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 _handle_signal_gracefully(cls, signum, signame, traceback_lines):
        """Signal handler for non-fatal signals which raises or logs an error and exits with
        failure."""
        # Extract the stack, and format an entry to be written to the exception log.
        formatted_traceback = cls._format_traceback(
            traceback_lines=traceback_lines, should_print_backtrace=True
        )
        signal_error_log_entry = cls._CATCHABLE_SIGNAL_ERROR_LOG_FORMAT.format(
            signum=signum, signame=signame, formatted_traceback=formatted_traceback
        )
        # TODO: determine the appropriate signal-safe behavior here (to avoid writing to our file
        # descriptors re-entrantly, which raises an IOError).
        # This method catches any exceptions raised within it.
        cls.log_exception(signal_error_log_entry)

        # Create a potentially-abbreviated traceback for the terminal or other interactive stream.
        formatted_traceback_for_terminal = cls._format_traceback(
            traceback_lines=traceback_lines,
            should_print_backtrace=cls._should_print_backtrace_to_terminal,
        )
        terminal_log_entry = cls._CATCHABLE_SIGNAL_ERROR_LOG_FORMAT.format(
            signum=signum, signame=signame, formatted_traceback=formatted_traceback_for_terminal
        )
        # Exit, printing the output to the terminal.
        cls._exit_with_failure(terminal_log_entry)