diff --git a/nfv/nfv-debug-tools/histogram_analysis/plotter.py b/nfv/nfv-debug-tools/histogram_analysis/plotter.py
index dd6088af..223b94ae 100755
--- a/nfv/nfv-debug-tools/histogram_analysis/plotter.py
+++ b/nfv/nfv-debug-tools/histogram_analysis/plotter.py
@@ -348,7 +348,7 @@ def setFilename(graphName):
         os.makedirs("Graphs/")
     os.chdir(os.path.join(dir, 'Graphs/'))
     if not graphName:
-            graphName = time.strftime("%m-%d-%Y")
+        graphName = time.strftime("%m-%d-%Y")
     if os.path.exists(str(graphName + ".html")):
         n = 1
         while(not validName):
diff --git a/nfv/nfv-tests/nfv_unit_tests/tests/test_database_upgrades.py b/nfv/nfv-tests/nfv_unit_tests/tests/test_database_upgrades.py
index 5098ec53..876c9111 100755
--- a/nfv/nfv-tests/nfv_unit_tests/tests/test_database_upgrades.py
+++ b/nfv/nfv-tests/nfv_unit_tests/tests/test_database_upgrades.py
@@ -4,7 +4,9 @@
 # SPDX-License-Identifier: Apache-2.0
 #
 import os
+import shutil
 import subprocess
+import tempfile
 
 from nfv_vim import database
 from nfv_vim import tables
@@ -14,24 +16,34 @@ from . import testcase  # noqa: H304
 
 class TestNFVDatabaseUpgrade(testcase.NFVTestCase):
 
+    def setUp(self):
+        super(TestNFVDatabaseUpgrade, self).setUp()
+        root_dir = os.environ['VIRTUAL_ENV']
+        # create a directory to hold the DB, randomly named, under the tox env
+        self.db_dir = tempfile.mkdtemp(dir=root_dir)
+
+    def tearDown(self):
+        super(TestNFVDatabaseUpgrade, self).tearDown()
+        shutil.rmtree(self.db_dir)
+
     def test_nfv_vim_database_upgrade_from_19_12(self):
         """
         Test VIM database upgrades from stx 19_12
         """
         root_dir = os.environ['VIRTUAL_ENV']
-
+        # stage some old data
         devnull = open(os.devnull, 'w')
         try:
             vim_cmd = ("nfv-vim-manage db-load-data -d %s "
-                       "-f %s/nfv_vim_db_stx_19.12" % (root_dir, root_dir))
+                       "-f %s/nfv_vim_db_stx_19.12" % (self.db_dir, root_dir))
 
             subprocess.check_call([vim_cmd], shell=True, stderr=devnull)
-
         except subprocess.CalledProcessError:
             raise
 
+        # migrate the old data
         config = dict()
-        config['database_dir'] = root_dir
+        config['database_dir'] = self.db_dir
         database.database_initialize(config)
         database.database_migrate_data()
         tables.tables_initialize()
diff --git a/nfv/nfv-vim/nfv_vim/api/openstack/_objects.py b/nfv/nfv-vim/nfv_vim/api/openstack/_objects.py
index aed49c86..5e94298c 100755
--- a/nfv/nfv-vim/nfv_vim/api/openstack/_objects.py
+++ b/nfv/nfv-vim/nfv_vim/api/openstack/_objects.py
@@ -60,6 +60,7 @@ class OpenStackServices(Constants):
     HEAT = Constant('heat')
     FM = Constant('fm')
 
+
 # OpenStack Services Constant
 OPENSTACK_SERVICE = OpenStackServices()
 
diff --git a/nfv/nfv-vim/nfv_vim/network_rebalance/_dhcp_rebalance.py b/nfv/nfv-vim/nfv_vim/network_rebalance/_dhcp_rebalance.py
index 6de901a8..046e969e 100644
--- a/nfv/nfv-vim/nfv_vim/network_rebalance/_dhcp_rebalance.py
+++ b/nfv/nfv-vim/nfv_vim/network_rebalance/_dhcp_rebalance.py
@@ -27,6 +27,7 @@ class AgentType(Constants):
     L3 = Constant('L3 agent')
     DHCP = Constant('DHCP agent')
 
+
 AGENT_TYPE = AgentType()
 
 
@@ -43,6 +44,7 @@ class DHCPRebalanceState(Constants):
     HOLD_OFF = Constant('HOLD_OFF')
     DONE = Constant('DONE')
 
