fix: improve type hints, mypy check (#242)

* chore: ensure mypy passes

* 🦉 Updates from OwlBot

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* chore: flake8 doesn't like lambdas

* test: add mypy test scenarioa

* 🦉 Updates from OwlBot

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* chore: scope mypy to google.cloud.datastore for now

* chore: remove api_core ignores, quiet a mypy error by import rename

* fix: drop unneded extra function

Also, have shim 'make_datastore_api' raise an exception, as it only
gets called if gRPC is disabled, or not installed.

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: Tres Seaver <tseaver@palladion.com>

google/cloud/datastore/_http.py

@@ -14,10 +14,10 @@
 
 """Connections to Google Cloud Datastore API servers."""
 
-from google.rpc import status_pb2
+from google.rpc import status_pb2  # type: ignore
 
 from google.cloud import _http as connection_module
-from google.cloud import exceptions
+from google.cloud import exceptions  # type: ignore
 from google.cloud.datastore_v1.types import datastore as _datastore_pb2
 
 

google/cloud/datastore/client.py

@@ -17,10 +17,10 @@
 import warnings
 
 import google.api_core.client_options
-from google.auth.credentials import AnonymousCredentials
-from google.cloud._helpers import _LocalStack
-from google.cloud._helpers import _determine_default_project as _base_default_project
-from google.cloud.client import ClientWithProject
+from google.auth.credentials import AnonymousCredentials  # type: ignore
+from google.cloud._helpers import _LocalStack  # type: ignore
+from google.cloud._helpers import _determine_default_project as _base_default_project  # type: ignore
+from google.cloud.client import ClientWithProject  # type: ignore
 from google.cloud.datastore.version import __version__
 from google.cloud.datastore import helpers
 from google.cloud.datastore._http import HTTPDatastoreAPI
@@ -32,13 +32,14 @@
 
 try:
     from google.cloud.datastore._gapic import make_datastore_api
-
 except ImportError:  # pragma: NO COVER
-    from google.api_core import client_info
+    from google.api_core import client_info as api_core_client_info
+
+    def make_datastore_api(client):
+        raise RuntimeError("No gRPC available")
 
-    make_datastore_api = None
     _HAVE_GRPC = False
-    _CLIENT_INFO = client_info.ClientInfo(client_library_version=__version__)
+    _CLIENT_INFO = api_core_client_info.ClientInfo(client_library_version=__version__)
 else:
     from google.api_core.gapic_v1 import client_info
 

mypy.ini

@@ -0,0 +1,7 @@
+[mypy]
+python_version = 3.6
+namespace_packages = True
+ignore_missing_imports = True
+
+[mypy-google.protobuf]
+ignore_missing_imports = True

noxfile.py

@@ -37,6 +37,7 @@
 nox.options.sessions = [
     "unit",
     "system",
+    "mypy",
     "cover",
     "lint",
     "lint_setup_py",
@@ -72,6 +73,15 @@ def blacken(session):
     )
 
 
+@nox.session(python=DEFAULT_PYTHON_VERSION)
+def mypy(session):
+    """Verify type hints are mypy compatible."""
+    session.install("-e", ".")
+    session.install("mypy")
+    # TODO: also verify types on tests, all of google package
+    session.run("mypy", "-p", "google.cloud.datastore", "--no-incremental")
+
+
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""

owlbot.py

@@ -200,4 +200,37 @@ def docfx(session):
 """,
 )
 
+# add type checker nox session
+s.replace("noxfile.py",
+    """nox.options.sessions = \[
+    "unit",
+    "system",""",
+    """nox.options.sessions = [
+    "unit",
+    "system",
+    "mypy",""",
+)
+
+
+s.replace(
+    "noxfile.py",
+    """\
+@nox.session\(python=DEFAULT_PYTHON_VERSION\)
+def lint_setup_py\(session\):
+""",
+    '''\
+@nox.session(python=DEFAULT_PYTHON_VERSION)
+def mypy(session):
+    """Verify type hints are mypy compatible."""
+    session.install("-e", ".")
+    session.install("mypy")
+    # TODO: also verify types on tests, all of google package
+    session.run("mypy", "-p", "google.cloud.datastore", "--no-incremental")
+
+
+@nox.session(python=DEFAULT_PYTHON_VERSION)
+def lint_setup_py(session):
+''',
+)
+
 s.shell.run(["nox", "-s", "blacken"], hide_output=False)