'Test the as_void() method'

def test_as_void(self, table_types):

    self._setup(table_types)
    table = self.t
    row = table[0]
    row_void = row.as_void()
    if table.masked:
        assert isinstance(row_void, np.ma.mvoid)
    else:
        assert isinstance(row_void, np.void)
    assert (row_void['a'] == 1)
    assert (row_void['b'] == 4)
    table['a'][0] = (-100)
    assert (row['a'] == (-100))
    assert (row_void['a'] == 1)
    if table.masked:
        table['a'].mask = True
        assert (row_void['a'] == 1)
        row_void = row.as_void()
        assert (row['a'] is np.ma.masked)
