Add tox config

pyproject.toml

@@ -98,3 +98,57 @@ autodoc_exclude_members = [
     "__abstractmethods__",
     "__hash__",
 ]
+[tool.tox]
+[tox]
+description = list of environments against which tox runs the tests
+envlist =
+    reformat
+    check
+    py3-fast
+# See https://tox.readthedocs.io/en/latest/example/package.html#flit
+isolated_build = True
+isolated_build_env = build
+skip_missing_interpreters = False
+
+[gh-actions]
+python =
+    3.7: py37
+    3.8: py38
+    3.9: py39
+    3.10: py310, mypy
+
+[testenv]
+# install pytest in the virtualenv where commands will be executed
+setenv =
+    PYTHONUNBUFFERED = yes
+    PIP_PREFER_BINARY = 1
+passenv = *
+extras =
+  dev
+# This is already the default, but we include it here
+# to remind ourselves that usedevelop is incompatible with flit,
+# see https://tox.readthedocs.io/en/latest/config.html#conf-usedevelop
+usedevelop = False
+commands =
+    pytest {env:PYTEST_MARKERS:} {env:PYTEST_EXTRA_ARGS:} {posargs:-vv}
+
+[testenv:check]
+description = this environments checks for flake8 and black
+deps =
+    black==21.6b0
+    pyproject-flake8
+    flake8
+    build
+skip_install = true
+commands =
+    pflake8 src tests apps
+    black --check --diff src tests apps
+    python -m build
+
+[testenv:reformat]
+description = reformats the code using black
+deps =
+    black==21.6b0
+skip_install = true
+commands =
+    black src tests apps