void test_open_with_config ()
{
    // N.B. This function must run after ImageBuf_test_appbuffer, which
    // writes "A.tif".
    ImageCache *ic = ImageCache::create(false);
    ImageSpec config;
    config.attribute ("oiio:DebugOpenConfig!", 1);
    ImageBuf A ("A.tif", 0, 0, ic, &config);
    OIIO_CHECK_EQUAL (A.spec().get_int_attribute("oiio:DebugOpenConfig!",0), 42);
    ic->destroy (ic);
}