Add pytype nox session

.gitignore

@@ -29,6 +29,7 @@ pip-log.txt
 .nox
 .cache
 .pytest_cache
+.pytype
 
 
 # Mac

noxfile.py

@@ -27,6 +27,8 @@
 BLACK_VERSION = "black==19.10b0"
 BLACK_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
+PYTYPE_VERSION = "pytype==2021.4.9"
+
 DEFAULT_PYTHON_VERSION = "3.8"
 SYSTEM_TEST_PYTHON_VERSIONS = ["3.8"]
 UNIT_TEST_PYTHON_VERSIONS = ["3.6", "3.7", "3.8", "3.9"]
@@ -41,13 +43,22 @@
     "lint",
     "lint_setup_py",
     "blacken",
+    "pytype",
     "docs",
 ]
 
 # Error if a python version is missing
 nox.options.error_on_missing_interpreters = True
 
 
+@nox.session(python=DEFAULT_PYTHON_VERSION)
+def pytype(session):
+    """Run type checks."""
+    session.install("-e", ".[all]")
+    session.install(PYTYPE_VERSION)
+    session.run("pytype")
+
+
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def lint(session):
     """Run linters.

owlbot.py

@@ -351,4 +351,60 @@
 # ----------------------------------------------------------------------------
 python.py_samples()
 
+# ----------------------------------------------------------------------------
+# pytype-related changes
+# ----------------------------------------------------------------------------
+
+# Add .pytype to .gitignore
+s.replace(".gitignore", r"\.pytest_cache", "\g<0>\n.pytype")
+
+# Add pytype config to setup.cfg
+s.replace(
+    "setup.cfg",
+    r"universal = 1",
+    textwrap.dedent(
+        """    \g<0>
+
+    [pytype]
+    python_version = 3.8
+    inputs =
+        google/cloud/
+    exclude =
+        tests/
+        google/pubsub_v1/  # generated code
+    output = .pytype/
+    disable =
+        # There's some issue with finding some pyi files, thus disabling.
+        # The issue https://github.com/google/pytype/issues/150 is closed, but the
+        # error still occurs for some reason.
+        pyi-error"""
+    ),
+)
+
+# Add pytype session to noxfile.py
+s.replace(
+    "noxfile.py",
+    r"BLACK_PATHS = \[.*?\]",
+    '\g<0>\n\nPYTYPE_VERSION = "pytype==2021.4.9"\n',
+)
+s.replace(
+    "noxfile.py", r'"blacken",', '\g<0>\n    "pytype",',
+)
+s.replace(
+    "noxfile.py",
+    r"nox\.options\.error_on_missing_interpreters = True",
+    textwrap.dedent(
+        '''    \g<0>
+
+
+    @nox.session(python=DEFAULT_PYTHON_VERSION)
+    def pytype(session):
+        """Run type checks."""
+        session.install("-e", ".[all]")
+        session.install(PYTYPE_VERSION)
+        session.run("pytype")'''
+    ),
+)
+
+
 s.shell.run(["nox", "-s", "blacken"], hide_output=False)

setup.cfg

@@ -17,3 +17,17 @@
 # Generated by synthtool. DO NOT EDIT!
 [bdist_wheel]
 universal = 1
+
+[pytype]
+python_version = 3.8
+inputs =
+    google/cloud/
+exclude =
+    tests/
+    google/pubsub_v1/  # generated code
+output = .pytype/
+disable =
+    # There's some issue with finding some pyi files, thus disabling.
+    # The issue https://github.com/google/pytype/issues/150 is closed, but the
+    # error still occurs for some reason.
+    pyi-error