Increase test coverage

[0xgouda]

Our current test coverage is generally "low", observing the latest coveralls builds, we can see that the reaper and sinks packages are the lowest ones and hence should have more unit tests to increase their coverage.

The added tests should cover all scenarios; therefore, adding integration tests (which won't affect coverage) should also be considered.

[pashagolub]

Yes, this should be improved for sure! I'd split it into two separate PRs though.