pytest-mpl-oggm

pytest-mpl is a pytest plugin to facilitate image comparison for Matplotlib figures.

OGGM fork

pytest-mpl-oggm` is a shallow fork that adds a few OGGM specific features and enhancements.

Installation:

pip install pytest-mpl-oggm

To run the tests, pass --mpl-oggm to compare the returned figures to the reference images:

pytest --mpl-oggm

For more information about this fork, visit https://github.com/OGGM/pytest-mpl-oggm

Upstream pytest-mpl

For each figure to test, an image is generated and then subtracted from an existing reference image. If the RMS of the residual is larger than a user-specified tolerance, the test will fail. Alternatively, the generated image can be hashed and compared to an expected value.

For more information, see the pytest-mpl documentation.

Usage

First, write test functions that create a figure. These image comparison tests are decorated with @pytest.mark.mpl_image_compare and return the figure for testing:

import matplotlib.pyplot as plt
import pytest

@pytest.mark.mpl_image_compare
def test_plot():
    fig, ax = plt.subplots()
    ax.plot([1, 2])
    return fig

Then, generate reference images by running the test suite with the --mpl-generate-path option:

pytest --mpl-generate-path=baseline

Then, run the test suite as usual, but pass --mpl to compare the returned figures to the reference images:

pytest --mpl

By also passing --mpl-generate-summary=html, a summary of the image comparison results will be generated in HTML format:

For more information on how to configure and use pytest-mpl, see the pytest-mpl documentation.

Contributing

pytest-mpl is a community project maintained for and by its users. There are many ways you can help!

• Report a bug or request a feature on GitHub
• Improve the documentation or code