diff --git a/.pylintrc b/.pylintrc
index fee37b3af..becbe3f28 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -69,7 +69,7 @@ confidence=
 # Arranged by category and use symbolic names instead of ids.
 disable=
 # Convention
-    missing-docstring, invalid-name,
+    missing-docstring, invalid-name, bad-continuation,
 # Error
     no-member, no-name-in-module,
 # Information
diff --git a/.travis.yml b/.travis.yml
index 30da3e24e..0b5f11450 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@ sudo: required
 
 language: python
 python:
-  - 2.7
+  - 3.5
 cache: pip
 virtualenv:
   system_site_packages: true
@@ -16,8 +16,8 @@ matrix:
   include:
     - name: Unit tests - Python 2
       env: TOX_ENV=py27
+      python: 2.7
     - name: Unit tests - Python 3
-      python: 3.5
       env: TOX_ENV=py3
     - if: commit_message =~ SECURITY_TEST
       env: TOX_ENV=security
@@ -25,8 +25,9 @@ matrix:
       env: TOX_ENV=lint
     - name: Docs build
       env: TOX_ENV=docs
-    - name: PyGTK unit tests
-      env: TOX_ENV=pygtkui
+      python: 2.7
+    - name: GTK unit tests
+      env: TOX_ENV=gtkui
     - name: Plugins unit tests
       env: TOX_ENV=plugins
 
@@ -46,8 +47,9 @@ addons:
 # Install dependencies
 install:
   - pip install tox tox-venv
-  - "if [ $TOX_ENV == 'pygtkui' ]; then
-    sudo apt install python-gi python-gi-cairo gir1.2-gtk-3.0;
+  - "if [ $TOX_ENV == 'gtkui' ]; then
+    sudo apt install python-gi python-gi-cairo python3-gi python3-gi-cairo \
+    gir1.2-gtk-3.0;
     fi"
   - "if [ $TOX_ENV == 'security' ]; then
     testssl_url=https://github.com/drwetter/testssl.sh/archive/v2.9.5-5.tar.gz;
@@ -59,7 +61,7 @@ before_script:
   - export PYTHONPATH=$PYTHONPATH:$PWD
   - python -c "import libtorrent as lt; print(lt.__version__)"
   # Start xvfb for the GTKUI tests
-  - "if [ $TOX_ENV == 'pygtkui' ]; then
+  - "if [ $TOX_ENV == 'gtkui' ]; then
     /sbin/start-stop-daemon --start --quiet --background \
     --make-pidfile --pidfile /tmp/custom_xvfb_99.pid \
     --exec /usr/bin/Xvfb -- :99 -ac -screen 0 1280x1024x16;
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 30a58504a..d5c61287e 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -96,6 +96,7 @@ autodoc_mock_imports = [
     'libtorrent',
     'psyco',
     'gi',
+    'cairo',
     'curses',
     'win32api',
     'win32file',
diff --git a/packaging/win32/deluge-bbfreeze.py b/packaging/win32/deluge-bbfreeze.py
index 400bf640f..a58161882 100644
--- a/packaging/win32/deluge-bbfreeze.py
+++ b/packaging/win32/deluge-bbfreeze.py
@@ -10,7 +10,7 @@
 # the additional special exception to link portions of this program with the OpenSSL library.
 # See LICENSE for more details.
 #
-
+# isort:skip_file
 from __future__ import print_function
 
 import glob
@@ -19,6 +19,7 @@ import re
 import shutil
 import sys
 
+
 import bbfreeze
 import gtk
 from win32verstamp import stamp
diff --git a/requirements-tests.txt b/requirements-tests.txt
index 841b68fa4..e499bf989 100644
--- a/requirements-tests.txt
+++ b/requirements-tests.txt
@@ -2,6 +2,7 @@ pytest
 pytest-twisted
 pytest-cov
 mock
+pre-commit
 flake8
 flake8-quotes
 flake8-isort
diff --git a/setup.cfg b/setup.cfg
index 4f15bcef5..4651662e3 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -19,10 +19,8 @@ frameworks = CoreFoundation, Foundation, AppKit
 [isort]
 known_standard_library = future_builtins
 known_third_party =
-# Ignore Windows specific modules.
-    bbfreeze, win32verstamp,
 # Ignore gtk modules, primarily for tox testing.
-    pygtk, gtk, gobject, gtk.gdk, pango, cairo, pangocairo, gi
+    cairo, gi,
 # Ignore other module dependencies for pre-commit isort.
     twisted, OpenSSL, pytest, recommonmark, chardet, pkg_resources, zope, mock,
     sphinx
diff --git a/tox.ini b/tox.ini
index 134cde2a6..cb24c5547 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,45 +5,74 @@
 
