Wrong 3P frame.html loaded when testing local compiled binary

All 3P frames are loading //ampproject.net/dist.3p/1513120604167/frame.html. This might be due to this change #12152 , which sets config.localDev=true, hence triggered the following logic in 3p-frame.js:

function getAdsLocalhost(win) {
  if (urls.localDev) {
    return `//${urls.thirdPartyFrameHost}`;
  }
  return 'http://ads.localhost:'
      + (win.location.port || win.parent.location.port);
}

To reproduce,

gulp dist --fortesting
gulp serve --fortesting --compiled

then load page http://localhost:8000/examples/ads.amp.html

[lannka]

I do expect localDev to be true (originally proposed here.

And I agree the fix should be somewhere getAdsLocalhost.

What is unclear to me is the current relation between getMode().LocalDev vs AMP_CONFIG.localDev.

If we can consolidate these 2 variables, then we can probably get rid of this getAdsLocalhost function.

[rsimha]

I agree that the logic is complicated. This is because the config is written during build time, and returned at runtime. I wonder how they can be consolidated without a file read.