packages: unify python project check

src/poetry/core/packages/dependency.py

@@ -490,7 +490,7 @@ def create_from_pep_508(
         from poetry.core.packages.url_dependency import URLDependency
         from poetry.core.packages.utils.link import Link
         from poetry.core.packages.utils.utils import is_archive_file
-        from poetry.core.packages.utils.utils import is_installable_dir
+        from poetry.core.packages.utils.utils import is_python_project
         from poetry.core.packages.utils.utils import is_url
         from poetry.core.packages.utils.utils import path_to_url
         from poetry.core.packages.utils.utils import strip_extras
@@ -521,10 +521,9 @@ def create_from_pep_508(
             path_str = os.path.normpath(os.path.abspath(name))
             p, extras = strip_extras(path_str)
             if os.path.isdir(p) and (os.path.sep in name or name.startswith(".")):
-
-                if not is_installable_dir(p):
+                if not is_python_project(Path(name)):
                     raise ValueError(
-                        f"Directory {name!r} is not installable. File 'setup.py' "
+                        f"Directory {name!r} is not installable. File 'setup.[py|cfg]' "
                         "not found."
                     )
                 link = Link(path_to_url(p))

src/poetry/core/packages/directory_dependency.py

@@ -1,14 +1,19 @@
 from __future__ import annotations
 
+import functools
+
 from pathlib import Path
 from typing import TYPE_CHECKING
 from typing import Iterable
 
+from poetry.core.pyproject.toml import PyProjectTOML
+
 
 if TYPE_CHECKING:
     from poetry.core.semver.version_constraint import VersionConstraint
 
 from poetry.core.packages.dependency import Dependency
+from poetry.core.packages.utils.utils import is_python_project
 from poetry.core.packages.utils.utils import path_to_url
 
 
@@ -23,7 +28,6 @@ def __init__(
         develop: bool = False,
         extras: Iterable[str] | None = None,
     ) -> None:
-        from poetry.core.pyproject.toml import PyProjectTOML
 
         self._path = path
         self._base = base or Path.cwd()
@@ -43,18 +47,7 @@ def __init__(
         if self._full_path.is_file():
             raise ValueError(f"{self._path} is a file, expected a directory")
 
-        # Checking content to determine actions
-        setup_py = self._full_path / "setup.py"
-        setup_cfg = self._full_path / "setup.cfg"
-        setuptools_project = setup_py.exists() or setup_cfg.exists()
-        pyproject = PyProjectTOML(self._full_path / "pyproject.toml")
-
-        self._supports_pep517 = (
-            setuptools_project or pyproject.is_build_system_defined()
-        )
-        self._supports_poetry = pyproject.is_poetry_project()
-
-        if not (self._supports_pep517 or self._supports_poetry):
+        if not is_python_project(self._full_path):
             raise ValueError(
                 f"Directory {self._full_path} does not seem to be a Python package"
             )
@@ -70,6 +63,9 @@ def __init__(
             extras=extras,
         )
 
+        # cache this function to avoid multiple IO reads and parsing
+        self.supports_poetry = functools.lru_cache(maxsize=1)(self._supports_poetry)
+
     @property
     def path(self) -> Path:
         return self._path
@@ -86,8 +82,8 @@ def base(self) -> Path:
     def develop(self) -> bool:
         return self._develop
 
-    def supports_poetry(self) -> bool:
-        return self._supports_poetry
+    def _supports_poetry(self) -> bool:
+        return PyProjectTOML(self._full_path / "pyproject.toml").is_poetry_project()
 
     def is_directory(self) -> bool:
         return True

src/poetry/core/packages/utils/utils.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-import os
+import functools
 import posixpath
 import re
 import sys
@@ -14,6 +14,7 @@
 from urllib.parse import urlsplit
 from urllib.request import url2pathname
 
+from poetry.core.pyproject.toml import PyProjectTOML
 from poetry.core.semver.version_range import VersionRange
 from poetry.core.version.markers import dnf
 
@@ -119,14 +120,22 @@ def strip_extras(path: str) -> tuple[str, str | None]:
     return path_no_extras, extras
 
 
-def is_installable_dir(path: str) -> bool:
-    """Return True if `path` is a directory containing a setup.py file."""
-    if not os.path.isdir(path):
+@functools.lru_cache(maxsize=None)
+def is_python_project(path: Path) -> bool:
+    """Return true if the directory is a Python project"""
+    if not path.is_dir():
         return False
-    setup_py = os.path.join(path, "setup.py")
-    if os.path.isfile(setup_py):
-        return True
-    return False
+
+    setup_py = path / "setup.py"
+    setup_cfg = path / "setup.cfg"
+    setuptools_project = setup_py.exists() or setup_cfg.exists()
+
+    pyproject = PyProjectTOML(path / "pyproject.toml")
+
+    supports_pep517 = setuptools_project or pyproject.is_build_system_defined()
+    supports_poetry = pyproject.is_poetry_project()
+
+    return supports_pep517 or supports_poetry
 
 
 def is_archive_file(name: str) -> bool:

tests/packages/utils/test_utils.py

@@ -1,9 +1,12 @@
 from __future__ import annotations
 
+from pathlib import Path
+
 import pytest
 
 from poetry.core.packages.utils.utils import convert_markers
 from poetry.core.packages.utils.utils import get_python_constraint_from_marker
+from poetry.core.packages.utils.utils import is_python_project
 from poetry.core.semver.helpers import parse_constraint
 from poetry.core.version.markers import parse_marker
 
@@ -132,3 +135,19 @@ def test_get_python_constraint_from_marker(marker: str, constraint: str) -> None
     marker_parsed = parse_marker(marker)
     constraint_parsed = parse_constraint(constraint)
     assert get_python_constraint_from_marker(marker_parsed) == constraint_parsed
+
+
+@pytest.mark.parametrize(
+    ("fixture", "result"),
+    [
+        ("simple_project", True),
+        ("project_with_setup_cfg_only", True),
+        ("project_with_setup", True),
+        ("project_with_pep517_non_poetry", True),
+        ("project_without_pep517", False),
+        ("does_not_exist", False),
+    ],
+)
+def test_package_utils_is_python_project(fixture: str, result: bool) -> None:
+    path = Path(__file__).parent.parent.parent / "fixtures" / fixture
+    assert is_python_project(path) == result