Repository: pypa/build
Pull request #736 (2024-02-19 22:26:50)

feat: use external pip if available
Trying #733 out. Pip is used if it is in the same environment as build and new enough. Saves a bit of time setting up the venvs. Haven't worked on tests yet.

From quick testing building both an sdist and wheel for itself with virtualenv installed this goes from about 4.7 seconds to 3.2 seconds. With `venv` only, it goes from 10.5 seconds to 4.4 seconds.

FYI, with `uv` (hacked in) it took 2.36 secs.

(This is a very simple build, of course, with only a small handful of deps)

uv's experimental native build support took 571ms, but that's only building the wheel (above is SDist and wheel).


Patch:
diff --git a/src/build/env.py b/src/build/env.py
index 3dc909f..95ba9d1 100644
--- a/src/build/env.py
+++ b/src/build/env.py
@@ -70,26 +70,42 @@ def _minimum_pip_version() -> str:
     return '19.1.0'
 
 
-def _has_valid_pip(purelib: str) -> bool:
+def _has_valid_pip(**distargs: object) -> bool:
     """
     Given a path, see if Pip is present and return True if the version is
-    sufficient for build, False if it is not.
+    sufficient for build, False if it is not. ModuleNotFoundError is thrown if
+    pip is not present.
     """
 
     import packaging.version
 
-    if sys.version_info < (3, 8):
-        import importlib_metadata as metadata
-    else:
-        from importlib import metadata
+    from ._importlib import metadata
+
+    name = 'pip'
 
-    pip_distribution = next(iter(metadata.distributions(name='pip', path=[purelib])))
+    try:
+        pip_distribution = next(iter(metadata.distributions(name=name, **distargs)))
+    except StopIteration:
+        raise ModuleNotFoundError(name) from None
 
     current_pip_version = packaging.version.Version(pip_distribution.version)
 
     return current_pip_version >= packaging.version.Version(_minimum_pip_version())
 
 
+@functools.lru_cache(maxsize=None)
+def _valid_global_pip() -> bool | None:
+    """
+    This checks for a valid global pip. Returns None if pip is missing, False
+    if Pip is too old, and True if it can be used.
+    """
+
+    try:
+        return _has_valid_pip()
+    except ModuleNotFoundError:
+        return None
+
+
 def _subprocess(cmd: list[str]) -> None:
     """Invoke subprocess and output stdout and stderr if it fails."""
     try:
@@ -139,6 +155,12 @@ class DefaultIsolatedEnv(IsolatedEnv):
         """The python executable of the isolated build environment."""
         return self._python_executable
 
+    def _pip_args(self) -> list[str]:
+        if _valid_global_pip():
+            return [sys.executable, '-Im', 'pip', '--python', self.python_executable]
+        else:
+            return [self.python_executable, '-Im', 'pip']
+
     def make_extra_environ(self) -> dict[str, str]:
         path = os.environ.get('PATH')
         return {'PATH': os.pathsep.join([self._scripts_dir, path]) if path is not None else self._scripts_dir}
@@ -163,9 +185,7 @@ class DefaultIsolatedEnv(IsolatedEnv):
             req_file.write(os.linesep.join(requirements))
         try:
             cmd = [
-                self.python_executable,
-                '-Im',
-                'pip',
+                *self._pip_args(),
                 'install',
                 '--use-pep517',
                 '--no-warn-script-location',
@@ -201,7 +221,11 @@ def _create_isolated_env_virtualenv(path: str) -> tuple[str, str]:
     """
     import virtualenv
 
-    cmd = [str(path), '--no-setuptools', '--no-wheel', '--activators', '']
+    if _valid_global_pip():
+        cmd = [path, '--no-seed', '--activators', '']
+    else:
+        cmd = [path, '--no-setuptools', '--no-wheel', '--activators', '']
+
     result = virtualenv.cli_run(cmd, setup_logging=False)
     executable = str(result.creator.exe)
     script_dir = str(result.creator.script_dir)
@@ -240,18 +264,20 @@ def _create_isolated_env_venv(path: str) -> tuple[str, str]:
         with warnings.catch_warnings():
             if sys.version_info[:3] == (3, 11, 0):
                 warnings.filterwarnings('ignore', 'check_home argument is deprecated and ignored.', DeprecationWarning)
-            venv.EnvBuilder(with_pip=True, symlinks=symlinks).create(path)
+            venv.EnvBuilder(with_pip=not _valid_global_pip(), symlinks=symlinks).create(path)
     except subprocess.CalledProcessError as exc:
         raise FailedProcessError(exc, 'Failed to create venv. Maybe try installing virtualenv.') from None
 
     executable, script_dir, purelib = _find_executable_and_scripts(path)
 
