transform tests compare only first 20 characters

[thet]

The transform tests only compare the first 20 characters. See:

Products.PortalTransforms/Products/PortalTransforms/tests/test_transforms.py

Line 77 in 38ad02e

got_start = got.strip()[:20]

This is not very much. I wanted to add a case to transform a image with a width option referenced in a rest document but wondered why the tests passed without changing the expected output.
When I remove the 20 character restriction many tests fail.

Probably this is done due to avoid flaky tests which fail as soon as a little change in one of the transform tools was made. But this way we cannot test specific features of the transform tools.

[petschki]

@thet this is somewhat harder than I thought ... I'm in progress of fixing python2/3 tests (#34) and tried to compare md5 checksums of input/output files, but they differ horribly ... according to this commit eff68f1 the compared chunk got decreased due to wvware troubles ... but maybe you have a better idea how to compare these files so I can try it in my pull request?