How can functional programming simplify testing?

Functional programming can simplify testing in several ways. First, it promotes the use of pure functions, which always produce the same output for a given input, without any side effects. This predictability makes it easier to write tests that verify the behavior of functions. Second, functional programming emphasizes immutability, meaning that data is not changed once it is created. This makes it easier to reason about the state of your program and reduces the likelihood of bugs related to mutable state. Additionally, functional programming languages often support higher-order functions, which can be used to compose functions. This allows for more modular and testable code, as functions can be easily tested in isolation. Finally, functional programming promotes referential transparency, which means that a function call can be replaced with its value without changing the program’s behavior. This property makes code easier to understand and test, as the behavior of functions is more predictable.