def test_set_index_raises_error_on_bad_input():
    df = pd.DataFrame({'a': [1, 2, 3, 4, 5, 6, 7], 'b': [7, 6, 5, 4, 3, 2, 1]})
    ddf = dd.from_pandas(df, 2)
    msg = 'Dask dataframe does not yet support multi-indexes'
    with pytest.raises(NotImplementedError) as err:
        ddf.set_index(['a', 'b'])
    assert (msg in str(err.value))
    with pytest.raises(NotImplementedError) as err:
        ddf.set_index([['a', 'b']])
    assert (msg in str(err.value))
    with pytest.raises(NotImplementedError) as err:
        ddf.set_index([['a']])
    assert (msg in str(err.value))
def test_set_index_raises_error_on_bad_input():
    df = pd.DataFrame({'a': [1, 2, 3, 4, 5, 6, 7], 'b': [7, 6, 5, 4, 3, 2, 1]})
    ddf = dd.from_pandas(df, 2)
    msg = 'Dask dataframe does not yet support multi-indexes'
    with pytest.raises(NotImplementedError) as err:
        ddf.set_index(['a', 'b'])
    assert (msg in str(err.value))
    with pytest.raises(NotImplementedError) as err:
        ddf.set_index([['a', 'b']])
    assert (msg in str(err.value))
    with pytest.raises(NotImplementedError) as err:
        ddf.set_index([['a']])
    assert (msg in str(err.value))