Install the app in a device and go to course contents. Open a module that's not downloaded (mini-site resource, book, imscp, page). Wait for it to be rendered and go back to module list. Check that the download icon is gone. Do the same as above, but go back before the file is rendered. You should see the downloading spinner, and it should disappear when all the files are downloaded. Click a not downloaded mod_resource that's not a mini site. If you go back to the modules list you should still see the download icon, since the file is not downloaded yet. Click the "open file" button in the mod_resource, go back to the module list and check that the download icon is gone.