From 2982dd3d565923509bab210eb45b800ce464fe8a Mon Sep 17 00:00:00 2001
From: Bu Sun Kim <8822365+busunkim96@users.noreply.github.com>
Date: Wed, 10 Oct 2018 11:04:44 -0700
Subject: [PATCH] Use new Nox (#6175)

---
 .kokoro/build.sh                             |  9 +++-
 api_core/{nox.py => noxfile.py}              | 39 +++-----------
 asset/{nox.py => noxfile.py}                 | 25 +++------
 automl/{nox.py => noxfile.py}                | 31 ++++-------
 bigquery/{nox.py => noxfile.py}              | 54 +++++---------------
 bigquery_datatransfer/{nox.py => noxfile.py} | 23 ++-------
 bigtable/{nox.py => noxfile.py}              | 36 +++----------
 container/{nox.py => noxfile.py}             | 31 +++--------
 core/{nox.py => noxfile.py}                  | 31 +++--------
 dataproc/{nox.py => noxfile.py}              | 22 ++------
 datastore/{nox.py => noxfile.py}             | 47 +++++------------
 dlp/{nox.py => noxfile.py}                   | 30 +++--------
 dns/{nox.py => noxfile.py}                   | 24 ++-------
 error_reporting/{nox.py => noxfile.py}       | 36 +++----------
 firestore/{nox.py => noxfile.py}             | 36 +++----------
 iot/{nox.py => noxfile.py}                   | 36 ++++---------
 tasks/nox.py => kms/noxfile.py               | 26 +++-------
 language/{nox.py => noxfile.py}              | 37 +++-----------
 logging/{nox.py => noxfile.py}               | 49 ++++--------------
 monitoring/{nox.py => noxfile.py}            | 37 +++-----------
 oslogin/{nox.py => noxfile.py}               | 25 +++------
 pubsub/{nox.py => noxfile.py}                | 41 +++------------
 redis/{nox.py => noxfile.py}                 | 31 ++---------
 resource_manager/{nox.py => noxfile.py}      | 26 ++--------
 runtimeconfig/{nox.py => noxfile.py}         | 31 ++---------
 spanner/{nox.py => noxfile.py}               | 44 +++-------------
 speech/{nox.py => noxfile.py}                | 36 +++----------
 storage/{nox.py => noxfile.py}               | 36 +++----------
 kms/nox.py => tasks/noxfile.py               | 23 ++-------
 texttospeech/{nox.py => noxfile.py}          | 24 ++-------
 trace/{nox.py => noxfile.py}                 | 22 ++------
 translate/{nox.py => noxfile.py}             | 45 +++-------------
 videointelligence/{nox.py => noxfile.py}     | 36 ++++---------
 vision/{nox.py => noxfile.py}                | 37 +++-----------
 websecurityscanner/{nox.py => noxfile.py}    | 25 ++-------
 35 files changed, 248 insertions(+), 893 deletions(-)
 rename api_core/{nox.py => noxfile.py} (77%)
 rename asset/{nox.py => noxfile.py} (74%)
 rename automl/{nox.py => noxfile.py} (58%)
 rename bigquery/{nox.py => noxfile.py} (79%)
 rename bigquery_datatransfer/{nox.py => noxfile.py} (82%)
 rename bigtable/{nox.py => noxfile.py} (80%)
 rename container/{nox.py => noxfile.py} (82%)
 rename core/{nox.py => noxfile.py} (81%)
 rename dataproc/{nox.py => noxfile.py} (84%)
 rename datastore/{nox.py => noxfile.py} (83%)
 rename dlp/{nox.py => noxfile.py} (81%)
 rename dns/{nox.py => noxfile.py} (82%)
 rename error_reporting/{nox.py => noxfile.py} (80%)
 rename firestore/{nox.py => noxfile.py} (80%)
 rename iot/{nox.py => noxfile.py} (71%)
 rename tasks/nox.py => kms/noxfile.py (74%)
 rename language/{nox.py => noxfile.py} (80%)
 rename logging/{nox.py => noxfile.py} (75%)
 rename monitoring/{nox.py => noxfile.py} (80%)
 rename oslogin/{nox.py => noxfile.py} (73%)
 rename pubsub/{nox.py => noxfile.py} (75%)
 rename redis/{nox.py => noxfile.py} (74%)
 rename resource_manager/{nox.py => noxfile.py} (81%)
 rename runtimeconfig/{nox.py => noxfile.py} (74%)
 rename spanner/{nox.py => noxfile.py} (74%)
 rename speech/{nox.py => noxfile.py} (79%)
 rename storage/{nox.py => noxfile.py} (80%)
 rename kms/nox.py => tasks/noxfile.py (74%)
 rename texttospeech/{nox.py => noxfile.py} (73%)
 rename trace/{nox.py => noxfile.py} (84%)
 rename translate/{nox.py => noxfile.py} (73%)
 rename videointelligence/{nox.py => noxfile.py} (71%)
 rename vision/{nox.py => noxfile.py} (79%)
 rename websecurityscanner/{nox.py => noxfile.py} (81%)

