Have you used functional interfaces in your projects?

Functional interfaces are interfaces with a single abstract method, widely used in programming languages that support functional style, such as Java (Runnable, Callable, Function<T,R>, etc.).

In testing automation projects, functional interfaces are often used to pass behavior as parameters, for example, lambda expressions for handling results, filtering data, or configuring tests.

Example of using a functional interface in Java:

import java.util.function.Function;

public class Example {
    public static void main(String[] args) {
        Function<String, Integer> lengthFunc = s -> s.length();
        System.out.println(lengthFunc.apply("test")); // Outputs 4
    }
}

Thus, functional interfaces allow writing more flexible and concise code, which is useful in automation testing and other tasks.