Print debugging, but a little bit nicer.
The use case this is primarily designed for is effectively debugging problematic, flaky tests.
Use instead of fmt.Println, fmt.Printf, log.Println, log.Printf or $YOUR_FAVORITE_PRINT_FUNCTION.
On first write, testlog will create a log file if necessary.
If TESTLOG_PATH is specified, that path will be used for the log file, otherwise testlog will create a new file in your temporary file directory with testlog- prefix.
If you invoke testlog from multiple packages, say A and B, and you test them simultaneously via e.g. go test A B, testlog may be executed by two (or more) test processes simultaneously (go testing framework may run tests for A and B as two different processes), in which case it would write to two different log files if TESTLOG_PATH is not set.