TestPylabSwitch.test_qt fails

[takluyver]

I see this in 2.7 and 3.3

======================================================================
FAIL: IPython.core.tests.test_pylabtools.TestPylabSwitch.test_qt
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/home/takluyver/.virtualenvs/ipy-trunk/local/lib/python2.7/site-packages/IPython/core/tests/test_pylabtools.py", line 96, in test_qt
    nt.assert_equal(gui, 'qt')
AssertionError: 'tk' != 'qt'
    "'tk' != 'qt'" = '%s != %s' % (safe_repr('tk'), safe_repr('qt'))
    "'tk' != 'qt'" = self._formatMessage("'tk' != 'qt'", "'tk' != 'qt'")
>>  raise self.failureException("'tk' != 'qt'")

With Python 2 (but not Python 3), I also see this, potentially related, warning (EDIT: the warning is due to sympy 0.7.2, but it does not appear to be connected to the test failure):

/usr/lib/pymodules/python2.7/matplotlib/__init__.py:1143: UserWarning:  This call to matplotlib.use() has no effect
because the the backend has already been chosen;
matplotlib.use() must be called *before* pylab, matplotlib.pyplot,
or matplotlib.backends is imported for the first time.

  warnings.warn(_use_error_msg)

[jenshnielsen]

The warning could be related to #2035 and the fact that sympy 0.7.2 is installed. Sympy is imported due to the skip if not sympy decorator and importing sympy selects a backend due to the ploting module breaking the selection of backend in the testss However this should be fixed in sympy 0.7.3. Other package imports may have a similar effect.

[takluyver]

You're right, upgrading sympy makes the warning disappear, but the test failure is still there. I guess they're separate.