Restore tox file

Author: Faustasm

tox.ini

@@ -0,0 +1,42 @@
+# Tox (https://tox.readthedocs.io/) is a tool for running tests
+# in multiple virtualenvs. This configuration file will run the
+# test suite on all supported python versions. To use it, "pip install tox"
+# and then run "tox" from this directory.
+
+[tox]
+envlist = py27, py36, py37, py38, py39, pypy3
+skip_missing_interpreters = True
+
+[testenv]
+commands = py.test test/
+deps = -rrequirements.txt
+       -rrequirements-dev.txt
+
+[testenv:integration]
+passenv = *
+commands = py.test test/ {posargs: -x}
+deps = -rrequirements.txt
+       -rrequirements-dev.txt
+
+[flake8]
+ignore = D100,  # missing docstring in public module
+         D105,
+         D200,  # one line docstring should fit on one line with quotes
+         D203,  # 1 blank line required before class docstring
+         D205,  # blank line required after description (in docstrings)
+         H101,
+         H238,
+         H301,
+         H304,
+         H404,
+         H405
+exclude =
+    # No need to traverse our git directory
+    .git,
+    # There's no value in checking cache directories
+    __pycache__,
+    # ...or build ones
+    build,
+    # Ignore virtualenv
+    ENV
+max-line-length = 99