uses python-finder during env activate

pyproject.toml

@@ -68,6 +68,7 @@ virtualenv = "(>=20.4.3,<20.4.5 || >=20.4.7)"
 xattr = { version = "^0.9.7", markers = "sys_platform == 'darwin'" }
 urllib3 = "^1.26.0"
 dulwich = "^0.20.44"
+pythonfinder = "^1.2.10"
 
 [tool.poetry.dev-dependencies]
 tox = "^3.18"
@@ -155,6 +156,7 @@ module = [
   'crashtest.*',
   'pexpect.*',
   'pkginfo.*',
+  'pythonfinder',
   'requests_toolbelt.*',
   'shellingham.*',
   'virtualenv.*',

src/poetry/config/config.py

@@ -124,7 +124,11 @@ class Config:
             "prefer-active-python": False,
             "prompt": "{project_name}-py{python_version}",
         },
-        "experimental": {"new-installer": True, "system-git-client": False},
+        "experimental": {
+            "new-installer": True,
+            "system-git-client": False,
+            "python-finder": True,
+        },
         "installer": {"parallel": True, "max-workers": None, "no-binary": None},
     }
 
@@ -266,6 +270,7 @@ def _get_normalizer(name: str) -> Callable[[str], Any]:
             "virtualenvs.options.system-site-packages",
             "virtualenvs.options.prefer-active-python",
             "experimental.new-installer",
+            "experimental.python-finder",
             "experimental.system-git-client",
             "installer.parallel",
         }:

src/poetry/utils/env.py

@@ -34,6 +34,7 @@
 from poetry.core.semver.version import Version
 from poetry.core.toml.file import TOMLFile
 from poetry.core.utils.helpers import temporary_directory
+from pythonfinder import Finder
 from virtualenv.seed.wheels.embed import get_embed_wheel
 
 from poetry.utils._compat import WINDOWS
@@ -505,6 +506,13 @@ def __init__(self, expected: str, given: str) -> None:
         super().__init__(message)
 
 
+class InterpreterNotFound(EnvError):
+    def __init__(self, python: str) -> None:
+        message = f"Python interpreter not found for input ({python})"
+
+        super().__init__(message)
+
+
 class EnvManager:
     """
     Environments manager
@@ -551,23 +559,7 @@ def _detect_active_python(self, io: IO) -> str | None:
             )
         return executable
 
-    def activate(self, python: str, io: IO) -> Env:
-        venv_path = self._poetry.config.virtualenvs_path
-        cwd = self._poetry.file.parent
-
-        envs_file = TOMLFile(venv_path / self.ENVS_FILE)
-
-        try:
-            python_version = Version.parse(python)
-            python = f"python{python_version.major}"
-            if python_version.precision > 1:
-                python += f".{python_version.minor}"
-        except ValueError:
-            # Executable in PATH or full executable path
-            pass
-
-        python = self._full_python_path(python)
-
+    def _get_python_versions(self, python: str) -> tuple[str, str]:
         try:
             python_version_string = decode(
                 subprocess.check_output(
@@ -581,6 +573,52 @@ def activate(self, python: str, io: IO) -> Env:
         python_version = Version.parse(python_version_string.strip())
         minor = f"{python_version.major}.{python_version.minor}"
         patch = python_version.text
+        return minor, patch
+
+    def _find_python(self, python: str) -> tuple[str, str, str]:
+        # Handle full path
+        path = Path(python)
+        if path.is_absolute():
+            if path.exists():
+                minor, patch = self._get_python_versions(python)
+                return python, minor, patch
+            else:
+                raise InterpreterNotFound(python)
+
+        # python is either <major>[.<minor>] or python[<major>[.<minor>]]
+        # both are supported as first parameter to Finder.find_python_version
+        finder = Finder(sort_by_path=True)
+        try:
+            result = finder.find_python_version(python)
+            if result:
+                minor = f"{result.py_version.major}.{result.py_version.minor}"
+                patch = f"{minor}.{result.py_version.patch}"
+                return str(result.path), minor, patch
+        except ValueError:
+            pass
+
+        raise InterpreterNotFound(python)
+
+    def activate(self, python: str, io: IO) -> Env:
+        venv_path = self._poetry.config.virtualenvs_path
+        cwd = self._poetry.file.parent
+
+        envs_file = TOMLFile(venv_path / self.ENVS_FILE)
+
+        experimental_finder = self._poetry.config.get("experimental.python-finder")
+        if experimental_finder:
+            python, minor, patch = self._find_python(python)
+        else:
+            try:
+                python_version = Version.parse(python)
+                python = f"python{python_version.major}"
+                if python_version.precision > 1:
+                    python += f".{python_version.minor}"
+            except ValueError:
+                # Executable in PATH or full executable path
+                pass
+            python = self._full_python_path(python)
+            minor, patch = self._get_python_versions(python)
 
