Monitor all http(s) network requests using the Mozilla Platform

In an xpcshell test, I recently needed a way to monitor all network requests and access both request and response data so I can save them for later use. This required a little bit of digging in Mozilla’s devtools code so I thought I’d write a short blog post about it.

This code will be used in a testcase that ensures that calendar providers in Lightning function properly. In the case of the CalDAV provider, we would need to access a real server for testing. We can’t just set up a few servers and use them for testing, it would end in an unreasonable amount of server maintenance. Given non-local connections are not allowed when running the tests on the Mozilla build infrastructure, it wouldn’t work anyway. The solution is to create a fakeserver, that is able to replay the requests in the same way. Instead of manually making the requests and figuring out how the server replies, we can use this code to quickly collect all the requests we need.

Without further delay, here is the code you have been waiting for: