This test verifies that the inialization logic does not accidentally
execute the lazy initialization logic that is intended to only evaluate
upon first use.
Change-Id: I5e9dea17ce88081c78195af0e86dd38223689f63
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/184259
Reviewed-by: Damien Neil <dneil@google.com>
