This chapter JUnit Tutorial demonstrate about the Unit testing, the application with JUnit. JUnit is a system that can be utilized to perform the unit writing, so as to test the programming experiments in Java. JUnit is one of the group of a unit testing structures and is known as XUnit that originated with JUnit. Following are the concepts covered.

• What is Testing?
• Types of Testing?
• JUnit
• How JUnit Works?
• Unit Testing
• Unit Testing Uses

Testing is a process of finding the bugs in a program or application and also known as process of finding the difference between the expected output and actually given input. Testing evaluates the quality of the product which is done by testing team during the development process of the project. For maintaining and developing the projects Software Development Life Cycle (SDLC) was very useful for all software projects. The image below demonstrate life cycle of SDLC.

In order to describe the types of testing basically testing can be divided in to two types based on SDLC.

• Manual Testing
• Automation Testing

Manual Testing is the testing used to test the program or application manually means without using any additional tool. Following are some of the Manual Testing methods some methods are described below. In order to test the software project or application developer need to use the some of the test Scripts and test cases or test scenarios for complete testing process. The below image demonstrate about Manual Testing.

Automation testing is a process of testing an application by using software tools which is done before the deployment stage or also known as re running the manual testing quickly and repeatedly by using the some tools. The below image demonstrate the automation testing process.

JUnit is intended to be a unit testing outline work for Java. JUnit is packaged as a single JAR file, it basically have a library of functionality which makes easier for a developer to create unit test in Java and verify the results of those tests. Client cannot utilize JUnit to do unit test in Java. So in order to do unit test in Java developer need to make own unit test code to tests the code. JUnit frame work do not test by itself but gives an easy way to create tests and a way to run those tests, so creating tests is a development activity more than a testing activity.

The author of the JUnit is Kent Beck. He is the one of the authors of the Aglie Manifesto that began the Agile Movement and also known as the father of extreme programing. JUnit was created by Knet Beck and Gamma were JUnit actually follows JUnit roots, which was a Unit testing outline work created to use with the own compiling programming philosophy in each line of generation. Kent Beck later made JUnit unit testing tool for unit testing Java code.

Most of the people's utilized and right now utilizing the JUnit for the purpose of unit testing to test the Java code. Users may or may not know about each and every component of the JUnit. So, following are some of  components of JUnit. JUnit has the ability to integrate with most of the popular build systems for Java including Ant and Maven.

JUnit is used to compose some content code, the most part of the code is composed from different projects and is known as Subject under test(SUT). The most part of SUT is a Java class, JUnit can be utilized for the unit testing. The Test code capabilities of JUnit Framework make it easier to analyze the outcomes and different things like Setting up and Tearing down tests. JUnit runner is used to see the running test and figure out what test exist and how it ought to run them and report those outcomes.

Unit testing is a simple concept. The center of the JUnit is not a Unit testing, Unit testing is the fundamentals of the unit testing and how the JUnit functions. The essential test behind Unit testing is to take the smallest code and test it without anyone else. A Unit is a smallest testable part of an application like Functions, classes, strategies. In a Unit testing set of inputs are given then it ought to give back the best possible values and additionally it ought to handle the failures doing the execution of the code.

The below figure demonstrates the whole framework of wide range of classes that are assembled together as various parts, smallest unit is a single class.

Unit testing was most useful while performing the testing, following are the few uses described below

• Instant Satisfaction Unit testing is a power full tool which allows to execute the developed code and also describe about the working of the code instantly.

• Help in Designing Unit testing will help in the designing process of API and also tells using of classes in a test methods Which is also help full in naming conventions it leads to the good design.

• How Code Works Unit test will explores which code is running perfectly and how it is performing in test cases.

• JUnit Tutorial - JUnit mostly used in a test driven development and it is likewise group of a testing structure.
• JUnit Tutorial - JUnit is used to handle all the levels of Java projects.
• JUnit Tutorial - JUnit tool consist of so many features to test the Java projects.
• JUnit Tutorial - JUnit is not necessary to do unit test in Java.