Check types in travis (#3024)

* lint mypy typing

* dot

* revert autoformat

* allow failures for typing

.travis.yml

@@ -21,6 +21,7 @@ matrix:
   - env: CONDA_ENV=py36-zarr-dev
   - env: CONDA_ENV=docs
   - env: CONDA_ENV=lint
+  - env: CONDA_ENV=typing
   - env: CONDA_ENV=py36-hypothesis
 
   allow_failures:
@@ -30,6 +31,7 @@ matrix:
     - EXTRA_FLAGS="--run-flaky --run-network-tests"
   - env: CONDA_ENV=py36-pandas-dev
   - env: CONDA_ENV=py36-zarr-dev
+  - env: CONDA_ENV=typing
 
 before_install:
   - wget https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86_64.sh -O miniconda.sh;
@@ -40,9 +42,10 @@ before_install:
   - conda info -a
 
 install:
-  - if [[ "$CONDA_ENV" == "docs" ]]; then
+  - |
+    if [[ "$CONDA_ENV" == "docs" ]]; then
       conda env create -n test_env --file doc/environment.yml;
-    elif [[ "$CONDA_ENV" == "lint" ]]; then
+    elif [[ "$CONDA_ENV" == "lint" ]] || [[ "$CONDA_ENV" == "typing" ]] ; then
       conda env create -n test_env --file ci/requirements-py37.yml;
     else
       conda env create -n test_env --file ci/requirements-$CONDA_ENV.yml;
@@ -56,11 +59,14 @@ script:
   - which python
   - python --version
   - python -OO -c "import xarray"
-  - if [[ "$CONDA_ENV" == "docs" ]]; then
+  - |
+    if [[ "$CONDA_ENV" == "docs" ]]; then
       cd doc;
       sphinx-build -n -j auto -b html -d _build/doctrees . _build/html;
     elif [[ "$CONDA_ENV" == "lint" ]]; then
       flake8 ;
+    elif [[ "$CONDA_ENV" == "typing" ]]; then
+      mypy . ;
     elif [[ "$CONDA_ENV" == "py36-hypothesis" ]]; then
       pytest properties ;
     else

setup.cfg

@@ -34,6 +34,8 @@ known_first_party=xarray
 multi_line_output=4
 
 # Most of the numerical computing stack doesn't have type annotations yet.
+[mypy-affine.*]
+ignore_missing_imports = True
 [mypy-bottleneck.*]
 ignore_missing_imports = True
 [mypy-cdms2.*]
@@ -85,6 +87,12 @@ ignore_missing_imports = True
 [mypy-zarr.*]
 ignore_missing_imports = True
 
+# setuptools is not typed
+[mypy-setup]
+ignore_errors = True
+# versioneer code
+[mypy-versioneer.*]
+ignore_errors = True
 # written by versioneer
 [mypy-xarray._version]
 ignore_errors = True