obspy.core.util.testing.ImageComparison

class ImageComparison(image_path, image_name, reltol=1, adjust_tolerance=True, *args, **kwargs)[source]

Bases: obspy.core.util.base.NamedTemporaryFile

Handles the comparison against a baseline image in an image test.

Note

Baseline images are created using matplotlib version 1.3.1.

Parameters:
  • image_path (str) Path to directory where the baseline image is located
  • image_name (str) Filename (with suffix, without directory path) of the baseline image
  • reltol (float, optional) Multiplier that is applied to the default tolerance value (i.e. 10 means a 10 times harder to pass test tolerance).
  • adjust_tolerance (bool, optional) Adjust the tolerance based on the matplotlib version. Can optionally be turned off to simply compare two images.

The class should be used with Python’s “with” statement. When setting up, the matplotlib rcdefaults are set to ensure consistent image testing. After the plotting is completed, the ImageComparison.compare() method is called automatically at the end of the “with” block, comparing against the previously specified baseline image. This raises an exception (if the test fails) with the message string from matplotlib.testing.compare.compare_images(). Afterwards all temporary files are deleted automatically.

Note

If images created during the testrun should be kept after the test, set environment variable OBSPY_KEEP_IMAGES to any value before executing the test (e.g. with $ OBSPY_KEEP_IMAGES= obspy-runtests or $ OBSPY_KEEP_IMAGES= python test_sometest.py). For obspy-runtests the option “keep-images” can also be used instead of setting an environment variable. Created images and diffs for failing tests are then stored in a subfolder “testrun” under the baseline image’s directory. To only keep failed images and the corresponding diff image, additionally set environment variable OBSPY_KEEP_ONLY_FAILED_IMAGES to any value before executing the test.

Example

>>> from obspy import read
>>> with ImageComparison("/my/baseline/folder", 'plot.png') as ic:
...     st = read()  
...     st.plot(outfile=ic.name)  
...     # image is compared against baseline image automatically

Attributes

__abstractmethods__ frozenset() -> empty frozenset object
__doc__ unicode(string [, encoding[, errors]]) -> object
__module__ str(object) -> string
closed

Public Methods

compare Run a custom version
read
seek
tell
write

Private Methods

_copy_tempfiles Copies created images from tempfiles to a subfolder of baseline images.
_get_final_filenames Helper function returning the
_upload_images Uploads images to imgur.

Special Methods

__enter__ Set matplotlib defaults.
__exit__ Remove tempfiles and store created images if OBSPY_KEEP_IMAGES
__init__