They have oil, gas, minerals, and a home grown industry. Access to a few financial instruments/tricks of the Wall Street will not bring any real benefit to an average Iranian citizen.
If Iran tests the nuke they can solve many, many issues, the ones they are experiencing as well as the ones they do not even see or comprehend yet. There will be no pressure from Russia or China on Iran. They will not pause any economic activity with Iran over it even for one hour let alone stopping it.
If the Mullahs still do not test their nukes now, it means there is something else completely sinister is going on here.