Add pytype as one of our sanity tests

.gitignore

@@ -22,6 +22,8 @@ py3[0-9]_native/
 a.out
 src/python/grpcio_*/LICENSE
 src/python/grpcio_status/grpc_status/google/rpc/status.proto
+None
+.pytype
 
 # Node installation output
 node_modules

tools/run_tests/sanity/check_pytype.sh

@@ -0,0 +1,8 @@
+#! /bin/bash -ex
+
+JOBS=`nproc` || JOBS=4
+python3 -m pip install pytype==2019.11.27
+
+for dir in src/python/grpcio*; do
+    python3 -m pytype --keep-going -j "$JOBS" --strict-import $dir
+done

tools/run_tests/sanity/sanity_tests.yaml

@@ -6,6 +6,7 @@
 - script: tools/run_tests/sanity/check_deprecated_grpc++.py
 - script: tools/run_tests/sanity/check_owners.sh
 - script: tools/run_tests/sanity/check_port_platform.py
+- script: tools/run_tests/sanity/check_pytype.sh
 - script: tools/run_tests/sanity/check_qps_scenario_changes.py
 - script: tools/run_tests/sanity/check_shellcheck.sh
 - script: tools/run_tests/sanity/check_submodules.sh