     # Get the version of pip in the environment
-    if not _has_valid_pip(purelib):
+    if not _valid_global_pip() and not _has_valid_pip(path=[purelib]):
         _subprocess([executable, '-m', 'pip', 'install', f'pip>={_minimum_pip_version()}'])
 
     # Avoid the setuptools from ensurepip to break the isolation
-    _subprocess([executable, '-m', 'pip', 'uninstall', 'setuptools', '-y'])
+    if not _valid_global_pip():
+        _subprocess([executable, '-m', 'pip', 'uninstall', 'setuptools', '-y'])
+
     return executable, script_dir
 
 


Test patch:
diff --git a/tests/conftest.py b/tests/conftest.py
index ecc2538..8f989d6 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -65,6 +65,11 @@ def is_integration(item):
     return os.path.basename(item.location[0]) == 'test_integration.py'
 
 
+@pytest.fixture()
+def local_pip(monkeypatch):
+    monkeypatch.setattr(build.env, '_valid_global_pip', lambda: None)
+
+
 @pytest.fixture(scope='session', autouse=True)
 def ensure_syconfig_vars_created():
     # the config vars are globally cached and may use get_path, make sure they are created
diff --git a/tests/test_env.py b/tests/test_env.py
index 41d1f47..feaf042 100644
--- a/tests/test_env.py
+++ b/tests/test_env.py
@@ -26,6 +26,7 @@ def test_isolation():
 
 
 @pytest.mark.isolated
+@pytest.mark.usefixtures('local_pip')
 def test_isolated_environment_install(mocker):
     with build.env.DefaultIsolatedEnv() as env:
         mocker.patch('build.env._subprocess')
@@ -117,6 +118,7 @@ def test_isolated_env_log(mocker, caplog, package_test_flit):
 
 
 @pytest.mark.isolated
+@pytest.mark.usefixtures('local_pip')
 def test_default_pip_is_never_too_old():
     with build.env.DefaultIsolatedEnv() as env:
         version = subprocess.check_output(
@@ -130,6 +132,7 @@ def test_default_pip_is_never_too_old():
 @pytest.mark.isolated
 @pytest.mark.parametrize('pip_version', ['20.2.0', '20.3.0', '21.0.0', '21.0.1'])
 @pytest.mark.parametrize('arch', ['x86_64', 'arm64'])
+@pytest.mark.usefixtures('local_pip')
 def test_pip_needs_upgrade_mac_os_11(mocker, pip_version, arch):
     SimpleNamespace = collections.namedtuple('SimpleNamespace', 'version')
 
@@ -137,8 +140,7 @@ def test_pip_needs_upgrade_mac_os_11(mocker, pip_version, arch):
     mocker.patch('platform.system', return_value='Darwin')
     mocker.patch('platform.machine', return_value=arch)
     mocker.patch('platform.mac_ver', return_value=('11.0', ('', '', ''), ''))
-    metadata_name = 'importlib_metadata' if sys.version_info < (3, 8) else 'importlib.metadata'
-    mocker.patch(metadata_name + '.distributions', return_value=(SimpleNamespace(version=pip_version),))
+    mocker.patch('build._importlib.metadata.distributions', return_value=(SimpleNamespace(version=pip_version),))
 
     min_version = Version('20.3' if arch == 'x86_64' else '21.0.1')
     with build.env.DefaultIsolatedEnv():
diff --git a/tests/test_main.py b/tests/test_main.py
index 8edc309..2ca18e4 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -342,6 +342,7 @@ def main_reload_styles():
     ],
     ids=['no-color', 'color'],
 )
+@pytest.mark.usefixtures('local_pip')
 def test_output_env_subprocess_error(
     mocker,
     monkeypatch,