Setup

matplotlib.__version__ = 1.5.1
matplotlib.__version__numpy__ = 1.6
Python 3.5.1, IPython 4.1.2 running under anaconda
OS: Red Hat 6.5

Matplotlib installed with conda install matplotlib.

Issue

Supplying invalid drawstyle parameter to plot (and possible others) does not raise an error. I would expect the following not to work, but it does:

>>> import matplotlib.pyplot as plt
>>> plt.plot(range(5), range(5), drawstyle='mwahahahahaha')

For contrast, trying the same thing with fillstyle raises the expected error:

>>> plt.plot(range(5), range(5), fillstyle='mwahahahahaha')
...
ValueError: Unrecognized fillstyle full left right bottom top none

Notes

The issue seems to be happening here:

drawstyles = ('default', 'steps', 'steps-pre', 'steps-mid', 'steps-post')
if drawstyle not in drawstyles:
    raise ValueError(' '.join(('Unrecognized drawstyle',) + drawstyles))

would mess up something or another. If not, I would be glad to make the change.

To help us understand and resolve your issue please check that you have provided
the information below.