The word "testing" offers room for several interpretations; basically, testing requires verifying the application's basic functionalities. However, there can be different types of tests depending on what you are testing and what environment you are using for testing.
The most common type of test is called a unit test and can be defined as a test written by the programmer to verify that a relatively small piece of code is doing what it is intended to do. Unit tests are narrow in scope; they should be easy to write and execute, and their effectiveness depends on what the programmer considers to be useful. These tests are intended for the use of the programmer; they are not directly useful to anybody else, though, if they do their job, testers and users downstream should benefit by seeing fewer bugs.
A more advanced type of test is called the integration test . Integration tests are done to demonstrate that different pieces of the system work together;...