Unit tests are perhaps good for instilling a decent sense of function decomposition, but make no mistake, you can go too far in this direction and not develop the sense of an integrated system. It's a hard problem to avoid, especially when starting out. That's one of the reasons I generally find type-driven development better for seeing how parts are actually interacting.

Not to discount, testing, naturally, but I also prefer property based testing to unit for the same reason (i.e. a function can be a mini-system with relationships between internal values that may not be exposed with unit tests.)