'Directly test the virtual env detection function'

@pytest.mark.parametrize('fname', ('activate', 'activate.csh', 'activate.fish', 'Activate', 'Activate.bat', 'Activate.ps1'))
def test__in_venv(self, testdir, fname):

    bindir = ('Scripts' if py.std.sys.platform.startswith('win') else 'bin')
    base_path = testdir.tmpdir.mkdir('venv')
    assert (_in_venv(base_path) is False)
    base_path.ensure(bindir, fname)
    assert (_in_venv(base_path) is True)
