Understanding the Different Levels of Testing in Software Development

In software testing, there are four levels of testing: Unit testing, Integration testing, System testing, and Acceptance testing.

These four levels of testing must be completed before the software is released, as these testing levels add value to the software development life cycle (SDLC). Each of these levels of testing serves a specific purpose and can be performed in-house by developers or outsourced to professional software testers.

You can also explore these articles:

Let’s explore different levels of testing in software development in detail without any further delay. But before that, let’s quickly explore the list of topics listed under the table of contents (TOC) that we will cover in this article.

Table of Contents (TOC)

• What do you Understand by the Term “Testing Levels” or “Levels of Testing”?
• Different Levels of Testing in Software Testing
  • Unit Testing
  • Integration Testing
  • System Testing
  • Acceptance Testing
• Conclusion

What do you Understand by the Term “Testing Levels” or “Levels of Testing”?

Testing levels, also known as Levels of Testing, are a procedure for locating defective areas while preventing errors in development life cycle stages. This procedure or these levels of testing assist developers in maintaining software quality while ensuring that the software is free of defects or bugs.

You can also explore these articles:

Different Levels of Testing in Software Testing

As stated above in the article, there are four levels of testing in software testing: unit testing, integration testing, system testing, and acceptance testing.

Here’s a graphical representation:

Let’s explore each of these levels of testing in detail, along with their primary objective, advantages, and disadvantages. 

Unit Testing

Unit testing is the first level of testing. This testing is the most basic type of testing done by the developers before handing the software/product to the testing team.

Unit Testing Definition: Unit testing is a type of software testing in which individual units or components of the software are tested.

Primary Objective: The main objective of unit testing is to isolate each component of the software and then perform tests to illustrate that every individual component is accurately meeting the requirements and delivering the expected output.

Also explore: Software Engineer Online Courses & Certifications

Advantages of Unit Testing

Here are some of the advantages of unit testing:

• Helps to catch bugs/defects earlier, which preserves both – time and money
• Detects regression bugs (It is a kind of bug that is not found until and unless the software/product is released or is in production)
• Helps to understand the behavior of the code 
• The cost of conducting unit testing is low.

Disadvantages of Unit Testing

Here are some of the disadvantages of unit testing, such as:

• Writing test cases takes time.
• Unit testing is incapable of detecting all errors.
• GUI code testing must be performed correctly, as it will be challenging to test the software’s graphical user interface using unit testing. 

Integration Testing

Integration testing is the second level of testing. The testers, rather than the developers, mainly conduct this testing. This testing can be performed manually or using integration testing tools, such as Selenium.

Integration Testing Definition: Integration testing is a type of software testing in which individual software components (modules) are logically integrated (combined) and tested as a group.

Primary Objective: The main objective of integration testing is to verify whether individual modules, when combined (integrated), work correctly or not as a group.

Also explore: Free Software Engineer Courses Online

Advantages of Integration Testing

Here are some of the advantages of integration testing:

• Increases test coverage
• Offers a higher level of reliability
• Aids in the identification of integration issues between modules
• Helps to ensure that the integrated components (modules) work properly before proceeding to the next level of testing: system testing
• Bugs discovered at this level are more uncomplicated to resolve than those discovered at later levels of testing.

Disadvantages of Integration Testing

Here are some of the disadvantages of integration testing, such as:

• It can be challenging to perform in comparison to system testing.
• Testing the integration between the various connected modules takes a long time and a lot of resources.
• It necessitates the creation of stubs and drivers, which, if not done correctly, can result in insufficient testing.
• Lower-level modules need to be adequately tested.
• The test output is difficult to observe.

System Testing

System testing is the third level of testing. This level of testing assists you in identifying bugs and challenges while ensuring that the software will meet all specific requirements. A specialized testing team is usually in charge of this type of testing.

System Testing Definition: System testing is software testing in which all components are tested together (as a whole) to ensure that the final product meets the specified requirements.

Primary Objective: The main objective of this level of testing is to make sure that the software/product meets specified requirements and runs as smoothly as possible in its operating environment. 

Advantages of System Testing

Here are some of the advantages of system testing:

• Covers complete end-to-end software testing.
• Tests both: the system software architecture and business requirements 
• Assists in resolving post-production issues and bugs

Disadvantages of System Testing

Here are some of the disadvantages of system testing, such as:

• Requires a lot of time as it needs to test the entire framework
• Increases the testing cost and the effort involved, as business requirements and software architecture must be considered when conducting tests.

Acceptance Testing

Acceptance testing is the last and final level of testing. This level of testing is broad in scope, ranging from simply finding spelling and cosmetic errors to discovering bugs that might produce a significant error in the software.

Acceptance Testing Definition: Acceptance testing is a type of software testing that determines whether or not the software should be released to the public.

Primary Objective: The main objective of acceptance testing is to evaluate whether the software complies with the end-user requirements and whether it is ready for deployment.

Advantages of Acceptance Testing

Here are some of the advantages of acceptance testing:

• Identifies problems with new products before they reach users
• Allows the clients to test the features of the software 
• Increases satisfaction and reliability as client checks the software themself.
• Helps the client to understand the target audience in a better way after analyzing the data gathered using acceptance testing

Disadvantages of Acceptance Testing

Here are some of the disadvantages of acceptance testing, such as:

• Significant resources and planning are required.
• You have no say in which test cases are used.
• It is challenging to assess test progress.

You can also explore these articles:

Conclusion

In software testing, there are four levels of testing, such as:

• Unit testing: This is the first level of testing that determines whether or not software components fulfill functionalities.
• Integration testing: This is the second level of testing that verifies data flow from one module to another.
• System testing: This is the third level of testing that examines both functional and non-functional testing requirements.
• Acceptance Testing: This is the fourth level of testing that verifies that the requirements have been met.

Also read: What Does A Software Engineer Do? Roles, Responsibilities, and Skills

Early detection of software errors is critical because it takes more effort to fix bugs at the ending phases, near the launch, rather than correcting them at the beginning of software development. As a result, testing early and frequently is very important.