         create = False
         is_root_venv = self._poetry.config.get("virtualenvs.in-project")

tests/conftest.py

@@ -43,6 +43,7 @@
 
     from _pytest.config import Config as PyTestConfig
     from _pytest.config.argparsing import Parser
+    from _pytest.fixtures import FixtureRequest
     from pytest_mock import MockerFixture
 
     from poetry.poetry import Poetry
@@ -486,3 +487,16 @@ def load_required_fixtures(
 ) -> None:
     for fixture in required_fixtures:
         fixture_copier(fixture)
+
+
+@pytest.fixture(params=[True, False])
+def find_python_mode(config: Config, request: FixtureRequest) -> None:
+    config.merge(
+        {
+            "experimental": {
+                # param is an optional attribute present
+                # when fixtures are parameterized
+                "python-finder": request.param  # type: ignore
+            }
+        }
+    )

tests/console/commands/env/helpers.py

@@ -33,3 +33,13 @@ def check_output(cmd: str, *_: Any, **__: Any) -> str:
             return str(Path("/prefix"))
 
     return check_output
+
+
+def find_python_wrapper(
+    version: PEP440Version = VERSION_3_7_1,
+) -> Callable[[str], tuple[str, str, str]]:
+    def find_python_output(python: str) -> tuple[str, str, str]:
+        path = f"/usr/bin/python{version.major}.{version.minor}"
+        return path, f"{version.major}.{version.minor}", version.text
+
+    return find_python_output

tests/console/commands/env/test_use.py

@@ -14,6 +14,7 @@
 from poetry.utils.env import MockEnv
 from tests.console.commands.env.helpers import build_venv
 from tests.console.commands.env.helpers import check_output_wrapper
+from tests.console.commands.env.helpers import find_python_wrapper
 
 
 if TYPE_CHECKING:
@@ -34,18 +35,25 @@ def setup(mocker: MockerFixture) -> None:
 def mock_subprocess_calls(
     setup: None, current_python: tuple[int, int, int], mocker: MockerFixture
 ) -> None:
+    version = Version.from_parts(*current_python)
     mocker.patch(
         "subprocess.check_output",
-        side_effect=check_output_wrapper(Version.from_parts(*current_python)),
+        side_effect=check_output_wrapper(version),
     )
     mocker.patch(
         "subprocess.Popen.communicate",
         side_effect=[("/prefix", None), ("/prefix", None), ("/prefix", None)],
     )
+    mocker.patch(
+        "poetry.utils.env.EnvManager._find_python",
+        side_effect=find_python_wrapper(version),
+    )
 
 
 @pytest.fixture
-def tester(command_tester_factory: CommandTesterFactory) -> CommandTester:
+def tester(
+    command_tester_factory: CommandTesterFactory, find_python_mode: None
+) -> CommandTester:
     return command_tester_factory("env use")
 
 
@@ -60,6 +68,9 @@ def test_activate_activates_non_existing_virtualenv_no_envs_file(
         "subprocess.check_output",
         side_effect=check_output_wrapper(),
     )
+    mocker.patch(
+        "poetry.utils.env.EnvManager._find_python", side_effect=find_python_wrapper()
+    )
 
     mock_build_env = mocker.patch(
         "poetry.utils.env.EnvManager.build_venv", side_effect=build_venv

tests/console/commands/test_config.py

@@ -52,6 +52,7 @@ def test_list_displays_default_value_if_not_set(
     venv_path = json.dumps(os.path.join("{cache-dir}", "virtualenvs"))
     expected = f"""cache-dir = {cache_dir}
 experimental.new-installer = true
+experimental.python-finder = true
 experimental.system-git-client = false
 installer.max-workers = null
 installer.no-binary = null
@@ -81,6 +82,7 @@ def test_list_displays_set_get_setting(
     venv_path = json.dumps(os.path.join("{cache-dir}", "virtualenvs"))
     expected = f"""cache-dir = {cache_dir}
 experimental.new-installer = true
+experimental.python-finder = true
 experimental.system-git-client = false
 installer.max-workers = null
 installer.no-binary = null
@@ -134,6 +136,7 @@ def test_list_displays_set_get_local_setting(
     venv_path = json.dumps(os.path.join("{cache-dir}", "virtualenvs"))
     expected = f"""cache-dir = {cache_dir}
 experimental.new-installer = true
+experimental.python-finder = true
 experimental.system-git-client = false
 installer.max-workers = null
 installer.no-binary = null