test_selection_no_warning fails under unittest

[mdickinson]

When running the test suite against an installed Chaco with python -m unittest discover -v chaco (from a directory far away from the GitHub checkout), I see one test failure:

======================================================================
FAIL: test_selection_no_warning (chaco.tools.tests.test_range_selection.RangeSelectionTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/mdickinson/Desktop/chacotest/lib/python3.7/site-packages/chaco/tools/tests/test_range_selection.py", line 70, in test_selection_no_warning
    self.assertEqual(w, [])
AssertionError: Lists differ: [<warnings.WarningMessage object at 0x11eea8f90>] != []

First list contains 1 additional elements.
First extra element 0:
<warnings.WarningMessage object at 0x11eea8f90>

- [<warnings.WarningMessage object at 0x11eea8f90>]
+ []

The test passes under nose.

Seen under both Python 3.6 and Python 3.7 on macOS 10.14.5 with Chaco installed from the soon-to-be 4.8.0 commit (4437360).

[jvkersch]

@mdickinson I can't immediately reproduce on Linux; would you mind listing what you have in your environment?

[mdickinson]

Here are the installed packages:

(chacotest) mirzakhani:Desktop mdickinson$ pip freeze
chaco===4.7.1.dev172.dev172.dev172
Cython==0.29.12
enable==4.8.0
fonttools==3.43.2
mock==3.0.5
numpy==1.16.4
Pillow==6.1.0
pyface==6.1.1
six==1.12.0
traits==5.1.2
traitsui==6.1.1

And here's the exact sequence of steps I used:

• check out current Chaco master (commit 785f180)
• create an sdist with python setup.py sdist
• copy that sdist to my Desktop cp dist/chaco-4.7.1.dev172.tar.gz ~/Desktop/, and make the Desktop my current working directory
• create a new Python 3.7.4 venv and activate it: python -m venv chacotest, source chacotest/bin/activate
• pip install mock numpy Cython
• pip install chaco-4.7.1.dev172.tar.gz
• Run tests with python -m unittest discover -v chaco

[mdickinson]

Digging into the failure, the warning message is:

(Pdb) p w[0].message
DeprecationWarning('elementwise comparison failed; this will raise an error in the future.')