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Unit Testing for Application Softwares.

Unit Testing for Application Softwares.

31 August 2022 4 MIN READ BY Rajesh K
  • What is Unit Testing?
  • Advantages of Unit Testing
  • Unit Testing Process
  • Unit Testing Methods
  • Unit Testing Techniques

What is Unit Testing?

A unit may be an individual function, method, procedure, or a module and is the smallest piece of code that can be logically isolated in a system. Units are the smallest testable parts of an application software.

  • Units are separately explored for identifying issues in Unit Testing. Its primary purpose is to validate each unit independently against its purpose or performance.
  • Unit testing is done during the development process of an application software by the software developers and sometimes QA staff.

Advantages of Unit Testing

The main advantages are,

  • Unit testing helps software developers/software testers in getting familiarized with the functionality provided by a unit and on how to use the unit. It also helps them to acquire a basic understanding of the unit API.
  • Unit testing allows the software developer to manipulate the code to ensure the proper functioning of a module. This improves code quality.
  • Unit testing enables testing parts of the project without waiting for the completion of the whole project.
  • Defects are captured and rectified in the very early phase of the project thus saving much testing time late.

Unit Testing Process

The unit testing steps can be briefed as follows.

  • Create test cases: – Identify a unit test corresponding to the relevant feature to be tested. A section of code is written by the software developer in the application to facilitate this unit test. This section of code would later be commented out and finally be removed when the application is deployed.
  • Reviewing test cases: – The section of code to be tested is isolated to a separate testing environment. This helps in exposing unwanted dependencies between the code being tested and other units. These dependencies can then be removed.
  • Baselining test cases: – Software developers make use of Unit test frameworks or unit testing tools for handling automated test cases.
  • Executing test cases: – During the execution of test cases corresponding to unit testing, the unit testing framework helps to mark the test cases that fail and also helps in reporting those failed test cases. The unit testing framework further helps to stop the related testing in case of failures.

Unit Testing Methods

Unit testing can be performed in 2 ways.
  • Manual Testing: – The software tester manually executes each step of a test case and does not require to know about any testing automation tool. Manual Testing is tedious especially for tests that are repetitive and have many steps.
    “100% of Automation is not always possible and so there is always room left for some level of manual testing to be done.”
  • Automated Testing: – The test cases to be executed are automated and stored with the help of software testing automation tools. The automation tool can record and save the steps entered in test cases and they can be replayed as many times as required.
    “The automation tool can even compare the expected results to the actual results and automatically generate the reports.”

Unit Testing Techniques

Software testers utilize three types of unit testing techniques while testing each unit separately.

  • White Box Testing: – This testing requires an in-depth knowledge of the internal code structure of the program to be tested in order to ensure if it’s performing its intended function and to examine how it performs this.
    “Unit testing is a type of white box testing where the software developer inspects the lines of code to be tested to point out bugs in the earlier phase of the development process.”
  • Black Box Testing: – In this type of testing, software developers test the functionalities of an application software without possessing any knowledge about its internal code structure. The aim is to ensure that the functionalities are carried out accurately and efficiently. These tests are derived from the software specification document.
  • Grey Box Testing: – The grey box testing is a combination of black box and white box testing techniques. The testers possess only limited knowledge about the internal code structure of the application software to be tested. This type of testing is designed to identify bugs that result due to improper code structure or incorrect code.


Unit testing helps in ensuring the efficiency regarding the performance of all the individual units of the application software to be tested in its developmental phase itself. Detecting bugs and rectifying them during unit testing saves time and money rather than the testing done at the later stage of software development. Automation of test cases corresponding to unit testing is a good idea and can be done by software testing tools. A software testing framework can be used to develop and maintain these test cases.