Tests coverage is gathered for _test_util.go files

[dimitar-dimitrow]

When executing the unit tests go test ./... -coverprofile=coverage.out -covermode count -tags=unit there are entries for _test_util.go files in coverage.out - cat coverage.out | grep _test_util.go. Those files are not expected to be covered as they are for testing purposes and they should not included them in the coverage report.