When our programs don’t behave as expected, we need to investigate the source code. The traditional tool for code investigation is the debugger. The debugger allows us to run the code, step by step, until we find the line that causes the bug. However, a debugger doesn’t allow us to reproduce the scenario that causes the problem.
In DOP, we can capture the context of a scenario that causes a bug and replay it in a separate process like a REPL or a unit test. This allows us to benefit from a short feedback loop between our attempt to fix the code and the results of our attempt.
After a few months, Theo calls Dave to tell him that he’s leaving Albatross. After Dave recovers from this first surprise, he’s given another, more pleasant one. Theo informs Dave that after consulting with the management team, they have decided that Dave will be in charge of DOP at Albatross. In addition to the farewell at the office next week, Theo invites Dave for a last one-on-one work session at the Exploratorium Museum of Science.