Unit Test
You might say
Add unit tests for price calculation: 100 gets 20 off, 99 does not, and external payment must not participate.
A unit test tests one independently verifiable function, component, or small module.Pass a fixed price to a tax function and assert the amount, or check that a disabled button does not submit. It isolates outside services so a failure points to a small responsibility. A full login with browser, API, and real database is not a unit test.
Also calledUT
Further reading