fix "env use python" to use Python in PATH (#10187)

Author: radoering

src/poetry/utils/env/python/manager.py

@@ -229,13 +229,6 @@ def get_active_python(cls) -> Python | None:
 
         return None
 
-    @classmethod
-    def from_executable(cls, path: Path | str) -> Python:
-        try:
-            return cls(python=findpython.PythonVersion(executable=Path(path)))
-        except (FileNotFoundError, NotADirectoryError, ValueError):
-            raise ValueError(f"{path} is not a valid Python executable")
-
     @classmethod
     def get_system_python(cls) -> Python:
         """
@@ -252,10 +245,10 @@ def get_system_python(cls) -> Python:
 
     @classmethod
     def get_by_name(cls, python_name: str) -> Python | None:
-        if Path(python_name).exists():
-            with contextlib.suppress(ValueError):
-                # if it is a path try assuming it is an executable
-                return cls.from_executable(python_name)
+        # Ignore broken installations.
+        with contextlib.suppress(ValueError):
+            if python := ShutilWhichPythonProvider.find_python_by_name(python_name):
+                return cls(python=python)
 
         if python := findpython.find(python_name):
             return cls(python=python)

src/poetry/utils/env/python/providers.py

@@ -28,10 +28,16 @@ def create(cls) -> Self | None:
         return cls()
 
     def find_pythons(self) -> Iterable[findpython.PythonVersion]:
-        if path := shutil.which("python"):
-            return [findpython.PythonVersion(executable=Path(path))]
+        if python := self.find_python_by_name("python"):
+            return [python]
         return []
 
+    @classmethod
+    def find_python_by_name(cls, name: str) -> findpython.PythonVersion | None:
+        if path := shutil.which(name):
+            return findpython.PythonVersion(executable=Path(path))
+        return None
+
 
 @dataclasses.dataclass
 class PoetryPythonPathProvider(PathProvider):  # type: ignore[misc]

tests/utils/env/python/test_manager.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import platform
+import sys
 
 from typing import TYPE_CHECKING
 
@@ -95,3 +96,39 @@ def find_downloadable_versions_include_incompatible() -> None:
     assert len(
         list(Python.find_downloadable_versions(include_incompatible=True))
     ) > len(list(Python.find_downloadable_versions()))
+
+
+@pytest.mark.parametrize(
+    ("name", "expected_minor"),
+    [
+        ("3.9", 9),
+        ("3.10", 10),
+        ("3.11", None),
+    ],
+)
+def test_get_by_name_version(
+    mocked_python_register: MockedPythonRegister, name: str, expected_minor: int | None
+) -> None:
+    mocked_python_register("3.9.1", implementation="CPython", parent="a")
+    mocked_python_register("3.10.3", implementation="CPython", parent="b")
+
+    python = Python.get_by_name(name)
+    if expected_minor is None:
+        assert python is None
+    else:
+        assert python is not None
+        assert python.minor == expected_minor
+
+
+def test_get_by_name_python(without_mocked_findpython: None) -> None:
+    python = Python.get_by_name("python")
+    assert python is not None
+    assert python.version.major == 3
+    assert python.version.minor == sys.version_info.minor
+
+
+def test_get_by_name_path(without_mocked_findpython: None) -> None:
+    python = Python.get_by_name(sys.executable)
+    assert python is not None
+    assert python.version.major == 3
+    assert python.version.minor == sys.version_info.minor

tests/utils/env/python/test_python_providers.py

@@ -1,16 +1,27 @@
 from __future__ import annotations
 
+import sys
+
 from typing import TYPE_CHECKING
 
 from poetry.core.constraints.version import Version
 
 from poetry.utils.env.python.providers import PoetryPythonPathProvider
+from poetry.utils.env.python.providers import ShutilWhichPythonProvider
 
 
 if TYPE_CHECKING:
     from tests.types import MockedPoetryPythonRegister
 
 
+def test_shutil_which_python_provider() -> None:
+    provider = ShutilWhichPythonProvider.create()
+    assert provider
+    pythons = list(provider.find_pythons())
+    assert len(pythons) == 1
+    assert pythons[0].minor == sys.version_info.minor
+
+
 def test_poetry_python_path_provider_no_pythons() -> None:
     provider = PoetryPythonPathProvider.create()
     assert provider