diff --git a/.kokoro/build.sh b/.kokoro/build.sh
index 3d5347b0042e..39634b7d6d52 100755
--- a/.kokoro/build.sh
+++ b/.kokoro/build.sh
@@ -46,6 +46,11 @@ fi
 
 cd "$PACKAGE"
 
-python3.6 -m pip install --quiet nox-automation
+# Remove old nox
+python3.6 -m pip uninstall --yes --quiet nox-automation
 
-nox
+# Install nox
+python3.6 -m pip install --upgrade --quiet nox
+python3.6 -m nox --version
+
+python3.6 -m nox
diff --git a/api_core/nox.py b/api_core/noxfile.py
similarity index 77%
rename from api_core/nox.py
rename to api_core/noxfile.py
index 7d14ad9befb1..77ef2cec9327 100644
--- a/api_core/nox.py
+++ b/api_core/noxfile.py
@@ -19,7 +19,6 @@
 import nox  # pytype: disable=import-error
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -52,57 +51,37 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit_grpc_gcp(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit_grpc_gcp(session):
     """Run the unit test suite with grpcio-gcp installed."""
 
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-grpc-gcp-' + py
-
     # Install grpcio-gcp
     session.install('grpcio-gcp')
 
     default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', 'flake8-import-order')
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'Pygments')
     session.run(
@@ -111,10 +90,9 @@ def lint_setup_py(session):
 
 # No 2.7 due to https://github.com/google/importlab/issues/26.
 # No 3.7 because pytype supports up to 3.6 only.
-@nox.session
+@nox.session(python='3.6')
 def pytype(session):
   """Run type-checking."""
-  session.interpreter = 'python3.6'
   session.install('.',
                   'grpcio >= 1.8.2',
                   'grpcio-gcp >= 0.2.2',
@@ -122,14 +100,13 @@ def pytype(session):
   session.run('pytype')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/asset/nox.py b/asset/noxfile.py
similarity index 74%
rename from asset/nox.py
rename to asset/noxfile.py
index 884edf60d671..a3ed016336e6 100644
--- a/asset/nox.py
+++ b/asset/noxfile.py
@@ -19,24 +19,7 @@
 
 import nox
 
-
-@nox.session
 def default(session):
-    return unit(session, 'default')
-
-
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
-
     # Install all test dependencies, then install this package in-place.
     session.install('pytest')
     session.install('-e', '.')
@@ -45,10 +28,14 @@ def unit(session, py):
     session.run('py.test', '--quiet', os.path.join('tests', 'unit'))
 
 
-@nox.session
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Run the unit test suite."""
+    default(session)
+
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/automl/nox.py b/automl/noxfile.py
similarity index 58%
rename from automl/nox.py
rename to automl/noxfile.py
index 58f8c2b507ce..8277b35f8a35 100644
--- a/automl/nox.py
+++ b/automl/noxfile.py
@@ -18,35 +18,24 @@
 import nox
 
 
-@nox.session
 def default(session):
-    return unit(session, 'default')
+  # Install all test dependencies, then install this package in-place.
+  session.install('pytest')
+  session.install('-e', '.')
 
