def test_set_scalar_subset_X(matrix_type, subset_func):
    adata = ad.AnnData(matrix_type(np.zeros((10, 10))))
    orig_X_val = adata.X.copy()
    subset_idx = slice_subset(adata.obs_names)

    adata_subset = adata[subset_idx, :]

    adata_subset.X = 1

    assert adata_subset.is_view
    assert np.all(asarray(adata[subset_idx, :].X) == 1)

    assert asarray((orig_X_val != adata.X)).sum() == mul(*adata_subset.shape)
def union(matches, root, cwd):
    """Union a list of matchers.

    If the list is empty, return nevermatcher.
    If the list only contains one non-None value, return that matcher.
    Otherwise return a union matcher.
    """
    matches = list(filter(None, matches))
    if len(matches) == 0:
        return nevermatcher(root, cwd)
    elif len(matches) == 1:
        return matches[0]
    else:
        return unionmatcher(matches)