setup.cfg: require minimum versions of dependencies

This fixes issues where an old version of requirements are cached on a users system, causing build to break on install. Testing by manually loading old versions of packages in tox.

.github/workflows/check.yml

@@ -86,6 +86,9 @@ jobs:
       - name: Run test suite via wheel
         run: tox -e ${{env.BASE}}-wheel --skip-pkg-install
 
+      - name: Run minimum version test
+        run: tox -e ${{env.BASE}}-minversion
+
       - name: Rename coverage report file
         run: |
           import os; os.rename('.tox/coverage.{}.xml'.format(os.environ['BASE']), '.tox/coverage.xml')

setup.cfg

@@ -27,11 +27,11 @@ project_urls =
 [options]
 packages = find:
 install_requires =
-    packaging
-    pep517>=0.9
-    toml
-    importlib-metadata;python_version < "3.8"
-    typing;python_version<"3"
+    packaging>=19.0
+    pep517>=0.9.1
+    toml>=0.10.0
+    importlib-metadata>=0.22;python_version < "3.8"
+    typing>=3.5.2;python_version < "3"
     virtualenv>=20.0.35;python_version < "3"
 python_requires = >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*
 package_dir =
@@ -49,6 +49,13 @@ docs =
     sphinx~=3.0
     sphinx-argparse-cli>=1.5
     sphinx-autodoc-typehints>=1.10
+lockminversions =
+    packaging==19.0
+    pep517==0.9.1
+    toml==0.10.0
+    importlib-metadata==0.22;python_version < "3.8"
+    typing==3.5.2.2;python_version < "3"
+    virtualenv==20.0.35;python_version < "3"
 test =
     filelock>=3
     pytest>=4

tox.ini

@@ -4,6 +4,7 @@ envlist =
     type
     docs
     {py39, py38, py37, py36, py35, py27, pypy3, pypy2}{, -path, -sdist, -wheel}
+    {py27, py35, py39}-minversion
 isolated_build = true
 skip_missing_interpreters = true
 minversion = 3.14
@@ -55,6 +56,14 @@ commands =
     mypy --python-version 3.5 src/build
     mypy --python-version 2.7 src/build
 
+[testenv:minversion]
+description = check minimum versions required of all dependencies
+extras =
+    test
+    lockminversions
+commands =
+    pytest -rsx tests {posargs:-n auto}
+
 [testenv:docs]
 description = build documentations
 basepython = python3.8