Run mypy in GitHub CI

Author: jelmer

.github/workflows/test.yml

@@ -44,6 +44,10 @@ jobs:
         run: |
           python -m ruff format --check .
 
+      - name: Type Check
+        run: |
+          python -m mypy testtools
+
       - name: Tests
         run: |
           python -W once -m testtools.run testtools.tests.test_suite

pyproject.toml

@@ -35,7 +35,10 @@ Homepage = "https://github.com/testing-cabal/testtools"
 [project.optional-dependencies]
 test = ["testscenarios", "testresources"]
 twisted = ["Twisted", "fixtures"]
-dev = ["ruff==0.14.4"]
+dev = [
+	"ruff==0.14.4",
+	"mypy>=1.0.0",
+]
 
 [tool.hatch.version]
 source = "vcs"