I believe it is both. Like much of engineering, there are rules and best practices that guide the field (science) while plenty of room for added intuition (art). There is plenty of basic blocking and tackling that can be self taught but you can quickly get into situations where you can benefit from the prior experience of others. Once you begin to scale your efforts, this is definitely essential. But all along, there is room for innovation, creativity and vision.

Completely agree with Tom here - there are patterns & approaches built from studying trends + statistics over time making it science-based. For me the fun part is going in + trying to break stuff akin to playing a game in more of an arty, playful style.

25 years ago I was convinced by Jerry Weinberg to call it a craft. That has felt consistently comfortable over the years.

There is considerable science behind the craft of testing, although very VERY few testers know much about that science.

If you’d like to learn more about the science behind testing, you will have to delve into these fields:

• Epistemology
• Philosophy/History of Science
• Sociology/Psychology
• Cognitive Science
• Rhetoric/Critical Analysis
• Certain branches of mathematics: statistics, set theory, discrete mathematics, combinatorics.

Consider also that it is more interesting to say “testing IS science” than to say that testing is A science. What scientists do-- what it literally means to think like a scientist-- is exactly what good testers must do.

The fact that testing IS science, explains why engineers are so uncomfortable with it. Engineers want to get things done. Engineering is finite. But science goes on and on. Scientists just keep asking questions and pursuing experiments.