Checks if the test program is available in the python environnement

def check_dependencies(self):
        "Checks if the test program is available in the python environnement"
        if self.test_program == 'nose':
            try:
                import nose
            except ImportError:
                sys.exit('Nosetests is not available on your system. Please install it and try to run it again')
        if self.test_program == 'py':
            try:
                import py
            except:
                sys.exit('py.test is not available on your system. Please install it and try to run it again')
        if self.test_program == 'django':
            try:
                import django
            except:
                sys.exit('django is not available on your system. Please install it and try to run it again')
        if self.test_program == 'phpunit':
            try:
                process = subprocess.check_call(['phpunit','--version']) 
            except:
                sys.exit('phpunit is not available on your system. Please install it and try to run it again')
        if self.test_program == 'tox':
            try:
                import tox
            except ImportError:
                sys.exit('tox is not available on your system. Please install it and try to run it again')