`tests.proofreadpage_tests.TestIndexPageMappingsRedlinks` fails is `bs4` is not installed. It should be skipped without throwing an error, like the other tests.
```
$ nosetests -v tests.proofreadpage_tests
Test IndexPage methods inherited from superclass BasePage. ... SKIP: bs4 not installed
Test ProofreadPage methods inherited from superclass BasePage. ... ok
Test IndexPage from invalid Site as source. ... SKIP: bs4 not installed
Test if cache is checked and loaded properly on wikisource:de ... SKIP: bs4 not installed
Test if cache is checked and loaded properly on wikisource:en ... SKIP: bs4 not installed
Test if cache is checked and loaded properly on wikisource:fr ... SKIP: bs4 not installed
Test IndexPage page get_label_from_* functions on wikisource:de ... SKIP: bs4 not installed
Test IndexPage page get_label_from_* functions on wikisource:en ... SKIP: bs4 not installed
Test IndexPage page get_label_from_* functions on wikisource:fr ... SKIP: bs4 not installed
Test IndexPage page get_page_number functions on wikisource:de ... SKIP: bs4 not installed
Test IndexPage page get_page_number functions on wikisource:en ... SKIP: bs4 not installed
Test IndexPage page get_page_number functions on wikisource:fr ... SKIP: bs4 not installed
Test num_pages property on wikisource:de ... SKIP: bs4 not installed
Test num_pages property on wikisource:en ... SKIP: bs4 not installed
Test num_pages property on wikisource:fr ... SKIP: bs4 not installed
Test Index page generator on wikisource:de ... SKIP: bs4 not installed
Test Index page generator on wikisource:en ... SKIP: bs4 not installed
Test Index page generator on wikisource:fr ... SKIP: bs4 not installed
ERROR
Test IndexPage from invalid existing Page as source. ... SKIP: bs4 not installed
Test IndexPage from invalid Link as source. ... SKIP: bs4 not installed
Test IndexPage from Page not existing in non-Page ns as source. ... SKIP: bs4 not installed
Test IndexPage from valid Link as source. ... SKIP: bs4 not installed
Test IndexPage from valid Site as source. ... SKIP: bs4 not installed
Test site.loadrevisions() with Page.text. ... SKIP: bs4 not installed
Test site.loadrevisions() with Page.text. ... ok
Test Page.quality_level when applicable. ... ok
Test index property. ... SKIP: bs4 not installed
Test ProofreadPage from invalid Site as source. ... ok
Test ProofreadPage page decomposing/composing text. ... ok
Test ProofreadPage from invalid existing Page as source. ... ok
Test ProofreadPage from invalid Link as source. ... ok
Test ProofreadPage from invalid not existing Page as source. ... ok
Test ProofreadPage from Page not existing in non-Page ns as source. ... ok
Test conversion to json format. ... ok
Test ProofreadPage page decomposing/composing text. ... ok
Test ProofreadPage page decomposing/composing text. ... ok
Test ProofreadPage from valid Link as source. ... ok
Test ProofreadPage page parsing functions. ... ok
Test ProofreadPage from valid Site as source. ... ok
======================================================================
ERROR: test suite for <class 'tests.proofreadpage_tests.TestIndexPageMappingsRedlinks'>
----------------------------------------------------------------------
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/nose/suite.py", line 208, in run
self.setUp()
File "/usr/lib/python2.7/dist-packages/nose/suite.py", line 291, in setUp
self.setupContext(ancestor)
File "/usr/lib/python2.7/dist-packages/nose/suite.py", line 314, in setupContext
try_run(context, names)
File "/usr/lib/python2.7/dist-packages/nose/util.py", line 471, in try_run
return func()
File "/home/ajk/Documents/wiki/pywikibot-core/tests/proofreadpage_tests.py", line 572, in setUpClass
cls.index = IndexPage(cls.site, cls.index_name)
File "/home/ajk/Documents/wiki/pywikibot-core/pywikibot/proofreadpage.py", line 451, in __init__
raise BeautifulSoup
ImportError: No module named bs4
----------------------------------------------------------------------
Ran 39 tests in 15.207s
FAILED (SKIP=24, errors=1)
```