 [tox]
 envlist = py27, py3, lint, docs
-minversion=2.0
-
-[base]
-deps =
-# Minimum pip version and setuptools to fix issue running on travis.
-    pip>=10
-    setuptools
-    -rrequirements.txt
-
-[testenv]
-install_command = {envpython} -m pip install --ignore-installed {opts} {packages}
-passenv = DISPLAY PYTHONPATH
-setenv = PYTHONPATH = {toxinidir}
-sitepackages = True
-deps =
-    {[base]deps}
-    -rrequirements-tests.txt
-commands =
-    python -c "import libtorrent as lt; print(lt.__version__)"
-    pytest -v -s -m "not (todo or gtkui or security)" deluge/tests
+minversion=3.0
 
 [pytest]
 # Hide logged warnings and errors in test output.
 log_cli_level = CRITICAL
 addopts = -p no:warnings --basetemp=_pytest_temp
 
+# =================
+# Base dependencies
+# =================
+[basesetup]
+# Minimum pip and setuptools versions to fix system and travis issues.
+deps =
+    pip>=10
+    setuptools>=40
+
+[basetests]
+deps =
+    {[basesetup]deps}
+    -rrequirements.txt
+    -rrequirements-tests.txt
+
+[baselint]
+deps =
+    {[basesetup]deps}
+    -rrequirements-tests.txt
+
+[basedev]
+deps =
+    {[basesetup]deps}
+    -rrequirements.txt
+    -rrequirements-dev.txt
+    -rrequirements-tests.txt
+
+[basedocs]
+deps =
+    {[basesetup]deps}
+    -rrequirements-docs.txt
+
+# ======================
+# Test environment setup
+# ======================
+
+[testenv]
+install_command = python -m pip install --ignore-installed {opts} {packages}
+passenv = DISPLAY PYTHONPATH
+setenv =
+    PYTHONPATH = {toxinidir}
+    PYTEST_ADDOPTS = -v -s
+sitepackages = True
+deps = {[basetests]deps}
+commands =
+    python -c "import libtorrent as lt; print(lt.__version__)"
+    pytest -m "not (todo or gtkui or security)" deluge/tests
+
 # ==========
 # Unit tests
 # ==========
 
 [testenv:security]
 setenv = SECURITY_TESTS = True
-commands = pytest -v -s -m "security" deluge/tests/
+commands = pytest -m "security" deluge/tests
 
-[testenv:pygtkui]
-commands = pytest -v -s -m "gtkui" deluge/tests
+[testenv:gtkui]
+commands = pytest -m "gtkui" deluge/tests
 
 [testenv:todo]
-commands = pytest -v -s -m "todo" deluge/tests
+commands = pytest -m "todo" deluge/tests
 
 [testenv:trial]
 setenv = {[testenv]setenv}{:}{toxinidir}/deluge/tests
@@ -55,56 +84,44 @@ commands =
 setenv = PYTHONPATH = {toxinidir}{:}{toxinidir}/deluge/plugins
 commands =
     python setup.py build_plugins --develop --install-dir={toxinidir}/deluge/plugins/
-    pytest -v -s -m "not gtkui" deluge/plugins
+    pytest -m "not gtkui" deluge/plugins
 
 [testenv:pluginsgtkui]
 setenv = PYTHONPATH = {toxinidir}{:}{toxinidir}/deluge/plugins
 commands =
     python setup.py build_plugins --develop --install-dir={toxinidir}/deluge/plugins/
-    pytest -v -s deluge/plugins
+    pytest deluge/plugins
 
-
-# =======================
+# ============
 # Code linting
-# =======================
+# ============
+
+# Disable site-packages to avoid using system installed commands.
 
