Add a check which tests test-mindeps bounds

.github/workflows/test.yaml

@@ -62,6 +62,7 @@ jobs:
               - "mypy-maxpython"
               - "reference"
               - "check-min-python-is-tested"
+              - "check-mindeps-lower-bounds"
               - "twine-check"
               - "twine-check-minimum"
               - "check-sdist"

scripts/ensure_mindeps_match_lower_bounds.py

@@ -0,0 +1,49 @@
+# run via `tox r -e check-mindeps-lower-bounds`
+import pathlib
+import re
+import sys
+import tomllib
+
+import mddj.api
+from packaging.dependency_groups import DependencyGroupResolver
+from packaging.requirements import Requirement
+
+dj = mddj.api.DJ()
+REPO_ROOT = pathlib.Path(__file__).parent.parent
+
+# load 'test-mindeps', filtered only to the directly declared requirements, not the
+# includes
+with open(REPO_ROOT / "pyproject.toml", "rb") as f:
+    pyproject = tomllib.load(f)
+
+group_resolver = DependencyGroupResolver(pyproject["dependency-groups"])
+mindeps = [
+    r for r in group_resolver.lookup("test-mindeps") if isinstance(r, Requirement)
+]
+
+dependencies: tuple[str, ...] = dj.read.dependencies()
+dependency_lower_bounds = {}
+for dep in dependencies:
+    req = Requirement(dep)
+
+    # extract lower bounds via a regex
+    # this pattern is imperfect but is good enough for realistic versions
+    # it won't work on complex specifiers with multiple `>=` expressions, for example
+    match = re.search(r">=([0-9\.a-z]+)", str(req.specifier))
+    if match is None:
+        continue
+
+    dependency_lower_bounds[req.name] = match.group(1)
+
+for req in mindeps:
+    if req.name not in dependency_lower_bounds:
+        print(f"warning: {req} is in 'test-mindeps' but is not in dependencies")
+        continue
+
+    true_lower_bound = dependency_lower_bounds[req.name]
+    if not req.specifier.contains(true_lower_bound):
+        print(
+            f"ERROR: 'test-mindeps' lists {req}, which does not contain "
+            f"the true lower bound, {true_lower_bound!r}"
+        )
+        sys.exit(1)

tox.ini

@@ -2,6 +2,7 @@
 [tox]
 envlist =
     check-min-python-is-tested
+    check-mindeps-lower-bounds
     twine-check{,-minimum}
     check-sdist{,-minimum}
     reference
@@ -148,6 +149,13 @@ deps =
 description = Check the Requires-Python metadata against CI config
 commands = python scripts/ensure_min_python_is_tested.py
 
+[testenv:check-mindeps-lower-bounds]
+base = check_metadata_base
+# no need for a build backend for this
+deps =
+description = Check 'test-mindeps' against 'dependencies'
+commands = python scripts/ensure_mindeps_match_lower_bounds.py
+
 [testenv:twine-check{,-minimum}]
 base = check_metadata_base
 description =