loadBanner method
Loads a banner ad per spec.
Implementation
@override
Future<BannerHandle> loadBanner(BannerLoadSpec spec) async {
await _checkLoadAllowed('banner', spec.adUnitId);
loadLog.add('banner:${spec.adUnitId}');
bannerSpecs.add(spec);
final handle = FakeBannerHandle(
spec.adUnitId,
size: bannerSize,
isCollapsible: bannerIsCollapsible,
);
banners.add(handle);
return handle;
}