+  # Run py.test against the unit tests.
+  session.run('py.test', '--quiet', os.path.join('tests', 'unit'))
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
 
-    # Install all test dependencies, then install this package in-place.
-    session.install('pytest')
-    session.install('-e', '.')
-
-    # Run py.test against the unit tests.
-    session.run('py.test', '--quiet', os.path.join('tests', 'unit'))
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Run the unit test suite."""
+    default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/bigquery/nox.py b/bigquery/noxfile.py
similarity index 79%
rename from bigquery/nox.py
rename to bigquery/noxfile.py
index 902b6e663633..21b8487039cc 100644
--- a/bigquery/nox.py
+++ b/bigquery/noxfile.py
@@ -25,7 +25,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -40,14 +39,14 @@ def default(session):
         session.install('-e', local_dep)
 
     # Pyarrow does not support Python 3.7
-    if session.interpreter == 'python3.7':
+    if session.python == '3.7':
         dev_install = '.[pandas]'
     else:
         dev_install = '.[pandas, pyarrow]'
     session.install('-e', dev_install)
 
     # IPython does not support Python 2 after version 5.x
-    if session.interpreter == 'python2.7':
+    if session.python == '2.7':
         session.install('ipython==5.5')
     else:
         session.install('ipython')
@@ -67,35 +66,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -108,7 +92,7 @@ def system(session, py):
     session.install('-e', '.[pandas]')
 
     # IPython does not support Python 2 after version 5.x
-    if session.interpreter == 'python2.7':
+    if session.python == '2.7':
         session.install('ipython==5.5')
     else:
         session.install('ipython')
@@ -122,21 +106,14 @@ def system(session, py):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def snippets(session, py):
+@nox.session(python=['2.7', '3.6'])
+def snippets(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'snip-' + py
-
     # Install all test dependencies, then install local packages in place.
     session.install('mock', 'pytest')
     for local_dep in LOCAL_DEPS:
@@ -150,14 +127,13 @@ def snippets(session, py):
         'py.test', os.path.join('docs', 'snippets.py'), *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
 
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
@@ -167,28 +143,22 @@ def lint(session):
         'flake8', os.path.join('docs', 'snippets.py'))
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
-
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/bigquery_datatransfer/nox.py b/bigquery_datatransfer/noxfile.py
similarity index 82%
rename from bigquery_datatransfer/nox.py
rename to bigquery_datatransfer/noxfile.py
index 5058fabc8067..fd85b781786b 100644
--- a/bigquery_datatransfer/nox.py
+++ b/bigquery_datatransfer/noxfile.py
@@ -24,7 +24,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -52,40 +51,28 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    session.interpreter = 'python{}'.format(py)
-    session.virtualenv_dirname = 'unit-' + py
     default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
diff --git a/bigtable/nox.py b/bigtable/noxfile.py
similarity index 80%
rename from bigtable/nox.py
rename to bigtable/noxfile.py
index 1e8ce157ee81..28738b0c42fb 100644
--- a/bigtable/nox.py
+++ b/bigtable/noxfile.py
@@ -24,7 +24,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -54,35 +53,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.7'])
-def system(session, py):
+@nox.session(python=['2.7', '3.7'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -98,40 +82,34 @@ def system(session, py):
     session.run('py.test', '--quiet', 'tests/system.py', *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/container/nox.py b/container/noxfile.py
similarity index 82%
rename from container/nox.py
rename to container/noxfile.py
index eb188487182d..37ad9c7cbad1 100644
--- a/container/nox.py
+++ b/container/noxfile.py
@@ -23,17 +23,13 @@
     os.path.join('..', 'api_core'),
 )
 
-
-@nox.session
 def default(session):
     """Default unit test session.
-
     This is intended to be run **without** an interpreter set, so
     that the current ``python`` (on the ``PATH``) or the version of
     Python corresponding to the ``nox`` binary on the ``PATH`` can
     run the tests.
     """
-    # Install all test dependencies, then install local packages in-place.
     session.install('mock', 'pytest', 'pytest-cov')
     for local_dep in LOCAL_DEPS:
         session.install('-e', local_dep)
@@ -53,32 +49,20 @@ def default(session):
         *session.posargs
     )
 
-
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    session.interpreter = 'python{}'.format(py)
-    session.virtualenv_dirname = 'unit-' + py
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Default unit test session."""
+    # Install all test dependencies, then install local packages in-place.
     default(session)
 
-
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -94,10 +78,9 @@ def system(session, py):
     session.run('py.test', '--quiet', 'tests/system/')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/core/nox.py b/core/noxfile.py
similarity index 81%
rename from core/nox.py
rename to core/noxfile.py
index e3d9a1ba701a..b35dbb8732a0 100644
--- a/core/nox.py
+++ b/core/noxfile.py
@@ -22,16 +22,14 @@
     os.path.join('..', 'api_core'),
 )
 
