visibleForTesting top-level constant
Used to annotate a declaration was made public, so that it is more visible than otherwise necessary, to make code testable.
Tools, such as the analyzer, can provide feedback if
the annotation is associated with a declaration not in the
of a package, or
the declaration is referenced outside of its the defining library or a
library which is in the
test folder of the defining package.
const _VisibleForTesting visibleForTesting = const _VisibleForTesting()