A tweet from Ward Cunningham yesterday led me to watch a very interesting video of a lunch time demo of exploratory testing by Elisabeth Hendrickson , while visiting Pivotal Labs. Ms Hendrickson shows how she forms a model of how the software works in order to find issues more productively. During the session someone says that they always heard that testers should be like typical "dumb" users and treat the software as a black box, but Elisabeth says that getting information about the actual implementation from the developers is fine. She also talks about her process of forming hypotheses about how the system works, and doing experiments which confirm or refute those hypotheses.

Does this sound familiar? We're talking about the scientific method here. In an interesting coincidence, I also stumbled upon another web video this weekend, an interview in which Richard Feynman describes science with an analogy of learning the rules of chess, simply by observing games being played, with no explanation.

I found myself thinking about the roles of the exploratory test. It seems to me that one of these roles is to act as a mock for the end user.

And despite the common epigram, users are usually far from dumb. A typical user forms a mental model of how a system operates, and use that to inform their use of the system. The model starts from a base of expectations about how similar systems operate, and the user adapts the model as he/she encounters behavior which doesn't fit. Very much like Feynman's hypothetical chess student, who first observes that Bishops only move to squares of the same color, and Kings move one square, and then has to adapt the model when they encounter a pawn being promoted to a Bishop, or castling.

When the user's model and the implementation model don't align, interesting things can happen, often unpleasant. It's usually desirable to eliminate such misalignments, and the conversations between an exploratory tester and a developer about misapprehensions about how either the system or the user works are valuable in achieving this.

The scientific method is also useful for exploratory development, such as when writing code which interfaces with or implements a complex API or standard, but that's fodder for a future article.