Add unit tests for participants_file and append_list_as_row

[sangfrois]

Adresses #252 by testing new functions in bids.py and utils.py

Proposed Changes

• testing append_list_as_row()
• testing participants_file()

This would lead to increased coverage 👍

[sangfrois]

I'm assigning Eneko to review this PR as we discussed.

No pressure. I still have to add the tests for the participants file.

[codecov]

Codecov Report

Merging #254 into master will increase coverage by 0.98%.
The diff coverage is 93.33%.

@@            Coverage Diff             @@
##           master     #254      +/-   ##
==========================================
+ Coverage   93.39%   94.38%   +0.98%     
==========================================
  Files           9        9              
  Lines         772      783      +11     
==========================================
+ Hits          721      739      +18     
+ Misses         51       44       -7     

Impacted Files	Coverage Δ
phys2bids/phys2bids.py	90.97% <93.33%> (+0.81%)	⬆️
phys2bids/bids.py	96.11% <0.00%> (+6.79%)	⬆️

[sangfrois]

Both new functions should be checked and up to date with master. I'm not sure about the last tests in test_bids.py - Waiting for feedback.

[eurunuela]

@sangfrois I added the remaining test. It was just a matter of repeating the last one you wrote to check that the subject was already in the file.

I don't know why Travis is complaining about numpy today. It probably has something to do with the lowest numpy version we support. Anyway, the test pass and coverage increases significantly, so good job! 🙌🏻

Let's see if we fix the issue in Travis and then we review and merge this.

[vinferrer]

LGTM, nice unit tests