PYPROJECT_METADATA_VERSION < (0, 9) else {'version', 'license', 'license-files'}
 

tests/test_consistency.py

@@ -11,6 +11,15 @@
 else:
     import tomli as tomllib
 
+import mesonpy
+
+
+def test_version():
+    pyproject = pathlib.Path(__file__).parent.parent.joinpath('pyproject.toml')
+    with open(pyproject, 'rb') as f:
+        project_version = tomllib.load(f)['project']['version']
+    assert mesonpy.__version__ == project_version
+
 
 def test_pyproject_dependencies():
     pyproject = pathlib.Path(__file__).parent.parent.joinpath('pyproject.toml')