Bod, thanks for taking the time to post a clear, well thought-out question that's provoked so many excellent replies!

In case you want to learn more of the history and culture behind Perl's widely admired testing infrastructure, Perl CPAN test metadata describes:

• The Oslo Consensus (May 2008)
• The Lancaster Consensus (April 2013)
• The Berlin Consensus (2015)
• PTS Oslo (2018) - see notes from the review at PTS 2018 Oslo

... looking forward to a future (working class) Coventry Consensus. :)

Updated: Added links for Oslo Consensus, Lancaster Consensus, Berlin Consensus (thanks Tux). Hope I got the definitive links. :)