Add more tests to increase code coverage

Currently the code in `/features` contains very basic tests. Only the "happy" paths. We should add extensive tests which strives to execute each and every execution path.

Also as discussed previously, we need to be more strict about "No new features without tests" policy.

This might reduce our speed initially but will definitely help us in long run. Also we should look into code coverage tools to gauge how many execution paths are being tested.