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Dev MaxxingIntermediateTesting60 sec
Unit test
A unit test checks that one small, isolated piece of code, like a single function, behaves correctly for a given input.
What matters
Because unit tests check small pieces in isolation, they run quickly and pinpoint exactly where a bug lives, rather than only showing that something, somewhere, is broken.
Example
A unit test for an 'add(a, b)' function might check that 'add(2, 3)' returns exactly 5.
Common misconception
A unit test is not meant to verify how multiple parts of a system work together; that broader check is what integration tests are for.
Recall question
Why do unit tests pinpoint bugs more precisely than testing a whole system at once?
Keywords and related concepts
unit testisolated testingsoftware testingintegration test