Tox and django_toolbar: ImportError
Question: When trying to use Tox to better streamline testing across multiple
environments, I'm runing into the following error when testing for Python 3.4:

`ImportError: No module named 'debug_toolbar'`

However, `django-debug-toolbar==1.3.0` is listed in my `requirements.txt`
file, and my `tox.ini` file looks as follows:

    
    
    [tox]
    envlist = py27,py34
    skipsdist = True
    
    [testenv]
    deps = -r{toxinidir}/requirements.txt
    setenv =
        PYTHONPATH = {toxinidir}:{toxinidir}
    commands = python manage.py test
    

It seems as if it is not properly installing the requirements.. Oddly enough,
the py27 environment does not throw this error, and is able to perform the
tests just fine.

What could be causing this?

EDIT: for reference, here's my current setup. When I run tox the first time
(i.e. without .tox), it works fine, but any times after that it fails. The
`.tox` directory does seem to get build up correctly; all dependencies are
installed in `.tox/py34/lib/python3.4/site-packages`. Compared to earlier, I
now also uninstalled `django`, and indeed that is now the first dependency
that fails.

    
    
    (venv)joost@thorin:myproject/ (master✗) % rm -rf .tox
    (venv)joost@thorin:myproject/ (master✗) % cat tox.ini
    [tox]
    envlist = py27,py34
    skipsdist = True
    
    [testenv]
    deps = -r{toxinidir}/requirements.txt
    commands = python manage.py test
    
    
    (venv)joost@thorin:myproject/ (master✗) % tox
    py27 create: /Users/Joost/myproject/.tox/py27
    py27 installdeps: -r/Users/Joost/myproject/requirements.txt
    py27 runtests: PYTHONHASHSEED='4248725049'
    py27 runtests: commands[0] | python manage.py test
    Creating test database for alias 'default'...
    ................
    ----------------------------------------------------------------------
    Ran 16 tests in 0.093s
    
    OK
    Destroying test database for alias 'default'...
    py34 create: /Users/Joost/myproject/.tox/py34
    py34 installdeps: -r/Users/Joost/myproject/requirements.txt
    py34 runtests: PYTHONHASHSEED='4248725049'
    py34 runtests: commands[0] | python manage.py test
    Creating test database for alias 'default'...
    ................
    ----------------------------------------------------------------------
    Ran 16 tests in 0.093s
    
    OK
    Destroying test database for alias 'default'...
    ____________________________________________________________________ summary _____________________________________________________________________
      py27: commands succeeded
      py34: commands succeeded
      congratulations :)
    
    
    (venv)joost@thorin:myproject/ (master✗) % tox
    py27 runtests: PYTHONHASHSEED='3259360769'
    py27 runtests: commands[0] | python manage.py test
    Creating test database for alias 'default'...
    ................
    ----------------------------------------------------------------------
    Ran 16 tests in 0.088s
    
    OK
    Destroying test database for alias 'default'...
    py34 runtests: PYTHONHASHSEED='3259360769'
    py34 runtests: commands[0] | python manage.py test
    Traceback (most recent call last):
      File "manage.py", line 8, in <module>
        from django.core.management import execute_from_command_line
    ImportError: No module named 'django'
    ERROR: InvocationError: '/Users/Joost/myproject/.tox/py34/bin/python manage.py test'
    ____________________________________________________________________ summary _____________________________________________________________________
      py27: commands succeeded
    ERROR:   py34: commands failed
    (venv)joost@thorin:myproject/ (master✗) % 
    


Answer: In the end, this was solved by upgrading `tox`. I'm not sure yet when this was
fixed exactly, or what bug it was listed as, but using version `2.1.1` I do
not get this error any longer.

