Keynote Speaker

Maaret Pyhäjärvi is an exploratory tester extraordinaire with a day-job at Vaisala as Principal Test Engineer. She is an empirical technologist, a tester and a (polyglot) programmer, a catalyst for improvement, a speaker and an author, and a community facilitator. She has been awarded the two prestigious global testing awards, Most Influential Agile Testing Professional Person 2016 (MIATPP) and EuroSTAR Testing Excellence Award (2020), and selected as Top-100 Most Influential in ICT in Finland 2019&2020. She’s spoken at events in 25 countries delivering over 400 sessions. With 25 years of exploratory testing under her belt, she crafts her work role into a mix of hands-on testing and programming, and leading and enabling others. She leads TechVoices enabling new speakers, blogs at and is the author of three books: Ensemble Programming Guidebook, Exploratory Testing and Strong-Style Pair Programming.

Title: Targeting Errors of Omission

Years ago, a manager asked me to be faster with testing. “Your colleague is working through many tests a day, and you’re not”. Comparing notes, we soon learned my colleague tested for big visible error messages whereas my theory of error - and results - was more versatile.


In years since, I have been improving my theories of error and understanding of risk, and come to notice a specific class of errors many colleagues in testing struggle with: errors of omission. While noticing something is there, like a big visible error message, is something people are good at, we need support in being good at seeing things that should be there but are not. While regression testing is a consideration of something going missing that used to be there, the most devious errors of omission are the things that are missing that should be there.


In this talk, we look through examples of omission, and tactics to improve our ability to see beyond what is there. In software development, we transform ideas to code, and our code is only as good as our ideas.