-
-@nox.session
 def default(session):
     """Default unit test session.
-
     This is intended to be run **without** an interpreter set, so
     that the current ``python`` (on the ``PATH``) or the version of
     Python corresponding to the ``nox`` binary the ``PATH`` can
     run the tests.
     """
+
     # Install all test dependencies, then install local packages in-place.
     session.install(
         'mock',
@@ -58,54 +56,39 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Default unit test session."""
     default(session)
 
-
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', 'flake8-import-order')
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/dataproc/nox.py b/dataproc/noxfile.py
similarity index 84%
rename from dataproc/nox.py
rename to dataproc/noxfile.py
index 3d84096895e3..ec3685373a7c 100644
--- a/dataproc/nox.py
+++ b/dataproc/noxfile.py
@@ -24,7 +24,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -52,28 +51,18 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    session.interpreter = 'python{}'.format(py)
-    session.virtualenv_dirname = 'unit-' + py
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.7'])
-def system(session, py):
+@nox.session(python=['2.7', '3.7'])
+def system(session):
     """Run the system test suite."""
 
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
-
-    session.interpreter = 'python{}'.format(py)
-
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -84,10 +73,9 @@ def system(session, py):
                 *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/datastore/nox.py b/datastore/noxfile.py
similarity index 83%
rename from datastore/nox.py
rename to datastore/noxfile.py
index 79d04e1f16ba..39b4eef9c890 100644
--- a/datastore/nox.py
+++ b/datastore/noxfile.py
@@ -25,7 +25,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -55,35 +54,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -98,19 +82,18 @@ def system(session, py):
     session.run('py.test', '--quiet', 'tests/system', *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def doctests(session):
     """Run the system test suite."""
+    # Doctests run against Python 3.6 only.
+    # It is difficult to make doctests run against both Python 2 and Python 3
+    # because they test string output equivalence, which is difficult to
+    # make match (e.g. unicode literals starting with "u").
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Doctests run against Python 3.6 only.
-    # It is difficult to make doctests run against both Python 2 and Python 3
-    # because they test string output equivalence, which is difficult to
-    # make match (e.g. unicode literals starting with "u").
-    session.interpreter = 'python3.6'
 
     # Install all test dependencies, then install this package into the
     # virtualenv's dist-packages.
@@ -124,40 +107,34 @@ def doctests(session):
     session.run('py.test', '--quiet', 'tests/doctests.py')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/dlp/nox.py b/dlp/noxfile.py
similarity index 81%
rename from dlp/nox.py
rename to dlp/noxfile.py
index 76e387099012..31bb3fcb7991 100644
--- a/dlp/nox.py
+++ b/dlp/noxfile.py
@@ -24,7 +24,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Run the unit test suite.
 
@@ -49,32 +48,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
 
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    session.interpreter = 'python{}'.format(py)
-
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -85,36 +72,33 @@ def system(session, py):
                 os.path.join('tests', 'system'), *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.chdir(os.path.dirname(__file__))
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
diff --git a/dns/nox.py b/dns/noxfile.py
similarity index 82%
rename from dns/nox.py
rename to dns/noxfile.py
index e6a578ad4555..8ea0316d29db 100644
--- a/dns/nox.py
+++ b/dns/noxfile.py
@@ -25,7 +25,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -54,54 +53,41 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
 
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/error_reporting/nox.py b/error_reporting/noxfile.py
similarity index 80%
rename from error_reporting/nox.py
rename to error_reporting/noxfile.py
index f968977ece32..909559610370 100644
--- a/error_reporting/nox.py
+++ b/error_reporting/noxfile.py
@@ -26,7 +26,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -55,61 +54,41 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
 
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -124,14 +103,13 @@ def system(session, py):
     session.run('py.test', '-vvv', 'tests/system', *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/firestore/nox.py b/firestore/noxfile.py
similarity index 80%
rename from firestore/nox.py
rename to firestore/noxfile.py
index 6b0dd65952ab..064f8044f182 100644
--- a/firestore/nox.py
+++ b/firestore/noxfile.py
@@ -26,7 +26,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -57,34 +56,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
 