+
 DHCP_REBALANCE_STATE = DHCPRebalanceState()
 
 
diff --git a/nfv/nfv-vim/nfv_vim/network_rebalance/_network_rebalance.py b/nfv/nfv-vim/nfv_vim/network_rebalance/_network_rebalance.py
index 06258e7f..13506db8 100644
--- a/nfv/nfv-vim/nfv_vim/network_rebalance/_network_rebalance.py
+++ b/nfv/nfv-vim/nfv_vim/network_rebalance/_network_rebalance.py
@@ -27,6 +27,7 @@ class AgentType(Constants):
     L3 = Constant('L3 agent')
     DHCP = Constant('DHCP agent')
 
+
 AGENT_TYPE = AgentType()
 
 
@@ -46,6 +47,7 @@ class L3RebalanceState(Constants):
     HOLD_OFF = Constant('HOLD_OFF')
     DONE = Constant('DONE')
 
+
 L3_REBALANCE_STATE = L3RebalanceState()
 
 
diff --git a/nfv/nfv-vim/nfv_vim/strategy/_strategy_defs.py b/nfv/nfv-vim/nfv_vim/strategy/_strategy_defs.py
index ad258b1d..b137a304 100755
--- a/nfv/nfv-vim/nfv_vim/strategy/_strategy_defs.py
+++ b/nfv/nfv-vim/nfv_vim/strategy/_strategy_defs.py
@@ -54,4 +54,5 @@ class FirmwareUpdateLabels(object):
     DEVICE_IMAGE_UPDATE_FAILED = Constant('failed')
     DEVICE_IMAGE_UPDATE_IN_PROGRESS_ABORTED = Constant('in-progress-aborted')
 
+
 FW_UPDATE_LABEL = FirmwareUpdateLabels()
diff --git a/nfv/test-requirements.txt b/nfv/test-requirements.txt
index c3ed418b..06cc8f76 100644
--- a/nfv/test-requirements.txt
+++ b/nfv/test-requirements.txt
@@ -1 +1,13 @@
-hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
+# The order of packages is significant, because pip processes them in the order
+# of appearance. Changing the order has an impact on the overall integration
+# process, which may cause wedges in the gate later.
+hacking>=1.1.0,<=2.0.0 # Apache-2.0
+astroid<2.0;python_version<"3.0" # GPLv2
+astroid<= 2.2.5;python_version>="3.0" # GPLv2
+bandit<1.6.0;python_version>="3.0"
+coverage>=3.6
+fixtures>=3.0.0 # Apache-2.0/BSD
+mock>=2.0.0 # BSD
+pylint<2.1.0;python_version<"3.0" # GPLv2
+pylint<2.4.0;python_version>="3.0" # GPLv2
+testtools>=2.2.0 # MIT
diff --git a/nfv/tox.ini b/nfv/tox.ini
index 84652c09..2812d90c 100644
--- a/nfv/tox.ini
+++ b/nfv/tox.ini
@@ -15,12 +15,14 @@ skipsdist = True
 stxdir = {toxinidir}/../..
 
 [testenv]
-recreate = True
 install_command = pip install \
     -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/stable/stein/upper-constraints.txt} \
     {opts} {packages}
 whitelist_externals = cp
 
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
+
 [nfv]
 nfv_base_dir = .
 nfv_client_dir = ./nfv-client
@@ -57,30 +59,35 @@ deps = {[nfv]nfv_client_dir}
 verbosity=2
 
 [flake8]
-# Temporarily ignoring these warnings
-# E121 continuation line under-indented for hanging indent
-# E122 continuation line missing indentation or outdented
-# E123 closing bracket does not match indentation of opening bracket
-# E124 closing bracket does not match visual indentation
-# E126 continuation line over-indented for hanging indent
-# E127 continuation line over-indented for visual indent
-# E128 continuation line under-indented for visual indent
-# E129 visually indented line with same indent as next logical line
-# E501 line too long
 # - hacking codes -
 # H104: File contains nothing but comments
 # H404: multi line docstring should start without a leading new line
 # H405: multi line docstring summary not separated with an empty line
 # H501: Do not use self.__dict__ for string formatting
-# - flake8 codes -
-# F823 local variable referenced before assignment
+# warnings
+# W503 line break before binary operator
+# W504  line break after binary operator
+# W605 invalid escape sequence
+# errors
+# E121 continuation line under-indented for hanging indent
+# E122 continuation line missing indentation or outdented
+# E124 closing bracket does not match visual indentation
+# E126 continuation line over-indented for hanging indent
+# E127 continuation line over-indented for visual indent
+# E128 continuation line under-indented for visual indent
+# E129 visually indented line with same indent as next logical line
+# flake8
 # F841 local variable 'e' is assigned to but never used
-ignore = E121,E122,E123,E124,E126,E127,E128,E129,E501,H104,H404,H405,H501,F823,F841
+ignore = H104,H404,H405,H501,
+         W503,W504,W605,
+         E121,E122,E124,E126,E127,E128,E129,
+         F841
 # H106 Don’t put vim configuration in source files (off by default).
 # H203 Use assertIs(Not)None to check for None (off by default).
 # TODO: enable: H904 Delay string interpolations at logging calls (off by default).
 enable-extensions = H106,H203
-max-line-length = 84
+# rather than suppress E501 line too long, set max line length and reduce later
+max-line-length = 185
 
