In this article, we will learn two things, how to implement a linked list from scratch in Java and how to write a unit test using JUnit framework. Though Java has LinkedList class, which is an implementation of the doubly linked list, its good to know how to implement singly linked list in Java, mostly to practice coding interview questions. Coming to back to writing a unit test, from time to time, I have said that a Java programmer must write unit tests. IMHO, unit testing is the best development practice to improve code quality. Fortunately, Java ecosystem has the luxury of great unit testing frameworks in form of JUnit and TestNG, and every Java developer should take advantage of this.