diff --git a/.circleci/config.yml b/.circleci/config.yml
index 0742266..95b0975 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -9,14 +9,11 @@ jobs:
       - checkout
 
       - run: ./demo.py
-
-      # TODO FIXME switch to tox?
-      # - run: pip3 install --user mypy pylint
-      # - run: python3 -m mypy --namespace-packages my
-      # - run: python3 -m pylint -E my
-
       # TODO need to keep full mycfg.py as example? to dummy run CI
 
+      - run: python3 -m pip install --user tox
+      - run: python3 -m tox
+
 
 
 workflows:
diff --git a/setup.py b/setup.py
index 128c96b..ee0402b 100644
--- a/setup.py
+++ b/setup.py
@@ -27,6 +27,12 @@ def main():
         },
 
         python_requires='>=3.5', # depends on the modules though..
+        extras_require={
+            'testing': [
+                'pytest',
+                'pytz',
+            ],
+        },
     )
 
 if __name__ == '__main__':
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..8f9a467
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,30 @@
+[tox]
+minversion = 3.5
+envlist = py36,py37 # ,pylint,mypy
+skip_missing_interpreters = True
+
+# TODO ugh. unclear how to reuse setup.cfg deps in tox
+[testenv]
+passenv = CI CI_* CIRCLE*
+changedir = {toxworkdir}/{envname}
+commands =
+    # pip install -e .[testing]
+    # TODO ??
+    # python -m pytest {posargs}
+    python3 -c 'import my; print(my.__path__)'
+    # TODO run demo.py? just make sure with_my is a bit cleverer?
+    # TODO e.g. under CI, rely on installing
+
+
+# [testenv:mypy]
+# skip_install = true
+# commands =
+#     pip install -e .[testing]
+#     python -m mypy --check-untyped src/cachew
+
+
+# [testenv:pylint]
+# skip_install = true
+# commands =
+#     pip install -e .[testing]
+#     python -m pylint -E src/cachew
diff --git a/with_my.example b/with_my.example
index c363bf2..9a0824e 100755
--- a/with_my.example
+++ b/with_my.example
@@ -41,7 +41,7 @@ if __name__ == '__main__':
 
     # TODO wonder why py.typed file in mycfg didn't help?
     for v in ['MYPYPATH', 'PYTHONPATH']:
-        upd(v, MY_DIR)
+        upd(v, MY_DIR) # TODO not sure if it should do it if you use install -e?
         upd(v, MYCFG_DIR)
 
     rest = sys.argv[1:]