 [testenv:lint]
+sitepackages = False
 passenv = HOMEPATH SSH_AUTH_SOCK
-deps =
-    pre-commit
-commands =
-    pre-commit run --all-files
+deps = {[baselint]deps}
+commands = pre-commit run --all-files
 
 [testenv:flake8]
-# Disable site packages to avoid using system flake8 which uses
-# hardcoded python path which imports the wrong libraries.
 sitepackages = False
-deps =
-    {[testenv]deps}
-    flake8
-    flake8-quotes
-    flake8-isort
-    pep8-naming
+deps = {[baselint]deps}
 commands =
     flake8 --version
     python -c 'import isort; print(isort.__version__)'
-    flake8
+    flake8 *.py deluge
 
 [testenv:flake8-complexity]
 sitepackages = False
-deps =
-    {[testenv:flake8]deps}
-    mccabe
+deps = {[baselint]deps}
 commands = flake8 --exit-zero --max-complexity 15 deluge
 
-
 [testenv:pylint]
-# Disable site packages to avoid using system installed version
+
 sitepackages = False
 ignore_errors = True
-deps =
-    {[testenv]deps}
-    pylint
+deps = {[baselint]deps}
 commands =
     pylint --version
     pylint deluge
@@ -112,63 +129,40 @@ commands =
     python -m pylint *.py deluge/scripts/*.py
     python -m pylint deluge/plugins/*/deluge/
 
+# ========
+# Coverage
+# ========
 
-# =============
-# Test coverage
-# =============
+[coveragebase]
+commands = coverage run --branch --source=deluge -m pytest -m "not todo" deluge/tests
 
-[testcoveragebase]
-deps =
-    {[testenv]deps}
-    pytest-cov
-    coverage
-commands = coverage run --branch --source=deluge -m pytest -m "not todo" deluge/tests/
-
-[testenv:testcoverage]
-setenv = {[testenv]setenv}
-deps = {[testcoveragebase]deps}
+[testenv:coverage]
 commands =
-    {[testcoveragebase]commands}
-    coverage report
-
-[testenv:testcoverage-html]
-setenv = {[testenv]setenv}
-deps = {[testcoveragebase]deps}
-commands =
-    {[testcoveragebase]commands}
+    {[coveragebase]commands}
     coverage html -d docs/build/htmlcoverage
-
+    coverage report
 
 # ===================
 # Documentation build
 # ===================
 
-# We do not have all dependencies on RTD and travis so we exclude the
-# site packages (sitepackages=False) when building docs so that local
-# tests have a similar environment.
-
-[docsbase]
-sitepackages = False
-changedir = docs
-deps =
-    -rrequirements-docs.txt
-
 [testenv:docs]
 basepython = python2.7
-sitepackages = {[docsbase]sitepackages}
+# Exclude site-packages so local builds have a similar environment to ReadTheDocs.
+sitepackages = False
 skip_install = True
-deps = {[docsbase]deps}
+deps = {[basedocs]deps}
 commands =
     python setup.py clean_docs
     sphinx-build -v -j auto -E -T -b html -d docs/build/doctrees docs/source docs/build/html
 
 [testenv:docscoverage]
 basepython = python2.7
-sitepackages = {[docsbase]sitepackages}
+sitepackages = False
 skip_install = True
-changedir = {[docsbase]changedir}
+changedir = docs
 deps =
-    {[docsbase]deps}
+    {[basedocs]deps}
     pytest-cov
 whitelist_externals = mkdir
 commands =
@@ -176,24 +170,20 @@ commands =
     sphinx-build -W -b coverage -d build/doctrees source build/doccoverage
     pytest --doctest-glob='*.rst'
 
-
 # ========================
 # Development Environment
 # ========================
-[basedev]
-usedevelop = True
-deps = -rrequirements-dev.txt
 
 [testenv:denv2]
 basepython = python2.7
 envdir = .venv2
-usedevelop = {[basedev]usedevelop}
+usedevelop = True
 deps = {[basedev]deps}
 commands =
 
 [testenv:denv3]
 basepython = python3
 envdir = .venv3
-usedevelop = {[basedev]usedevelop}
+usedevelop = True
 deps = {[basedev]deps}
 commands =