When I access the funding instruments for an account for which no credit cards have been actually entered, I get a single funding instrument with a blank name and a description of “(no payment method has been set up yet)”. But I can use this funding instrument as though it was real, even in the production environment, and can even get to the point where I can make a campaign start running, according to the ads.twitter.com UI. A banner that says “Enter a credit card that will be used to pay for your advertising costs” persists, but I can still set the campaign as running.
What is the purpose of this funding instrument? Should I ignore it and advise my users to input a credit card at ads.twitter.com before using my app? If so, how do I detect this funding instrument reliably? There are no attributes that indicate that this is not a real credit card other than the description, and testing for equality on that text seems wrong.