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What are Unit Testing, Integration testing and Functional testing

There are many types of testing you can use to make sure that various changes you made in your code are working fine or not. Every type of testing has its purpose and significance in the software testing life cycle. And today we are here to know what is the nature and function of three types of testing which are unit testing, integration testing and functional testing.

Being a developer or tester, you must know which are the various testing cycles available to help you to make your website or application error free. To know about the testing process is not only important for the tester but also the developer’. They must know what is going on with application on the testing and which are the various techniques. So let’s know the various testing techniques available and what their significance is.

Unit testing

Unit testing is a method of testing where a small piece of code or module is tested with the help of individual functions. The test comes at the first stage of software testing life cycle and software development life cycle. Unit test link checks whether the specific module or piece of code is working fine or not. Suppose if you have a big application to test and you are completed with its first module then you must check whether the module is working fine or not as per the requirement specification. If you do not perform unit testing, then you may face more complications in other phases of testing.

A unit test must be simple and should focus on checking the function of the module according to the various inputs. At the end of or after the test, the test engineers must compare the input and output to check that whether the outputs are correct or not. Practically the actual output and the expected output may vary because the unit testing is the only method which helps you to write the better code.

The unit testing phase is also capable of finding the designing errors of the application. For example, if you press a button on the website and the button is not doing what it should do, then it is also the fault of the designer instead of the developer. Unit testing is the backbone of all the testing process. The test engineers can use unit testing to keep the safety of code and design when they are doing various changes in the same piece of code. This is the only testing process which concerned with the source code of the application because all the other types of testing processes focus on the functionality of the process instead of source code.

Unit testing is also considered better for preventing regressions. Regression is a state where bugs can occur repeatedly many times. There is some specific piece of code where it is hard to detect the bugs, but with the help of unit testing, you can easily get those bugs and also fix the problem as soon as possible. While performing the unit testing process, test engineers must know which approach they must use in the testing process like test driven or data-driven. Most of the time test-driven testing processes performs well as compared to data-driven. But it is advisable that the test engineer must focus on both the approaches if they have adequate time then they must use both of them.

Integration testing

Suggested by name integration testing is a process where all the modules of the application are integrated and tested in one go. Integration testing is similar to unit testing, but there is a huge difference between them and the difference is that in unit testing every single module of the application was checked independently, but in integration testing, all the models must put together and tested as one application. The purpose of integration testing is to check how different models behave when they have to work with other modules. For integration testing, real databases are used to test the various aspects of the application. Integration testing focus on the situations where the unit testing could not perform well. Sometimes you need to test to verify that it if a database and application are working together correctly or not. As a result integration testing also validate the results of the database with the expected results. Integration testing also checks various queries of the database to ensure that the database is working fine.

Functional testing

The purpose of functional testing is to check the complete functionality of the application. In functional testing all types of applications like web applications, desktop applications and mobile applications architect as per the functionality and compatibility of the application with different devices and atmosphere. As we know today there are lots of devices, browsers and also various operating systems available. It is important for the test engineers and organisation to make sure that all the components of the application work fine with all the types of browsers and other platforms. While unit testing and integration testing focus on the source code of the application, functional testing focus on the result of the source code. The functional testing uses client requirement specification as input. In functional testing, the output is compared with the expected output to make sure that all those functions of the applications are working fine. Functional test with automation tools is very much in trend these days.


All three types of testing processes have their significance. The unit test focuses on the small good use of the application and on the other hand, integration testing focus on the complete application. It is very important to check every module independently as well as dependently to make sure that in both conditions, how differently module react? Functional testing of the application has no concern with the code of the testing it is only concerned with the functionality of the application.

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