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('FIRESTORE_APPLICATION_CREDENTIALS'):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -103,40 +88,33 @@ def system(session, py):
     )
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.chdir(os.path.dirname(__file__))
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
diff --git a/iot/nox.py b/iot/noxfile.py
similarity index 71%
rename from iot/nox.py
rename to iot/noxfile.py
index e7eebe585f33..2ce4269a0a93 100644
--- a/iot/nox.py
+++ b/iot/noxfile.py
@@ -18,23 +18,7 @@
 import nox
 
 
-@nox.session
 def default(session):
-    return unit(session, 'default')
-
-
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
-
     # Install all test dependencies, then install this package in-place.
     session.install('pytest')
     session.install('-e', '.')
@@ -43,21 +27,20 @@ def unit(session, py):
     session.run('py.test', '--quiet', os.path.join('tests', 'unit'))
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.7'])
-def system(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Run the unit test suite."""
+    default(session)
+
+
+@nox.session(python=['2.7', '3.7'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Install all test dependencies, then install this package in-place.
     session.install('pytest')
     session.install('-e', '.')
@@ -67,10 +50,9 @@ def system(session, py):
                 *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/tasks/nox.py b/kms/noxfile.py
similarity index 74%
rename from tasks/nox.py
rename to kms/noxfile.py
index 884edf60d671..6f269e97eb5e 100644
--- a/tasks/nox.py
+++ b/kms/noxfile.py
@@ -20,23 +20,7 @@
 import nox
 
 
-@nox.session
 def default(session):
-    return unit(session, 'default')
-
-
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
-
     # Install all test dependencies, then install this package in-place.
     session.install('pytest')
     session.install('-e', '.')
@@ -45,10 +29,16 @@ def unit(session, py):
     session.run('py.test', '--quiet', os.path.join('tests', 'unit'))
 
 
-@nox.session
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Run the unit test suite."""
+    default(session)
+
+
+
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/language/nox.py b/language/noxfile.py
similarity index 80%
rename from language/nox.py
rename to language/noxfile.py
index 9ea66d4a737c..a8fe8c5ac081 100644
--- a/language/nox.py
+++ b/language/noxfile.py
@@ -25,7 +25,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -54,35 +53,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -98,40 +82,33 @@ def system(session, py):
     session.run('py.test', '--quiet', 'tests/system/')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/logging/nox.py b/logging/noxfile.py
similarity index 75%
rename from logging/nox.py
rename to logging/noxfile.py
index 3ac0c3c9e217..dfc477e5d7dd 100644
--- a/logging/nox.py
+++ b/logging/noxfile.py
@@ -34,22 +34,13 @@
 )
 
 
-@nox.session
 def default(session, django_dep=('django',)):
     """Default unit test session.
-
-    This is intended to be run **without** an interpreter set, so
-    that the current ``python`` (on the ``PATH``) or the version of
-    Python corresponding to the ``nox`` binary the ``PATH`` can
-    run the tests.
     """
+  
     # Install all test dependencies, then install this package in-place.
     deps = UNIT_TEST_DEPS
-
-    if session.interpreter is None and sys.version_info[:2] == (2, 7):
-        deps += ('django >= 1.11.0, < 2.0.0dev',)
-    else:
-        deps += django_dep
+    deps += django_dep
 
     session.install(*deps)
     for local_dep in LOCAL_DEPS:
@@ -71,17 +62,10 @@ def default(session, django_dep=('django',)):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
 
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     # Testing multiple version of django
     # See https://www.djangoproject.com/download/ for supported version
     django_deps_27 = [
@@ -89,27 +73,20 @@ def unit(session, py):
         ('django >= 1.11.0, < 2.0.0dev',),
     ]
 
