feat: upper cap check (#501)

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

.pre-commit-config.yaml

@@ -54,7 +54,7 @@ repos:
           - pytest
           - repo-review>=0.10.6
           - rich
-          - tomli
+          - tomli>=2.0.2
           - types-PyYAML
 
   - repo: https://github.com/rbubley/mirrors-prettier

README.md

@@ -323,6 +323,7 @@ for family, grp in itertools.groupby(collected.checks.items(), key=lambda x: x[1
 ### PyProject
 - [`PP002`](https://learn.scientific-python.org/development/guides/packaging-simple#PP002): Has a proper build-system table
 - [`PP003`](https://learn.scientific-python.org/development/guides/packaging-classic#PP003): Does not list wheel as a build-dep
+- [`PP004`](https://learn.scientific-python.org/development/guides/packaging-simple#PP004): Does not upper cap Python requires
 - [`PP301`](https://learn.scientific-python.org/development/guides/pytest#PP301): Has pytest in pyproject
 - [`PP302`](https://learn.scientific-python.org/development/guides/pytest#PP302): Sets a minimum pytest to at least 6
 - [`PP303`](https://learn.scientific-python.org/development/guides/pytest#PP303): Sets the test paths

docs/pages/guides/packaging_simple.md

@@ -79,6 +79,11 @@ build-backend = "setuptools.build_meta"
 
 {% include pyproject.md %}
 
+For `requires-python`, you should specify the minimum you require, and you
+should not put an upper cap on it {% rr PY004 %}, as this field is used to
+back-solve for old package versions that pass this check, allowing you to safely
+drop Python versions.
+
 ## Package structure
 
 All packages _should_ have a `src` folder, with the package code residing inside

src/sp_repo_review/checks/pyproject.py

@@ -2,6 +2,7 @@
 
 from typing import Any
 
+from .._compat.importlib.resources.abc import Traversable
 from . import mk_url
 
 
@@ -50,6 +51,48 @@ def check(pyproject: dict[str, Any]) -> bool:
                 return False
 
 
+class PP004(PyProject):
+    "Does not upper cap Python requires"
+
+    url = mk_url("packaging-simple")
+
+    @staticmethod
+    def check(pyproject: dict[str, Any], package: Traversable) -> bool | None:
+        """
+        You should never upper cap your Python requirement. This is rarely correct, and
+        tools like pip do not handle this properly even if it is correct. This field is used
+        to back-solve. If you want to specify versions you've tested on, use classifiers. If
+        you want to add a custom error message, add a build-type and/or runtime assert.
+        """
+
+        match pyproject:
+            case {"project": {"requires-python": requires}}:
+                return "~=" not in requires and "<" not in requires
+            case {
+                "tool": {
+                    "poetry": {
+                        "dependencies": {
+                            "python": str(requires) | {"version": str(requires)}
+                        }
+                    }
+                }
+            }:
+                return (
+                    "^" not in requires and "~=" not in requires and "<" not in requires
+                )
+
+        setup_cfg = package / "setup.cfg"
+        if setup_cfg.is_file():
+            import configparser
+
+            config = configparser.ConfigParser()
+            config.read_string(setup_cfg.read_text(encoding="utf-8"))
+            if requires := config.get("options", "python_requires"):
+                return "~=" not in requires and "<" not in requires
+
+        return None
+
+
 class PP301(PyProject):
     "Has pytest in pyproject"
 

src/sp_repo_review/checks/ruff.py

@@ -31,8 +31,7 @@ def ruff(pyproject: dict[str, Any], root: Traversable) -> dict[str, Any] | None:
     for path in paths:
         if path.is_file():
             with path.open("rb") as f:
-                # Type ignore fixed in https://github.com/hukkin/tomli/pull/215
-                contents = tomllib.load(f)  # type: ignore[arg-type]
+                contents = tomllib.load(f)
             if contents.get("extend", "") == "pyproject.toml":
                 extend = pyproject.get("tool", {}).get("ruff", {})
                 return merge(extend, contents)

tests/test_pyproject.py

@@ -1,3 +1,6 @@
+import inspect
+from pathlib import Path
+
 from repo_review.testing import compute_check, toml_loads
 
 
@@ -46,6 +49,70 @@ def test_PP003_has_wheel():
     assert not compute_check("PP003", pyproject=toml).result
 
 
+def test_PP004_no_cap_pyproject(tmp_path: Path):
+    toml = toml_loads("""
+       [project]
+       requires-python = ">=3.10"
+       """)
+
+    assert compute_check("PP004", pyproject=toml, package=tmp_path).result
+
+
+def test_PP004_cap_pyproject(tmp_path: Path):
+    toml = toml_loads("""
+        [project]
+        requires-python = ">=3.10, <4"
+        """)
+
+    assert compute_check("PP004", pyproject=toml, package=tmp_path).result is False
+
+
+def test_PP004_cap_tilde_pyproject(tmp_path: Path):
+    toml = toml_loads("""
+        [project]
+        requires-python = "~=3.10"
+        """)
+
+    assert compute_check("PP004", pyproject=toml, package=tmp_path).result is False
+
+
+def test_PP004_cap_caret_pyproject(tmp_path: Path):
+    toml = toml_loads("""
+        [tool.poetry.dependencies]
+        python = "^3.10"
+       """)
+
+    assert compute_check("PP004", pyproject=toml, package=tmp_path).result is False
+
+
+def test_PP004_setup_cfg_no_cap(tmp_path: Path):
+    (tmp_path / "setup.cfg").write_text(
+        inspect.cleandoc("""
+            [options]
+            python_requires = >=3.10
+            """),
+        encoding="utf-8",
+    )
+
+    assert compute_check("PP004", pyproject={}, package=tmp_path).result
+
+
+def test_PP004_setup_cfg_cap(tmp_path: Path):
+    (tmp_path / "setup.cfg").write_text(
+        inspect.cleandoc("""
+            [options]
+            python_requires = >=3.10,<4
+            """),
+        encoding="utf-8",
+    )
+
+    assert compute_check("PP004", pyproject={}, package=tmp_path).result is False
+
+
+def test_PP004_not_present(tmp_path: Path):
+    assert compute_check("PP004", pyproject={}, package=tmp_path).result is None
+
+
 def test_PP302_okay_intstr():
     toml = toml_loads("""
         [tool.pytest.ini_options]