PR Summary

Fixes #10582

import matplotlib.pyplot as plt
import numpy as np

gx = np.linspace(-5, 5, 10)
img = np.hypot(gx, gx[:, None])

fig = plt.figure()
ax = fig.add_axes([0, 0, 1, 1])
mesh = ax.pcolormesh(gx, gx, img)
plt.colorbar(mesh)

plt.show()

failed with an attribute error. This is the most straightforward way of checking for that.

Not sure if this should have a test or not. Seems that maybe pyplot-created colorbars are not tested if this one got through the test suite...

PR Checklist

• Has Pytest style unit tests
• Code is PEP 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way