-    if session.interpreter == 'python2.7':
+    if session.virtualenv.interpreter == '2.7':
         [default(session, django_dep=django) for django in django_deps_27]
     else:
         default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -137,40 +114,34 @@ def system(session, py):
         *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/monitoring/nox.py b/monitoring/noxfile.py
similarity index 80%
rename from monitoring/nox.py
rename to monitoring/noxfile.py
index 045ddd9ecf9b..53ec4eff8f45 100644
--- a/monitoring/nox.py
+++ b/monitoring/noxfile.py
@@ -24,7 +24,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -54,35 +53,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.7'])
-def system(session, py):
+@nox.session(python=['2.7', '3.7'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -98,40 +82,33 @@ def system(session, py):
     session.run('py.test', '--quiet', 'tests/system', *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/oslogin/nox.py b/oslogin/noxfile.py
similarity index 73%
rename from oslogin/nox.py
rename to oslogin/noxfile.py
index 58f8c2b507ce..1b66d8b23018 100644
--- a/oslogin/nox.py
+++ b/oslogin/noxfile.py
@@ -18,23 +18,7 @@
 import nox
 
 
-@nox.session
 def default(session):
-    return unit(session, 'default')
-
-
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
-
     # Install all test dependencies, then install this package in-place.
     session.install('pytest')
     session.install('-e', '.')
@@ -43,10 +27,15 @@ def unit(session, py):
     session.run('py.test', '--quiet', os.path.join('tests', 'unit'))
 
 
-@nox.session
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Run the unit test suite."""
+    default(session)
+
+
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/pubsub/nox.py b/pubsub/noxfile.py
similarity index 75%
rename from pubsub/nox.py
rename to pubsub/noxfile.py
index fc887cadfdc8..a061653d5407 100644
--- a/pubsub/nox.py
+++ b/pubsub/noxfile.py
@@ -28,11 +28,6 @@
 @nox.session
 def default(session):
     """Default unit test session.
-
-    This is intended to be run **without** an interpreter set, so
-    that the current ``python`` (on the ``PATH``) or the version of
-    Python corresponding to the ``nox`` binary the ``PATH`` can
-    run the tests.
     """
     # Install all test dependencies, then install local packages in-place.
     session.install('mock', 'pytest', 'pytest-cov')
@@ -54,35 +49,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -102,40 +82,33 @@ def system(session, py):
     )
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/redis/nox.py b/redis/noxfile.py
similarity index 74%
rename from redis/nox.py
rename to redis/noxfile.py
index 964788384a5c..c0a19036996f 100644
--- a/redis/nox.py
+++ b/redis/noxfile.py
@@ -25,14 +25,8 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
-
-    This is intended to be run **without** an interpreter set, so
-    that the current ``python`` (on the ``PATH``) or the version of
-    Python corresponding to the ``nox`` binary the ``PATH`` can
-    run the tests.
     """
     # Install all test dependencies, then install local packages in-place.
     session.install('mock', 'pytest', 'pytest-cov')
@@ -56,54 +50,39 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/resource_manager/nox.py b/resource_manager/noxfile.py
similarity index 81%
rename from resource_manager/nox.py
rename to resource_manager/noxfile.py
index 1610698f6576..35bc9ad5805f 100644
--- a/resource_manager/nox.py
+++ b/resource_manager/noxfile.py
@@ -25,7 +25,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -54,54 +53,39 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/runtimeconfig/nox.py b/runtimeconfig/noxfile.py
similarity index 74%
rename from runtimeconfig/nox.py
rename to runtimeconfig/noxfile.py
index 7899d19c51d5..02dca1406752 100644
--- a/runtimeconfig/nox.py
+++ b/runtimeconfig/noxfile.py
@@ -25,14 +25,8 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
-
-    This is intended to be run **without** an interpreter set, so
-    that the current ``python`` (on the ``PATH``) or the version of
-    Python corresponding to the ``nox`` binary the ``PATH`` can
-    run the tests.
     """
     # Install all test dependencies, then install this package in-place.
     session.install('mock', 'pytest', 'pytest-cov', *LOCAL_DEPS)
@@ -52,54 +46,39 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/spanner/nox.py b/spanner/noxfile.py
similarity index 74%
rename from spanner/nox.py
rename to spanner/noxfile.py
index 7c307b078b05..290d5d17f4bf 100644
--- a/spanner/nox.py
+++ b/spanner/noxfile.py
@@ -25,15 +25,9 @@
 )
 
 
-@nox.session
 def default(session):
-    """Default unit test session.
+    """Default unit test session."""
 
