Software Development

Unit Testing vs. Integration Testing: Key Characteristics and Benefits

Accurate testing of an application determines its performance, usability, and reliability. While testing is an integral part of the software development life cycle, there is no simple way to get it done in one go. Every software product goes through a series of testing by developers and a dedicated team of testers. These tests are carried out to determine how the application performs or behaves when exposed to different situations.

Amongst the series of tests, unit testing and integration testing are two of the most common types of tests that every software goes through. So let’s get to know more about the two types of tests, their distinctive characteristics, and how it helps maintain the smooth performance of any software product.

Unit Testing

The foundation of resilient software starts with developers conducting unit tests to determine the performance of their codes. As the name suggests, a unit test simply checks a single unit from the source code – a function or method call – within an application.

To give you a better perspective on unit testing, let’s imagine the source code of a complex application. While developers write code to create the intricacies within the application, they must also determine if their codes are functional, safe, highly performant enough for the product to work. Therefore, a unit test checks the smallest possible code in isolation from the entire source code.

While conducting a unit test can be easy, it is usually determined by how developers have structured their codes. Small, structured, and independent codes can be checked with ease. This allows them to fix bugs at an initial stage instead of making iterations at the very end.

Challenges in Unit Testing

Unit testing is one of the most common and most straightforward types of testing carried out by developers while they are writing the codes for components or functions. However, while it’s easy to perform a unit test on an application with the units and source code organized, it’s equally challenging to perform the same in an existing application. More so, when the codes are written without even considering the need for a unit test.

Benefits of Unit Testing

  • Individual codes tested in isolation give an accurate result of the code quality at the initial stage
  • Easy and quick testing methodology carried out by developers
  • Shorter execution time allows developers to conduct unit tests as many times as they want
  • Decreases technical debt and maintenance cost in the long run

Integration Testing

Unlike unit testing, which only focuses on the smallest code, integration testing checks the entire source code and its dependencies. No matter how accurate the smallest codes might be, the application would be useless if the entire source code didn’t function appropriately in an external environment after deployment. In other words, the test checks the application in its entirety.

Integration tests are often carried out by a dedicated team of testers who don’t have an idea of how particular codes work. They expose the application in different external situations to quality check its performance and functionality.

Given that integration tests check the entire application, its dependencies, and the area where software interacts with external systems, it’s not ideal to run it too many times. A lesser number of tests itself makes it highly impactful for quality assurance. While developers might feel that there’s a 100% coverage of source code, the integration test unearths the bugs that arise when the code interacts with one other.

Challenges in Integration Testing

While integration tests are created to check component interactions with the real world, it is not a child’s task to create a real-life environment. There would always be some limitations because external systems are difficult to integrate into test environments. Irrespective of the challenges, there are various solutions available for testers to make the integration test closer to real-world interactions.

Benefits of Integration Testing

  • Checks how the entire source code reacts to one another in a production environment
  • Identifies bugs from source codes as well as from external resources
  • High impact test that checks interfaces and interactions between different modules within an app
  • The use of actual dependencies to test the application makes it highly accurate

Which Test to Choose?

When it comes to software applications and their testing methodologies, every situation differs. While it might theoretically sound ideal to use different types of testing, choosing a specific type would always depend on client requirements and business goals.

Unit and integration testing can be considered types of testing that have to be conducted in a sequence. For example, developers can run unit testing while they are writing codes for new features. On the other hand, testers can run integration testing as a second test to check the functionality and performance of the entire app. While there are exceptions to every situation, the ideal situation for a software application is to be deployed once it is thoroughly tested.

Hardik Shah

Hardik Shah works as a Tech Consultant at Simform, a leading custom software development company. He leads large scale mobility programs that cover platforms, solutions, governance, standardization, and best practices. Connect with him to discuss the best practices of software methodologies @hsshah_.
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