add tox configuration, and expose test runner via that

.gitignore

@@ -19,6 +19,7 @@ dmypy.json
 # Packages
 *.egg
 *.egg-info
+*.eggs
 
 # IDEs
 .idea

runtests.py

@@ -83,7 +83,7 @@ def add_pytest(self, files: List[Tuple[str, str]], coverage: bool = True) -> Non
         if not pytest_files:
             return
         pytest_args = pytest_files + self.arglist + self.pyt_arglist
-        always_append = ['-n', 'auto', '--cov-append', ' --cov-report=']
+        always_append = ['-n', 'auto', '--cov-append', '--cov-report=']
         if coverage and self.coverage:
             args = [sys.executable, '-m', 'pytest', '--cov=mypy'] + always_append + pytest_args
         else:

setup.cfg

@@ -25,7 +25,8 @@ exclude =
   typeshed/*,
   # during runtests.py flake8 might be started when there's still examples in the temp dir
   tmp-test-dirs/*
-
+  .tox
+  .eggs
 
 # Things to ignore:
 #   E251: spaces around default arg value (against our style)

tox.ini

@@ -0,0 +1,40 @@
+[tox]
+minversion = 2.9.1
+skip_missing_interpreters = true
+envlist = py34,
+          py35,
+          py36,
+          py37,
+          lint,
+          type,
+          docs
+
+[testenv]
+description = run the test driver with {basepython}
+deps = -r ./test-requirements.txt
+commands = python runtests.py -x lint -x package {posargs}
+
+[testenv:lint]
+description = check the code style
+basepython = python3.6
+commands = python runtests.py lint {posargs}
+
+[testenv:type]
+description = type check ourselves
+basepython = python3.6
+commands = python runtests.py testselfcheck -p '-n0' -p '-v'
+
+[testenv:docs]
+description = invoke sphinx-build to build the HTML docs
+basepython = python3.6
+deps = -r docs/requirements-docs.txt
+commands = sphinx-build -d "{toxworkdir}/docs_doctree" docs/source "{toxworkdir}/docs_out" --color -W -bhtml {posargs}
+
+[testenv:dev]
+description = generate a DEV environment, that has all project libraries
+usedevelop = True
+basepython = python3.6
+deps = -r ./test-requirements.txt
+       -r docs/requirements-docs.txt
+commands = python -m pip list --format=columns
+           python -c 'import sys; print(sys.executable)'