Can we test it? Yes, we can! - Mitchell Hashimoto

Mitchell Hashimoto discusses the challenges of testing complex software like Ghostty, a GPU-rendered terminal emulator, and shares strategies for testing the untestable.

As the co-founder of HashiCorp, Mitchell has been instrumental in the development of tools that many of us use daily, like Vagrant, Terraform, Vault, and more. He also helped shape the initial testing strategies for them, gaining hard-won insights into testing complex software along the way. At BugBash, where everyone is a testing nerd (or at least wants to be), most of us have come across that one piece of code that cannot be tested. What do you do when the code you so eagerly want to test is not testable? While working on his latest passion project, Ghostty, Mitchell came across this challenge again and again. For instance, Ghostty is a GPU rendered terminal emulator that demands GPU testing. In the age of AI, it’s surprising that we don’t yet have a broadly accepted solution for this – at least, not one that’s cracked the first page of google. So Mitchell’s talk is his (current best) answer to a deceptively simple question, “How do you make something testable?” Expanding the boundaries of testing drives the work at Antithesis too. So, the good news/bad news is, there are fewer and fewer reasons to leave any code untested. antithesis.com/blog/2025/bugbash_2025/mitchell_hashimoto/