Functional test code coverage is broken

[yatki]

Expected behavior

Code coverage must be provided after running functional tests

Actual behavior

Code coverage report is empty at the moment.

Steps to reproduce

1. NODE_ENV=test node src/index.js
2. Run functional tests.
3. Run commands below:

curl --silent http://localhost:4000/coverage/download --output functional-coverage.zip
unzip functional-coverage.zip lcov.info -d functional/

lcov.info is empty

Which version(s) does this affect? (Environment, OS, etc...)

1.6.0+