MDAnalysis 1.0.0 tests fail with "TypeError: use() got an unexpected keyword argument 'warn'"

[orbeckst]

Note: This problem (#2191 (comment)) was already fixed (in PR #2763) and will not affect upcoming 1.0.1. This issue was raised so that current users of 1.0.0 have an easy way to find this problem that currently affects them. This issue will be closed when 1.0.1 is releases #2768 .

Expected behavior

Conda installed MDA "just works".

Actual behavior

Following our installation instructions, MDAnalysis tests fail with

miniconda3/envs/mdaenv/lib/python3.6/site-packages/MDAnalysisTests/__init__.py:126: in <module>
    matplotlib.use('agg', warn=False)
E   TypeError: use() got an unexpected keyword argument 'warn'

A new version of matplotlib (3.3.1 in my case) is installed that removed the warn kwarg.

Code to reproduce the behavior

conda config --add channels conda-forge
conda update --yes conda
conda create --yes -n mdaenv python=3.6
conda install --yes -n mdaenv MDAnalysis MDAnalysisTests
source activate mdaenv
pytest --disable-pytest-warnings --pyargs MDAnalysisTests

Workaround

Downgrade mpl

conda install 'matplotlib<3.3'

Current version of MDAnalysis

• Which version are you using? (run python -c "import MDAnalysis as mda; print(mda.__version__)") 1.0.0
• Which version of Python (python -V)? any
• Which operating system? any

[IAlibay]

This should have been addressed in 1.0.1 (I'm running matplotlib-base 3.3.4 without any issues).