'``create_virtualenv`` installs a virtual python environment in its
``target_path``.'

def test_bin(self):

    virtualenv = VirtualEnv(root=FilePath(self.mktemp()))
    InstallVirtualEnv(virtualenv=virtualenv).run()
    expected_paths = ['bin/pip', 'bin/python']
    assert_has_paths(self, expected_paths, virtualenv.root)
