- add linting and Python 3.9 test configurations

setup.cfg

@@ -1,6 +1,17 @@
 [bdist_wheel]
 universal = 1
 
+[isort]
+force_single_line = True
+combine_as_imports = True
+line_length = 79
+lines_after_imports = 2
+
+[flake8]
+no-accept-encodings = True
+exclude =
+    bootstrap.py
+
 [coverage:run]
 branch = True
 source = src

tox.ini

@@ -5,13 +5,14 @@ envlist =
     py36,
     py37,
     py38,
+    py39,
     pypy,
     pypy3,
+    lint,
     coverage
 
 [testenv]
 commands =
-    {envbindir}/buildout -c {toxinidir}/buildout.cfg buildout:directory={envdir} buildout:develop={toxinidir} bootstrap
     {envbindir}/buildout -c {toxinidir}/buildout.cfg buildout:directory={envdir} buildout:develop={toxinidir} install test
     coverage run {envbindir}/test {posargs:-cv}
 deps =
@@ -25,6 +26,15 @@ skip_install = true
 basepython = python3.6
 skip_install = true
 deps = coverage
+depends =
+    py27,
+    py35,
+    py36,
+    py37,
+    py38,
+    py39,
+    pypy,
+    pypy3,
 setenv =
     COVERAGE_FILE=.coverage
 commands =
@@ -33,3 +43,33 @@ commands =
     coverage html
     coverage xml
     coverage report
+
+[testenv:lint]
+basepython = python3.6
+skip_install = true
+
+deps =
+    isort
+    flake8
+    # helper to generate HTML reports:
+    flake8-html
+    # Useful flake8 plugins that are Python and Plone specific:
+    flake8-coding
+    flake8-debugger
+    flake8-deprecated
+    flake8-todo
+    mccabe
+    # Potential flake8 plugins that should be used:  # TBD
+    #flake8-blind-except
+    #flake8-commas
+    #flake8-docstrings
+    #flake8-mypy
+    #flake8-pep3101
+    #flake8-plone-hasattr
+    #flake8-string-format
+    #flake8_strict
+    #flake8-quotes
+
+commands =
+    - isort --check-only --diff {toxinidir}/src setup.py
+    flake8 src setup.py