def METHOD_NAME(app):
    # regression test for #976
    app.builder.build(['index_entries'])
    pot = (app.outdir / 'index_entries.pot').read_text(encoding='utf8')
    msg_ids = list(filter(None, map(msgid_getter, pot.splitlines())))
    assert msg_ids == [
        "i18n with index entries",
        "index target section",
        "this is :index:`Newsletter` target paragraph.",
        "various index entries",
        "That's all.",
        "Mailing List",
        "Newsletter",
        "Recipients List",
        "First",
        "Second",
        "Third",
        "Entry",
        "See",
    ]