Helllo, I’m seeing a strange issue when running unittests on python3.3 and python3.4 that somehow involves matplotlib. My code has a somewhat complicated setup, but I think I’ve boiled the issue down to the following reproduction steps
import unittest
import warnings
import matplotlib.pyplot
class TestMe(unittest.TestCase):
def test_warn(self):
with self.assertWarns(UserWarning):
warnings.warn("a warning", UserWarning)
if name == “main”:
unittest.main()
It looks like it should pass, but it errors as follows
E
···
======================================================================
ERROR: test_warn (main.TestMe)
Traceback (most recent call last):
File “/homes/5/jevans/Downloads/testit.py”, line 8, in test_warn
with self.assertWarns(UserWarning):
File “/space/getafix/1/users/jevans/anaconda/envs/py3k/lib/python3.3/unittest/case.py”, line 177, in enter
for v in sys.modules.values():
RuntimeError: dictionary changed size during iteration
Ran 1 test in 0.002
If the matplotlib import is changed to just
import matlotlib
or if the matplotlib import is commented out altogether, it then passes. I’m seeing the behavior on Anaconda with python 3.3 and matplotlib 1.3.1 on both mac and linux, but also with MacPorts with pythons 3.3 and 3.4, matplotlib 1.3.1. All seems fine with a Fedora 20 laptop with python 3.3 and also matplotlib 1.3.1.
–
John Evans