Add a test for public link download

[nickvergessen]

A simple test that covers https://github.com/owncloud/core/pull/19619

@PVince81 @DeepDiver1975

Before the fix (commit https://github.com/owncloud/core/commit/cd818e7419fb39d97683ecc5803534b0ed632596):

$ ./bin/smash lib/oc-tests/test_shareLink.py
[ ... cut ... ]
ERROR - publicDownloader - md5 of modified file /home/nickv/ownCloud/Smashbox/ramdir/test_shareLink-151007-154327/publicDownloader/TEST_FILE_LINK_SHARE.dat changed and should not have: expected 45b565af28a2998fa8d5dae7eb6e660e, got eb964678f7e0a61e833ae2e45e7d2119 "md5 of modified file %s changed and should not have: expected %s, got %s" % (fn, md5, actual_md5)) failed in expect_not_modified() ["/home/nickv/ownCloud/Smashbox/smashbox/python/smashbox/utilities/__init__.py" at line 692]
ERROR - publicDownloader - 1 error(s) reported

After the fix (commit https://github.com/owncloud/core/commit/f5c390fffd19971b97e54f0c32073523b38c6140):

Test passes :white_check_mark:

[PVince81]

Nice :+1:

[nickvergessen]

Will try to cover full folder download and "some files" download as well

[DeepDiver1975]

Will try to cover full folder download and "some files" download as well

NICE!

[nickvergessen]

Done

Covers:

• Single file share
• Folder share, single file direct download (click on file list)
• Folder share, select single file and download (checkbox)
• Folder share, select multiple files and download (checkbox) - broken on 32bits: https://github.com/owncloud/core/issues/19640
• Folder share, download full folder - broken on 32bits: https://github.com/owncloud/core/issues/19640

[PVince81]

:+1: