Writing testable code

The document discusses writing testable code. It begins by introducing the speaker and then discusses challenges with writing tests, such as determining what and how much to test. It notes unit testing only tests individual units and not integration or system-level errors. The document advocates for writing pure, composable functions without side effects that are easily testable. It discusses lessons from functional programming like separating pure from impure code and using types properly. Overall, the document argues for writing code in a functional style to enable better testing.