Build a simulator for any feature: Unit testing | Algolia

The text discusses automated testing, specifically unit tests, which are small pieces of code that verify a function's correctness. Unit tests are crucial in modern development due to the modularity principle, where large tasks are broken down into smaller functions. These smaller functions can be pure functions, which always return the same output for a given input and do not affect or get affected by anything outside of the function. Pure functions are straightforward to test since we can simulate their usage and check the output against expected results. The text provides an example of how unit tests can help identify bugs in code. It also explains how to handle non-pure functions, which involve side effects or aren't deterministic. In such cases, developers should refactor the function into smaller pure functions that are easier to test. The text concludes by mentioning that testing UI elements and entire workflows is more complex and requires different strategies, which will be discussed in part 2 of this series.