Type checking

.travis.yml

@@ -10,6 +10,8 @@ matrix:
  env: TOXENV=py38
  - python: 3.8
  env: TOXENV=flake8
+ - python: 3.8
+ env: TOXENV=mypy
  - python: 3.8
  env: TOXENV=dist
  - python: 3.8

MANIFEST.in

@@ -5,6 +5,7 @@ include requirements-dev.txt
 include *.md
 include .bumpversion.cfg
 include tox.ini
+include mypy.ini
 include pyproject.toml
 
 # Code and test files

mypy.ini

@@ -0,0 +1,24 @@
+# Global options:
+
+[mypy]
+python_version = 3.6
+
+# Per-module options:
+
+[mypy-ipython_genutils.*]
+ignore_missing_imports = True
+
+[mypy-nbformat.*]
+ignore_missing_imports = True
+
+[mypy-nest_asyncio.*]
+ignore_missing_imports = True
+
+[mypy-async_generator.*]
+ignore_missing_imports = True
+
+[mypy-traitlets.*]
+ignore_missing_imports = True
+
+[mypy-jupyter_client.*]
+ignore_missing_imports = True

nbclient/__init__.py

@@ -4,7 +4,7 @@
 from ._version import version as __version__ # noqa: F401
 
 
-def _cleanup():
+def _cleanup() -> None:
  pass