Unable to test extractor

[gslvrp]

Checklist

• I'm reporting a broken site support issue
• I've verified that I'm running youtube-dl version 2019.11.28
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar bug reports including closed ones
• I've read bugs section in FAQ

Verbose log

Traceback (most recent call last):
  File "test/test_download.py", line 265, in <module>
    unittest.main()
  File "/usr/lib/python2.7/unittest/main.py", line 94, in __init__
    self.parseArgs(argv)
  File "/usr/lib/python2.7/unittest/main.py", line 149, in parseArgs
    self.createTests()
  File "/usr/lib/python2.7/unittest/main.py", line 158, in createTests
    self.module)
  File "/usr/lib/python2.7/unittest/loader.py", line 130, in loadTestsFromNames
    suites = [self.loadTestsFromName(name, module) for name in names]
  File "/usr/lib/python2.7/unittest/loader.py", line 100, in loadTestsFromName
    parent, obj = obj, getattr(obj, part)
AttributeError: type object 'TestDownload' has no attribute 'test_NickBr'

Description

I've been trying to run a download test on the NickBrIE extractor contained in youtube_dl/extractor/nick.py, trying to fix an issue. Using the command python test/test_download.py TestDownload.test_NickBr and I'm unable to run it, although python test/test_download.py TestDownload.test_Nick works fine.

[dstftw]

NickBr does not have any download tests.