automate electron based desktop app using testcafe not working

i am trying to automate tests for 'lens' electron based desktop application.i was following this link enter link description here to setup the test for electron app.This link expects a 'mainwindowurl' but application doesn't have any main page, but testcafe give suggestion of the mainwindowurl as an error so tried it works but am not convinced with the suggrstion urls ,but same way want to give fixture page url on the test what should be the url should i need to give? then have got one more error ERROR Unable to establish one or more of the specified browser connections. This can be caused by network issues or remote device failure.Please can you guys suggest what to do?