https://github.com/gruns/icecream/issues/141

--- icecream-2.1.3.orig/tox.ini
+++ icecream-2.1.3/tox.ini
@@ -0,0 +1,8 @@
+[tox]
+envlist = py27, py35, py36, py37, py38, py39, pypy, pypy3
+
+[testenv]
+deps =
+    nose
+commands =
+    nosetests --exe []