Add ability to identify min_python version

Author: ssbarnea

.flake8

@@ -5,3 +5,4 @@ extend-ignore =
   F401,  # duplicate of pylint W0611 (unused-import)
   F821,  # duplicate of pylint E0602 (undefined-variable)
   F841,  # duplicate of pylint W0612 (unused-variable)
+  DAR  # we don't use darling

.github/workflows/tox.yml

@@ -21,17 +21,15 @@ on:
 jobs:
   tox:
     name: ${{ matrix.name }}
-    runs-on: ${{ matrix.os }}
+    runs-on: ${{ matrix.os || 'ubuntu-latest' }}
     strategy:
       fail-fast: false
       matrix:
-        python-version:
-          - 3.9
-        os:
-          - ubuntu-20.04
         include:
           - name: lint
+            python-version: "3.9"
           - name: packaging
+            python-version: "3.9"
           - name: py37
             python-version: "3.7"
           - name: py38

.pre-commit-config.yaml

@@ -78,10 +78,14 @@ repos:
       - id: mypy
         # empty args needed in order to match mypy cli behavior
         args: ["--strict"]
+        additional_dependencies:
+          - pytest
   - repo: https://github.com/pycqa/pylint
     rev: v2.14.5
     hooks:
       - id: pylint
+        additional_dependencies:
+          - pytest
   # Keep last due to being considerably slower than the others:
   - repo: local
     hooks:
@@ -90,7 +94,7 @@ repos:
         name: Upgrade constraints files and requirements
         files: ^(setup\.py|setup\.cfg|requirements\.txt)$
         language: python
-        entry: python -m piptools compile --upgrade -q --extra docs --extra test --output-file=requirements.txt setup.cfg
+        entry: python -m piptools compile --upgrade -q --strip-extras --extra test --output-file=requirements.txt setup.cfg
         pass_filenames: false
         stages:
           - manual
@@ -100,7 +104,7 @@ repos:
         name: Check constraints files and requirements
         files: ^(setup\.py|setup\.cfg|requirements\.txt)$
         language: python
-        entry: python -m piptools compile -q --extra docs --extra test --output-file=requirements.txt setup.cfg
+        entry: python -m piptools compile -q --strip-extras --extra test --output-file=requirements.txt setup.cfg
         pass_filenames: false
         additional_dependencies:
           - pip-tools>=6.8.0

requirements.txt

@@ -2,11 +2,11 @@
 # This file is autogenerated by pip-compile with python 3.9
 # To update, run:
 #
-#    pip-compile --extra=docs --extra=test --output-file=requirements.txt setup.cfg
+#    pip-compile --extra=test --output-file=requirements.txt --strip-extras setup.cfg
 #
 attrs==22.1.0
     # via pytest
-coverage[toml]==6.4.2
+coverage==6.4.2
     # via pytest-cov
 iniconfig==1.1.1
     # via pytest
@@ -22,7 +22,7 @@ pytest==7.1.2
     # via
     #   ppinfo (setup.cfg)
     #   pytest-cov
-pytest-cov[all]==3.0.0
+pytest-cov==3.0.0
     # via ppinfo (setup.cfg)
 tomli==2.0.1
     # via

src/ppinfo/__init__.py

@@ -1 +1,29 @@
 """ppinfo package."""
+import configparser
+import os
+from pathlib import Path
+from typing import Union
+
+
+# pylint: disable=too-few-public-methods
+class Project:
+    """Class representing a python project."""
+
+    # 3.7 default value is used because at the time this library was
+    # written, this was the oldest still supported version of Python
+    min_python: str = "3.7"
+
+    def __init__(self, path: Union[Path, str] = Path(".")) -> None:
+        """Construct a python Project instance."""
+        if isinstance(path, str):
+            path = Path(path)
+        self.path = path
+
+        if (path / "setup.cfg").exists():
+            config = configparser.ConfigParser()
+            config.read(path / "setup.cfg")
+            if "options" in config:
+                value = config["options"].get("python_requires", None)
+                if not (value and value.startswith(">=")):
+                    raise NotImplementedError("Unable to parse python_requires")
+                self.min_python = value[2:]

test/fixtures/proj1/setup.cfg

@@ -0,0 +1 @@
+# empty setup.cfg file

test/fixtures/py310/setup.cfg

@@ -0,0 +1,2 @@
+[options]
+python_requires = >=3.10

test/test_ppinfo.py

@@ -1,7 +1,14 @@
 """Tests for ppinfo package."""
+import pytest
 
+from ppinfo import Project
 
-def test_import() -> None:
-    """Test that we can import ppinfo."""
-    # pylint: disable=unused-import,import-outside-toplevel
-    import ppinfo
+
+@pytest.mark.parametrize(
+    ("path", "expected_python"),
+    [("test/fixtures/proj1", "3.7"), ("test/fixtures/py310", "3.10")],
+)
+def test_min_version(path: str, expected_python: str) -> None:
+    """Test ability to find minimal version of python required."""
+    project = Project(path)
+    assert project.min_python == expected_python