You could run the Parsedown testsuite only with:
phpunit --testsuite ParsedownTests
And you could run the Standard Markdown one with:
phpunit --testsuite StandardMarkdown
See more at http://standardmarkdown.com/
Tests are using the Composer autoloader since: cd1c030362
Because of that Composer should have actually dumped the autoloader in the `vendor/` folder,
before the tests are ran.