def test_view_of_view(matrix_type, subset_func, subset_func2):
    adata = gen_adata((30, 15), X_type=matrix_type)
    adata.raw = adata
    if subset_func is single_subset:
        pytest.xfail("Other subset generating functions have trouble with this")
    var_s1 = subset_func(adata.var_names, min_size=4)
    var_view1 = adata[:, var_s1]
    var_s2 = subset_func2(var_view1.var_names)
    var_view2 = var_view1[:, var_s2]
    assert var_view2._adata_ref is adata
    obs_s1 = subset_func(adata.obs_names, min_size=4)
    obs_view1 = adata[obs_s1, :]
    obs_s2 = subset_func2(obs_view1.obs_names)
    assert adata[obs_s1, :][:, var_s1][obs_s2, :]._adata_ref is adata

    view_of_actual_copy = adata[:, var_s1].copy()[obs_s1, :].copy()[:, var_s2].copy()

    view_of_view_copy = adata[:, var_s1][obs_s1, :][:, var_s2].copy()

    assert_equal(view_of_actual_copy, view_of_view_copy, exact=True)
def _regex(kind, pat, globsuffix):
    """Convert a (normalized) pattern of any kind into a regular expression.
    globsuffix is appended to the regexp of globs."""
    if not pat and kind in ("glob", "relpath"):
        return ""
    if kind == "re":
        return pat
    if kind in ("path", "relpath"):
        if pat == ".":
            return ""
        return util.re.escape(pat) + "(?:/|$)"
    if kind == "rootfilesin":
        if pat == ".":
            escaped = ""
        else:
            # Pattern is a directory name.
            escaped = util.re.escape(pat) + "/"
        # Anything after the pattern must be a non-directory.
        return escaped + "[^/]+$"
    if kind == "relglob":
        return "(?:|.*/)" + _globre(pat) + globsuffix
    if kind == "relre":
        if pat.startswith("^"):
            return pat
        return ".*" + pat
    return _globre(pat) + globsuffix