Run mypy in pre-commit (#190)

Author: sloria

.pre-commit-config.yaml

@@ -19,3 +19,12 @@ repos:
   hooks:
   - id: blacken-docs
     additional_dependencies: [black==20.8b1]
+# Use a local hook to run because the official hook runs mypy in a venv
+# that doesn't have dependencies or their type annotations installed.
+- repo: local
+  hooks:
+    - id: mypy
+      name: mypy
+      entry: mypy
+      language: system
+      types: [python]

tox.ini

@@ -15,9 +15,6 @@ commands = pytest {posargs}
 extras = lint
 commands =
     pre-commit run --all-files
-    ; Run mypy outside pre-commit because pre-commit runs mypy in a venv
-    ; that doesn't have dependencies or their type annotations installed.
-    mypy .
 
 ; Below tasks are for development only (not run in CI)