TIL: badssl.com lets you test bad certificates

While working on Slack’s unfurl previews I needed to test what happens when the fetcher cannot access a site. People put a lot of different URLs into Slack; some of them are going to be unfetchable for various reasons. Pointing the fetcher at a URL that doesn’t resolve, or one that results in a timeout, is straightforward, but I don’t know enough to set up various bad SSL/TLS scenarios. Surely one…