A Basic Testers Kit for USP API CCPA Compliance.

IABFrameworkTest.js

//  Instantiate a function immediately to stack trace for finding what vendors are leveraging the function
Function.prototype.clone = function() {
    var that = this;
    var temp = function temporary() { return that.apply(this, arguments); };
    for(var key in this) {
        if (this.hasOwnProperty(key)) {
            temp[key] = this[key];
        }
    }
    return temp;
};
window.__oldUsapi = window.__uspapi.clone();
window.__uspapi = function(){ 
  var args = Array.from(arguments);
  window.__oldUsapi.apply(null, args);
  try {
    throw new Error('foobar-usp');
  } catch (e){
    console.log('usp debug');
      console.debug(e.stack);
  }
};
// Log a postMessage attempt
var ccpaLog = function(event){ 
  if (event.data.__uspapiReturn){
    console.log('test CCPA in Ad Event ', 'value: ', event.data.__uspapiReturn , 'event: ', event); 
  }
 }
// Attempt a postMessage (this won't always work)
window.addEventListener(
"message", ccpaLog
);
console.log('CCPA Test postMessaged. Awaiting response. Sent to:', window.origin);
// Send a postMessage. This won't always trigger your debug depending on how the page has set up the uspapi interface. 
window.top.postMessage({
  __uspapiCall:
  {
    command: "getUSPData",
    parameter: 'foobar',
    version: 1,
    callId: 'testUniqueId'
  }
}, "*");
// Test the on-window object (this should also trigger your debug)
window.__uspapi('getUSPData', 1, function(uspData, success){console.log(uspData, success)});

This reason postMessage may not give you a debug dump is that some folks might implement their event listener by checking an on-page value instead of calling the window.__uspapi

Also, if you get the error Cannot read property 'clone' of undefined it is because the window level IAB function doesn't exist, in which case you might want to ask how your opt-out is registered.