-    This is intended to be run **without** an interpreter set, so
-    that the current ``python`` (on the ``PATH``) or the version of
-    Python corresponding to the ``nox`` binary the ``PATH`` can
-    run the tests.
-    """
     # Install all test dependencies, then install local packages in-place.
     session.install('mock', 'pytest', 'pytest-cov')
     for local_dep in LOCAL_DEPS:
@@ -56,17 +50,9 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.4', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.4', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
@@ -85,58 +71,44 @@ def system_common(session):
     session.run('py.test', '--quiet', 'tests/system', *session.posargs)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     system_common(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/speech/nox.py b/speech/noxfile.py
similarity index 79%
rename from speech/nox.py
rename to speech/noxfile.py
index ee5edd578ef0..264c617cb39b 100644
--- a/speech/nox.py
+++ b/speech/noxfile.py
@@ -24,7 +24,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -50,35 +49,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -92,40 +76,34 @@ def system(session, py):
     session.run('py.test', '--quiet', os.path.join('tests', 'system'))
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.chdir(os.path.dirname(__file__))
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
diff --git a/storage/nox.py b/storage/noxfile.py
similarity index 80%
rename from storage/nox.py
rename to storage/noxfile.py
index de8737970e80..d3a2b93dc117 100644
--- a/storage/nox.py
+++ b/storage/noxfile.py
@@ -55,35 +55,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -104,40 +89,33 @@ def system(session, py):
     session.run('py.test', '--quiet', 'tests/system.py', *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/kms/nox.py b/tasks/noxfile.py
similarity index 74%
rename from kms/nox.py
rename to tasks/noxfile.py
index 884edf60d671..923322a74128 100644
--- a/kms/nox.py
+++ b/tasks/noxfile.py
@@ -20,23 +20,7 @@
 import nox
 
 
-@nox.session
 def default(session):
-    return unit(session, 'default')
-
-
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
-
     # Install all test dependencies, then install this package in-place.
     session.install('pytest')
     session.install('-e', '.')
@@ -44,11 +28,14 @@ def unit(session, py):
     # Run py.test against the unit tests.
     session.run('py.test', '--quiet', os.path.join('tests', 'unit'))
 
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Run the unit test suite."""
+    default(session)
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/texttospeech/nox.py b/texttospeech/noxfile.py
similarity index 73%
rename from texttospeech/nox.py
rename to texttospeech/noxfile.py
index 58f8c2b507ce..e0719dff7a85 100644
--- a/texttospeech/nox.py
+++ b/texttospeech/noxfile.py
@@ -17,24 +17,7 @@
 
 import nox
 
-
-@nox.session
 def default(session):
-    return unit(session, 'default')
-
-
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
-
     # Install all test dependencies, then install this package in-place.
     session.install('pytest')
     session.install('-e', '.')
@@ -42,11 +25,14 @@ def unit(session, py):
     # Run py.test against the unit tests.
     session.run('py.test', '--quiet', os.path.join('tests', 'unit'))
 
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Run the unit test suite."""
+    default(session)
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/trace/nox.py b/trace/noxfile.py
similarity index 84%
rename from trace/nox.py
rename to trace/noxfile.py
index b248b21771a7..d636041905cb 100644
--- a/trace/nox.py
+++ b/trace/noxfile.py
@@ -25,7 +25,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -54,49 +53,38 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/translate/nox.py b/translate/noxfile.py
similarity index 73%
rename from translate/nox.py
rename to translate/noxfile.py
index 0e92e0526cb3..2b5ced7d60cc 100644
--- a/translate/nox.py
+++ b/translate/noxfile.py
@@ -25,15 +25,8 @@
 )
 
 
-@nox.session
 def default(session):
-    """Default unit test session.
-
-    This is intended to be run **without** an interpreter set, so
-    that the current ``python`` (on the ``PATH``) or the version of
-    Python corresponding to the ``nox`` binary the ``PATH`` can
-    run the tests.
-    """
+    """Default unit test session."""
     # Install all test dependencies, then install local packages in-place.
     session.install('mock', 'pytest', 'pytest-cov')
     for local_dep in LOCAL_DEPS:
@@ -49,35 +42,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run the system tests against latest Python 2 and Python 3 only.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -92,40 +70,33 @@ def system(session, py):
     session.run('py.test', '--quiet', 'tests/system.py')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'Pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')
diff --git a/videointelligence/nox.py b/videointelligence/noxfile.py
similarity index 71%
rename from videointelligence/nox.py
rename to videointelligence/noxfile.py
index 0686a1eda886..138a0a07f6a5 100644
--- a/videointelligence/nox.py
+++ b/videointelligence/noxfile.py
@@ -18,23 +18,7 @@
 import nox
 
