Machine-Coding Interviews
Deliver a runnable, testable core before investing in optional framework features. The quality of the public contract matters more than the number of classes created under time pressure.
What you’ll understand
- Deliver a runnable, testable core before investing in optional framework features. The quality of the public contract matters more than the number of classes created under time pressure.
- Practice explaining a design decision with an example and a boundary case.
Make the core callable
Write a domain entry point such as machine.act(action) or lot.park(vehicle). Keep console parsing and printing outside that operation. A test should be able to construct the model and inspect a result without pretending to be a user typing into a terminal.
- Choose deterministic IDs or inject an ID source.
- Return results instead of printing inside every method.
- Keep dependencies replaceable for tests.
Implement in thin increments
Make the first useful action work, then add one rejection case and one state transition at a time. Run the program often. If stock can become negative, solve that invariant before adding a polished command-line menu. Small increments expose misunderstandings while there is still time to correct them.
- Create, use, and inspect one entity.
- Exercise invalid input and repeated operations.
- Add a second collaborator only when a requirement uses it.
Finish with evidence
Reserve time to explain what runs, which tests pass, and which requirements are intentionally excluded. A useful handoff includes an example input sequence, expected output, and the assumptions that make it correct.
- Can a reviewer run the main flow in one command?
- Does a failed operation preserve prior state?
- What would you implement next with another hour?