Thanks for the contribution @JelsB. Is it possibe to add a test for this? i.e. I have a PR that will wipe out the old tick decisions, so it'd be nice if this PR includes a test that makes sure I don't do revert your change inadvertently. lib/matplotlib/tests/test_colorbar.py would be the appropriate file. Bonus points if you don't need an image test, but I'm not sure if thats easy in this case. If you do include an image test please try to put into the new style and drop text if its ok for the test:

@image_comparison(baseline_images=['YourImage'], extensions=['png'], style='mpl20', 
       remove_text=True)

EDIT: (ooops, sorry for the spurious close/reopen)

@jklymak I'l make a test in the appropriate file. I don't need an image, I just make a data matrix where a logarithmic scale in useful when plotting. But there seems to be a test already test_colorbar_lognorm_extension(), however without any data to actually show that my fix works. I'll extend that one.

I've added a test case for this fix in lib/matplotlib/tests/test_contour.py instead of lib/matplotlib/tests/test_colorbar.py as it was a kwarg of the function contourf() that wasn't working and not from the colorbar. I've also added the compare image. Everything works for me when I run py.test test_contour.py::test_contourf_log_extension

@JelsB unfortunately this is failing on the image tests. Likely your test images are using an incompatible free type version.

I think you can add to the image comparison method remove_text=True, style=mpl20 (search te code base for the exact syntax) and that should make it so that font errors are not causing the failure. You’ll have to change the test image...

I've changed it. I didn't know it matters, some of the already existing test don't have this either.
Let's see if it passes the tests now.

@JelsB We can't merge tests that don't pass. If you make the test image w/ the incorrect version of FreeType, and they have text in them, they will fail.

Your new images are fine, and passing the tests. However, you still have some style (PEP8) issues. Drill down in the travis-ci python 3.6 test to find them.

This should be squashed before merging to make sure only one of the images makes it into the Repo.

Thanks for your patience with the process!

@jklymak Okay, yes I see the problem. I forgot to check that all of my code has exactly the PEP8 style. I'll fix them. No problem, thanks for guiding me.