RFC: Display differences

[wiredfool]

I've been thinking about something like this since we had the issue that was non-reproducable on any of my machines.

What this does is push all test failures for assert_image_equal and assert_image_similar to a webservice, where it displays those images and the difference.

======================================================================

FAIL: TestUploader.test_upload_equal

----------------------------------------------------------------------

Traceback (most recent call last):

  File "/home/travis/build/wiredfool/Pillow/Tests/test_uploader.py", line 10, in test_upload_equal

    self.assert_image_equal(result, target)

  File "/home/travis/build/wiredfool/Pillow/Tests/helper.py", line 104, in assert_image_equal

    self.fail(msg or "got different content")

AssertionError: got different content

-------------------- >> begin captured logging << --------------------

urllib3.connectionpool: DEBUG: Starting new HTTPS connection (1): fmuvehxed0.execute-api.us-east-2.amazonaws.com

urllib3.connectionpool: DEBUG: https://fmuvehxed0.execute-api.us-east-2.amazonaws.com:443 "GET /prod/upload HTTP/1.1" 200 3421

urllib3.connectionpool: DEBUG: Starting new HTTPS connection (1): s3.us-east-2.amazonaws.com

urllib3.connectionpool: DEBUG: https://s3.us-east-2.amazonaws.com:443 "POST /pillow-test-image-results HTTP/1.1" 204 0

urllib3.connectionpool: DEBUG: Starting new HTTPS connection (1): s3.us-east-2.amazonaws.com

urllib3.connectionpool: DEBUG: https://s3.us-east-2.amazonaws.com:443 "POST /pillow-test-image-results HTTP/1.1" 204 0

helper: ERROR: Url for test images: https://fmuvehxed0.execute-api.us-east-2.amazonaws.com/prod/show/1510948233.21/

--------------------- >> end captured logging << ---------------------

I'm not 100% on the output yet, and we're still not going to trigger on some forms of errors.

Comments?

[hugovk]

Sounds like a good idea.