👷 Run mypy from within tox

…to resolve dependencies.

Driv-by: Run `system` tests from within `mypy`, as creating an
additional container considered too waistful for now.

.gitlab-ci.yml

@@ -28,8 +28,8 @@ flake8:
 mypy:
   stage: lint
   script:
-    - pip3 install mypy importlib_metadata
-    - cd src && mypy -p dnstemple
+    - pip3 install tox
+    - tox -e mypy,system
 
 # unit
 unit:

Makefile

@@ -14,7 +14,7 @@ pypi:	distribution-package test
 test:	tests
 tests:
 	flake8
-	cd src && mypy -p dnstemple
+	tox
 	${MAKE} -C sample test
 
 .PHONY: python-package distribution-package pypi tests test

tox.ini

@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py36, py37, py38, py39, py310, pypy3, system
+envlist = mypy, py36, py37, py38, py39, py310, pypy3, system
 isolated_build = True
 
 [testenv]
@@ -28,11 +28,22 @@ deps =
 commands =
     pytest --cov
 
+[testenv:mypy]
+deps =
+    mypy
+    importlib_metadata
+    dnspython
+    PyYAML
+    types-PyYAML
+allowlist_externals = sh
+commands =
+    sh -c "cd src && mypy -p dnstemple"
+
 [testenv:system]
 deps =
     importlib_metadata
     dnspython
     PyYAML
 allowlist_externals = make
 commands =
-    make test
+    make -C sample test