diff --git a/noxfile.py b/noxfile.py
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+++ b/noxfile.py
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+# Copyright 2019 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import nox
+
+TEST_DEPENDENCIES = [
+    "flask",
+    "mock",
+    "oauth2client",
+    "pytest",
+    "pytest-cov",
+    "pytest-localserver",
+    "requests",
+    "urllib3",
+    "cryptography",
+    "grpcio",
+]
+BLACK_VERSION = "black==19.3b0"
+BLACK_PATHS = ["google", "tests", "noxfile.py", "setup.py", "docs/conf.py"]
+
+
+@nox.session(python="3.7")
+def lint(session):
+    session.install("flake8", "flake8-import-order", "docutils", BLACK_VERSION)
+    session.install(".")
+    session.run("black", "--check", *BLACK_PATHS)
+    session.run(
+        "flake8",
+        "--import-order-style=google",
+        "--application-import-names=google,tests,system_tests",
+        "google",
+        "tests",
+    )
+    session.run(
+        "python", "setup.py", "check", "--metadata", "--restructuredtext", "--strict"
+    )
+
+
+@nox.session(python="3.6")
+def blacken(session):
+    """Run black.
+
+    Format code to uniform standard.
+
+    This currently uses Python 3.6 due to the automated Kokoro run of synthtool.
+    That run uses an image that doesn't have 3.6 installed. Before updating this
+    check the state of the `gcp_ubuntu_config` we use for that Kokoro run.
+    """
+    session.install(BLACK_VERSION)
+    session.run("black", *BLACK_PATHS)
+
+
+@nox.session(python=["2.7", "3.5", "3.6", "3.7"])
+def unit(session):
+    session.install(*TEST_DEPENDENCIES)
+    session.install(".")
+    session.run(
+        "pytest", "--cov=google.auth", "--cov=google.oauth2", "--cov=tests", "tests"
+    )
+
+
+@nox.session(python="3.7")
+def cover(session):
+    session.install(*TEST_DEPENDENCIES)
+    session.install(".")
+    session.run(
+        "pytest",
+        "--cov=google.auth",
+        "--cov=google.oauth2",
+        "--cov=tests",
+        "--cov-report=",
+        "tests",
+    )
+    session.run("coverage", "report", "--show-missing", "--fail-under=100")
+
+
+@nox.session(python="3.7")
+def docgen(session):
+    session.env["SPHINX_APIDOC_OPTIONS"] = "members,inherited-members,show-inheritance"
+    session.install(*TEST_DEPENDENCIES)
+    session.install("sphinx")
+    session.install(".")
+    session.run("rm", "-r", "docs/reference")
+    session.run(
+        "sphinx-apidoc",
+        "--output-dir",
+        "docs/reference",
+        "--separate",
+        "--module-first",
+        "google",
+    )
+
+
+@nox.session(python="3.7")
+def docs(session):
+    session.install("sphinx", "-r", "docs/requirements-docs.txt")
+    session.install(".")
+    session.run("make", "-C", "docs", "html")
+
+
+@nox.session(python="pypy")
+def pypy(session):
+    session.install(*TEST_DEPENDENCIES)
+    session.install(".")
+    session.run(
+        "pytest", "--cov=google.auth", "--cov=google.oauth2", "--cov=tests", "tests"
+    )