'Test indexing and slicing on Layers.'

def test03b_layer_slice(self):

    source = ds_list[0]
    ds = DataSource(source.ds)
    sl = slice(1, 3)
    feats = ds[0][sl]
    for fld_name in ds[0].fields:
        test_vals = [feat.get(fld_name) for feat in feats]
        control_vals = source.field_values[fld_name][sl]
        self.assertEqual(control_vals, test_vals)
