ci: Run linters with Python 3.8

We've been trying to create a Python 3.10 environment, and then run mypy
in that environment and tell it to make sure that all of the code is
correctly typed Python 3.8 code (the minimum version we support).

This doesn't work: when we install pytest-memray's dependencies in that
Python 3.10 environment, we might install versions of those dependencies
that require Python 3.10 and so use Python 3.10 syntax, and if so mypy
will fail to parse those files as Python 3.8 code.

So, until we drop support for Python 3.8, our linting run needs to
install our dependencies in a Python 3.8 environment rather than 3.10,
and we need to pin to versions of our linters that are compatible with
Python 3.8.

Signed-off-by: Matt Wozniski <mwozniski@bloomberg.net>

Author: godlygeek

.github/workflows/build.yml

@@ -46,26 +46,37 @@ jobs:
       - name: run test suite ${{ matrix.tox_env }}
         run: tox --skip-pkg-install -e ${{ matrix.tox_env }}
 
-  check:
-    name: check ${{ matrix.tox_env }}
+  docs:
+    name: check docs
     runs-on: ubuntu-22.04
-    strategy:
-      fail-fast: false
-      matrix:
-        tox_env:
-          - lint
-          - docs
     steps:
       - uses: actions/checkout@v5
       - name: setup Python 3.11
         uses: actions/setup-python@v6
         with:
           python-version: "3.11"
+      - name: install tox
+        run: python -m pip install tox
+      - name: install docs dependencies
+        run: tox -vv --notest -e docs
+      - name: check docs
+        run: tox --skip-pkg-install -e docs
+
+  lint:
+    name: lint
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v5
+      # mypy needs to be run with the oldest Python version we support.
+      - name: setup Python 3.8
+        uses: actions/setup-python@v6
+        with:
+          python-version: "3.8"
       - name: Install prettier
         run: npm install -g prettier
       - name: install tox
         run: python -m pip install tox
-      - name: setup test suite for ${{ matrix.tox_env }}
-        run: tox -vv --notest -e ${{ matrix.tox_env }}
-      - name: run test suite ${{ matrix.tox_env }}
-        run: tox --skip-pkg-install -e ${{ matrix.tox_env }}
+      - name: install lint dependencies
+        run: tox -vv --notest -e lint
+      - name: lint
+        run: tox --skip-pkg-install -e lint

pyproject.toml

@@ -31,10 +31,10 @@ optional-dependencies.docs = [
   "towncrier>=22.12",
 ]
 optional-dependencies.lint = [
-  "black==25.1.0",
+  "black==24.8.0",
   "ruff==0.12.7",
-  "isort==6.0.1",
-  "mypy==1.17.1",
+  "isort==5.13.2",
+  "mypy==1.14.1",
 ]
 optional-dependencies.test = [
   "anyio>=4.4.0",

tox.ini

@@ -48,7 +48,7 @@ commands =
 
 [testenv:lint]
 description = lint code in {basepython}
-basepython = python3.10
+basepython = python3.8
 extras =
     lint
 commands =