UML specification defines two major kinds of UML diagram: structure diagrams and behavior diagrams.

Structure diagrams show the static structure of the system and its parts on different abstraction and implementation levels and how they are related to each other. The elements in a structure diagram represent the meaningful concepts of a system, and may include abstract, real world and implementation concepts.

In UML you design diagrams that can contain different elements of the software, for example, the most common is the one where you write the name of the class, its attributes and its methods. But it all depends of the diagram you use. In UML there are many different diagrams with different uses and elements that you can write.

Is not necessary to become an expert of UML because is not actually a must for learning actual coding, but is important to know about it because it helps in the design part of software. Creating an UML diagram is like drawing a sketch, is not that important and is unnecessary to put much effort on it, just with understanding the idea is enough.

There are many UML diagrams (13 to be exactly) so in the next section there are only the three most important.

Benefits of using UML:

• Improves development time
• Establishes concepts and executables
• Creates a modeling language used by humans and machines
• Improves support and control for project management
• High reuse and reduced costs
• Models systems using object oriented concepts

James Gosling slings a pie in the face of a Bill Gates impersonator.

Software testing is actually something that we have always done since we learned how to program, we have used it homework and projects from program classes, for example, in fundamentals of programing and POO. The purpose of testing is to verify that your program o software is doing or it does exactly what is intended to do and also to look for bugs that happens on particular cases.

“JUnit promotes the idea of “first testing then coding”, which emphasizes on setting up the test data for a piece of code that can be tested first and then implemented”

In java, JUnit is  used as a library by importing the necessary classes an then creating a constructor of the test and implementing methods that call an instance of the class you want to test that are used to execute specific method of the tested class. The goal for each of those testing methods is to assert the expect behavior comparing the the expected value and the actual value. You can use any data type: from data primitive (such as int, char, float, etc.) to arrays of any type, any objects and nulls.

A Unit Test Case is a part of code, which ensures that another part of code (method) works as expected. To achieve the desired results quickly, a test framework is required and JUnit is perfect for that.

A formal written unit test case is characterized by a known input and an expected output, which is worked out before the test is executed. The known input should test a precondition and the expected output should test a post-condition.

There must be at least two unit test cases for each requirement − one positive test and one