Add mypy to the project

.github/matchers/mypy.json

@@ -0,0 +1,15 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "mypy",
+      "pattern": [
+        {
+          "regexp": "^([^:]+):(\\d+): error: (.+)$",
+          "file": 1,
+          "line": 2,
+          "message": 3
+        }
+      ]
+    }
+  ]
+}

.github/workflows/linting.yaml

@@ -10,9 +10,6 @@ on:
       - devel
       - master
 
-env:
-  NO_COLORS: true
-
 jobs:
   setup:
     runs-on: ubuntu-22.04
@@ -49,9 +46,13 @@ jobs:
         run: |
           poetry install
       - name: Run tests
+        env:
+          NO_COLORS: true
         run: |
+          echo "::add-matcher::.github/matchers/mypy.json"
           echo "::add-matcher::.github/matchers/ruff.json"
           echo "::add-matcher::.github/matchers/unbehead.json"
           poetry run -- make lint --keep-going
           echo "::remove-matcher owner=unbehead::"
           echo "::remove-matcher owner=ruff::"
+          echo "::remove-matcher owner=mypy::"

.gitignore

@@ -5,6 +5,7 @@
 dist/
 
 # temporary directories
+.mypy_cache/
 .pytest_cache/
 .ruff_cache/
 __pycache__/

.mypy.ini

@@ -0,0 +1,2 @@
+[mypy]
+exclude = tests/

Makefile

@@ -1,5 +1,11 @@
 # -- linting -------------------------------------------------------------------
 
+.PHONY: mypy
+mypy:
+	# FIXME: Remove flag once it's possible to disable color via envvar.
+	#        The uncolored output is necessary on CI for the matcher to work.
+	mypy . --no-color-output
+
 .PHONY: ruff
 ruff:
 	ruff check .
@@ -9,7 +15,7 @@ unbehead:
 	unbehead --check
 
 .PHONY: lint
-lint: ruff unbehead
+lint: mypy ruff unbehead
 
 # -- testing -------------------------------------------------------------------
 

pyproject.toml

@@ -34,8 +34,10 @@ pyyaml = ">=6"
 click = ">=8"
 
 [tool.poetry.group.dev.dependencies]
+mypy = "^1.5.1"
 pytest = "^7.4.0"
 ruff = "^0.0.280"
+types-pyyaml = "^6.0.12.11"
 
 [build-system]
 requires = ["poetry-core"]