ENH: do not use the 'meson compile' indirection to build the project

meson-python already assumes that the meson build backed is ninja,
thus there is no advantage in going through the backend agnostic meson
compile command. Invoking ninja directly saves about 200 ms on an
average system. This is relevant for editable wheel installations,
where the project rebuild is triggered on import.

Fixes #324.

Author: dnicolodi

mesonpy/__init__.py

@@ -681,9 +681,10 @@ def __init__(  # noqa: C901
         self._env = os.environ.copy()
 
         # prepare environment
-        ninja_path = _env_ninja_command()
-        if ninja_path is not None:
-            self._env.setdefault('NINJA', str(ninja_path))
+        self._ninja = _env_ninja_command()
+        if self._ninja is None:
+            raise ConfigError(f'Could not find ninja version {_NINJA_REQUIRED_VERSION} or newer.')
+        self._env.setdefault('NINJA', self._ninja)
 
         # setuptools-like ARCHFLAGS environment variable support
         if sysconfig.get_platform().startswith('macosx-'):
@@ -857,8 +858,9 @@ def _wheel_builder(self) -> _WheelBuilder:
         )
 
     def build_commands(self, install_dir: Optional[pathlib.Path] = None) -> Sequence[Sequence[str]]:
+        assert self._ninja is not None  # help mypy out
         return (
-            ('meson', 'compile', *self._meson_args['compile'],),
+            (self._ninja, *self._meson_args['compile'],),
             (
                 'meson',
                 'install',

tests/test_project.py

@@ -2,10 +2,7 @@
 #
 # SPDX-License-Identifier: MIT
 
-import contextlib
 import platform
-import subprocess
-import sys
 
 import pytest
 
@@ -52,35 +49,29 @@ def test_unsupported_python_version(package_unsupported_python_version):
             pass
 
 
-@pytest.mark.skipif(
-    sys.version_info < (3, 8),
-    reason="unittest.mock doesn't support the required APIs for this test",
-)
-def test_user_args(package_user_args, mocker, tmp_path_session):
-    mocker.patch('mesonpy.Project._meson')
+def test_user_args(package_user_args, tmp_path, monkeypatch):
+    project_run = mesonpy.Project._run
+    call_args_list = []
 
-    def last_two_meson_args():
-        return [call.args[-2:] for call in mesonpy.Project._meson.call_args_list]
+    def wrapper(self, cmd):
+        # intercept and filter out test arguments and forward the call
+        call_args_list.append(tuple(cmd))
+        return project_run(self, [x for x in cmd if not x.startswith(('config-', 'cli-'))])
+
+    monkeypatch.setattr(mesonpy.Project, '_run', wrapper)
 
-    # create the build directory ourselves because Project._meson is mocked
-    builddir = str(tmp_path_session / 'build')
+    def last_two_meson_args():
+        return [args[-2:] for args in call_args_list]
 
     config_settings = {
-        'builddir': builddir,  # use the build directory we created
         'dist-args': ('cli-dist',),
         'setup-args': ('cli-setup',),
         'compile-args': ('cli-compile',),
         'install-args': ('cli-install',),
     }
 
-    with contextlib.suppress(FileNotFoundError):
-        mesonpy.build_sdist(tmp_path_session / 'dist', config_settings)
-
-    # run setup ourselves because Project._meson is mocked
-    subprocess.run(['meson', 'setup', '.', builddir], check=True)
-
-    with contextlib.suppress(FileNotFoundError):
-        mesonpy.build_wheel(tmp_path_session / 'dist', config_settings)
+    mesonpy.build_sdist(tmp_path, config_settings)
+    mesonpy.build_wheel(tmp_path, config_settings)
 
     assert last_two_meson_args() == [
         # sdist: calls to 'meson setup' and 'meson dist'