 [testenv:pep8]
 basepython = python3
@@ -94,12 +101,9 @@ commands =
 [testenv:pylint]
 basepython = python2.7
 deps = {[nfv]deps}
+       -r{toxinidir}/test-requirements.txt
        {[nfv]nfv_test_dir}/nfv_scenario_tests
-       fixtures
        jinja2
-       mock
-       testtools
-       pylint
 commands = pylint {[nfv]nfv_client_src_dir}  \
                   {[nfv]nfv_common_src_dir}  \
                   {[nfv]nfv_plugins_src_dir} \
@@ -120,8 +124,8 @@ exclude = ./nfv-docs,./nfv-tests,./nfv-debug-tools,unit_test
 
 [testenv:bandit]
 deps = {[nfv]deps}
-       bandit
-basepython = python2.7
+       -r{toxinidir}/test-requirements.txt
+basepython = python3
 commands = bandit --ini tox.ini -f txt -r {[nfv]nfv_base_dir}
 
 [testenv:py27]
diff --git a/nova-api-proxy/test-requirements.txt b/nova-api-proxy/test-requirements.txt
new file mode 100644
index 00000000..2e3f81d3
--- /dev/null
+++ b/nova-api-proxy/test-requirements.txt
@@ -0,0 +1,12 @@
+# The order of packages is significant, because pip processes them in the order
+# of appearance. Changing the order has an impact on the overall integration
+# process, which may cause wedges in the gate later.
+hacking>=1.1.0,<=2.0.0 # Apache-2.0
+astroid<2.0;python_version<"3.0" # GPLv2
+astroid<= 2.2.5;python_version>="3.0" # GPLv2
+bandit<1.6.0;python_version>="3.0"
+coverage>=3.6
+fixtures>=3.0.0 # Apache-2.0/BSD
+mock>=2.0.0 # BSD
+pylint<2.1.0;python_version<"3.0" # GPLv2
+pylint<2.4.0;python_version>="3.0" # GPLv2
diff --git a/nova-api-proxy/tox.ini b/nova-api-proxy/tox.ini
index e4073772..f06f1bc2 100644
--- a/nova-api-proxy/tox.ini
+++ b/nova-api-proxy/tox.ini
@@ -5,6 +5,7 @@ skipsdist = True
 
 [testenv]
 basepython = python3
+sitepackages = False
 install_command = pip install \
     -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/stable/stein/upper-constraints.txt} \
     {opts} {packages}
@@ -16,6 +17,8 @@ setenv = VIRTUAL_ENV={envdir}
 commands = find {toxinidir} -type f -not -path '{toxinidir}/.tox/*' -not -path '*/__pycache__/*' -name '*.py[c|o]' -delete
 whitelist_externals = find
 
+deps=-r{toxinidir}/test-requirements.txt
+
 [testenv:venv]
 commands = {posargs}
 
@@ -36,15 +39,13 @@ max-line-length=84
 [testenv:pep8]
 usedevelop = False
 skip_install = True
-deps =
-    hacking
-    flake8-bugbear
 commands =
     flake8
 
 [testenv:pylint]
 basepython = python2.7
-deps =
+deps=
+    -r{toxinidir}/test-requirements.txt
     eventlet
     oslo.config
     oslo.log
@@ -52,6 +53,5 @@ deps =
     PasteDeploy
     routes
     webob
-    pylint
 commands = pylint nova-api-proxy/nova_api_proxy --rcfile=pylint.rc
 
diff --git a/test-requirements.txt b/test-requirements.txt
index 67d9ddf1..0fbded31 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,6 +1,4 @@
 bashate < 1.0.0
 PyYAML >= 3.1.0
-yamllint >= 0.5.2
-# The following are for py27 and py35
-mock  # BSD
-nose  # LGPL
+yamllint<1.26.1;python_version>="3.0" # GPLv2
+
diff --git a/tox.ini b/tox.ini
index 150ac999..e5e39b5e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,7 +27,7 @@ basepython = python3
 description = Dummy environment to allow pep8 to be run in subdir tox
 
 [testenv:pylint]
-basepython = python3
+basepython = python2.7
 description = Dummy environment to allow pylint to be run in subdir tox
 
 [testenv:linters]