 
-@nox.session
 def default(session):
-    return unit(session, 'default')
-
-
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
-    """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
-
     # Install all test dependencies, then install this package in-place.
     session.install('pytest')
     session.install('-e', '.')
@@ -43,22 +27,21 @@ def unit(session, py):
     session.run('py.test', '--quiet', os.path.join('tests', 'unit'))
 
 
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
+    """Run the unit test suite."""
+    default(session)
+
+
 # TODO: Fix generated system tests
-#@nox.session
-#@nox.parametrize('py', ['2.7', '3.7'])
-#def system(session, py):
+#@nox.session(python=['2.7', '3.7'])
+#def system(session):
 #    """Run the system test suite."""
 #
 #    # Sanity check: Only run system tests if the environment variable is set.
 #    if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
 #        session.skip('Credentials must be set via environment variable.')
 #
-#    # Run unit tests against all supported versions of Python.
-#    session.interpreter = 'python{}'.format(py)
-#
-#    # Set the virtualenv dirname.
-#    session.virtualenv_dirname = 'sys-' + py
-#
 #    # Install all test dependencies, then install this package in-place.
 #    session.install('pytest')
 #    session.install('-e', '.')
@@ -68,10 +51,9 @@ def unit(session, py):
 #                *session.posargs)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
diff --git a/vision/nox.py b/vision/noxfile.py
similarity index 79%
rename from vision/nox.py
rename to vision/noxfile.py
index bd9161231f50..fb759b89744e 100644
--- a/vision/nox.py
+++ b/vision/noxfile.py
@@ -25,7 +25,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -52,35 +51,20 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
-
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.6'])
-def system(session, py):
+@nox.session(python=['2.7', '3.6'])
+def system(session):
     """Run the system test suite."""
 
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
         session.skip('Credentials must be set via environment variable.')
 
-    # Run unit tests against all supported versions of Python.
-    session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'sys-' + py
-
     # Use pre-release gRPC for system tests.
     session.install('--pre', 'grpcio')
 
@@ -98,40 +82,33 @@ def system(session, py):
     )
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv dirname.
-    session.virtualenv_dirname = 'setup'
-
     session.install('docutils', 'pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.chdir(os.path.dirname(__file__))
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing')
diff --git a/websecurityscanner/nox.py b/websecurityscanner/noxfile.py
similarity index 81%
rename from websecurityscanner/nox.py
rename to websecurityscanner/noxfile.py
index 5ed90894aa55..69f09e830534 100644
--- a/websecurityscanner/nox.py
+++ b/websecurityscanner/noxfile.py
@@ -24,7 +24,6 @@
 )
 
 
-@nox.session
 def default(session):
     """Default unit test session.
 
@@ -52,55 +51,41 @@ def default(session):
     )
 
 
-@nox.session
-@nox.parametrize('py', ['2.7', '3.5', '3.6', '3.7'])
-def unit(session, py):
+@nox.session(python=['2.7', '3.5', '3.6', '3.7'])
+def unit(session):
     """Run the unit test suite."""
 
-    # Run unit tests against all supported versions of Python.
-    if py != 'default':
-        session.interpreter = 'python{}'.format(py)
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'unit-' + py
-
     default(session)
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.interpreter = 'python3.6'
     session.install('flake8', *LOCAL_DEPS)
     session.install('.')
     session.run('flake8', 'google', 'tests')
 
 
-@nox.session
+@nox.session(python='3.6')
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
-    session.interpreter = 'python3.6'
-
-    # Set the virtualenv directory name.
-    session.virtualenv_dirname = 'setup'
 
     session.install('docutils', 'pygments')
     session.run('python', 'setup.py', 'check', '--restructuredtext',
                 '--strict')
 
 
-@nox.session
+@nox.session(python='3.6')
 def cover(session):
     """Run the final coverage report.
 
     This outputs the coverage report aggregating coverage from the unit
     test runs (not system test runs), and then erases coverage data.
     """
-    session.interpreter = 'python3.6'
     session.install('coverage', 'pytest-cov')
     session.run('coverage', 'report', '--show-missing', '--fail-under=100')
     session.run('coverage', 'erase')