Start with this example
Write percentageChange(before, after). 100 → 125 = 25 100 → 80 = -20 0 → 10 = an explicit error
Give your assistant a clear brief
Use a compatible tool you already have, or choose a reviewed guide below. This is a suggested learning exercise, not proof that a specific installation has been tested.
In a disposable project, write a percentageChange(before, after) function with tests. Return the percentage increase or decrease as a number. 100 to 125 must return 25; 100 to 80 must return -20. Reject a zero starting value with an explicit error. Run the tests and show the results. Do not add dependencies unless required.
Check the result
Read the tests and run them yourself. Confirm that the zero case fails explicitly rather than returning Infinity. A tool saying “tests pass” without runnable tests is not the result.
What to take away
Acceptance examples narrow the task and make the result independently checkable.
