Getenv calls Logger().Getenv, if a logger has been set.

Logger returns the current test logger implementation.

Open calls Logger().Open, if a logger has been set.

PanicOnExit0 reports whether to panic on a call to os.Exit(0).

SetLogger sets the test logger implementation for the current process.

SetPanicOnExit0 sets panicOnExit0 to v.

Stat calls Logger().Stat, if a logger has been set.

Interface is the interface required of test loggers.