Commit 596d5c5c authored by Jérome Perrin's avatar Jérome Perrin

testing/utils: ImageComparisonTestCase

This was in plantuml test, but can be used in other cases where we want
to snapshot test screenshots or images produced by softwares.

See merge request !203
parents a9739e29 ad43e272
......@@ -28,8 +28,16 @@
import socket
import hashlib
import unittest
from contextlib import closing
try:
import typing
if typing.TYPE_CHECKING:
from PIL import Image # pylint:disable=unused-import
except ImportError:
pass
# Utility functions
def findFreeTCPPort(ip=''):
......@@ -50,3 +58,29 @@ def getPortFromPath(path):
return 1024 + int(
hashlib.md5(path.encode('utf-8', 'backslashreplace')).hexdigest(),
16) % (65535 - 1024)
class ImageComparisonTestCase(unittest.TestCase):
"""TestCase with utility method to compare images.
The images must be passed as instances of `PIL.Image`
"""
def assertImagesSimilar(self, i1, i2, tolerance=5):
# type: (Image, Image, float) -> None
"""Assert images difference between images is less than `tolerance` %.
taken from https://rosettacode.org/wiki/Percentage_difference_between_images
"""
pairs = zip(i1.getdata(), i2.getdata())
if len(i1.getbands()) == 1:
# for gray-scale jpegs
dif = sum(abs(p1 - p2) for p1, p2 in pairs)
else:
dif = sum(abs(c1 - c2) for p1, p2 in pairs for c1, c2 in zip(p1, p2))
ncomponents = i1.size[0] * i1.size[1] * 3
self.assertLessEqual((dif / 255.0 * 100) / ncomponents, tolerance)
def assertImagesSame(self, i1, i2):
# type: (Image, Image) -> None
"""Assert images are exactly same."""
self.assertImagesSimilar(i1, i2, 0)
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