The test had two problems:
- the expected line was off by one (probably modified import statements)
- when Gomega failed in TestFailureOutput, Ginkgo panicked because
its fail handler was called outside of a Ginkgo node
Now github.com/stretchr/testify/assert is used for comparing the output because
it works in a unit test without further customization and because the failure
messages are more useful.
This continues the work in
https://github.com/kubernetes/kubernetes/pull/81426 by also moving the
logger_test.go, moving the log helper code from util.go to log.go (a
more logical place, as it is only used there) and updating comments.
