mypy: a separate tox env for mypy

1 files changed, 25 insertions, 3 deletions

diff --git a/.github/workflows/quality.yml b/.github/workflows/quality.yml
index 5483f7b8..0901d5ca 100644
--- a/.github/workflows/quality.yml
+++ b/.github/workflows/quality.yml
@@ -46,15 +46,37 @@ jobs:
 
       - name: "Install dependencies"
         run: |
-          set -xe
-          python -VV
-          python -m site
           python -m pip install --require-hashes -r requirements/tox.pip
 
       - name: "Tox lint"
         run: |
           python -m tox -e lint
 
+  mypy:
+    name: "Check types"
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: "Check out the repo"
+        uses: "actions/checkout@v3"
+
+      - name: "Install Python"
+        uses: "actions/setup-python@v4"
+        with:
+          python-version: "3.8" # Minimum of PYVERSIONS, but at least 3.8
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
+
+      - name: "Install dependencies"
+        run: |
+          # We run on 3.8, but the pins were made on 3.7, so don't insist on
+          # hashes, which won't match.
+          python -m pip install -r requirements/tox.pip
+
+      - name: "Tox mypy"
+        run: |
+          python -m tox -e mypy
+
   doc:
     name: "Build docs"
     runs-on: ubuntu-latest