Head-To-Head: Integration Testing vs System Testing

Testing your software applications at various stages of the software development life cycle (SDLC) is the best software development practice. Two critical tests that your software must pass are system testing and integration testing. Both tests are essential to every stage of the software development process, so every tester needs to be familiar with them.

Integration testing is a software testing type where independent units are integrated and tested for correctness. On the other hand, system testing is a testing level where tests are performed on a whole system to check functional and non-functional requirements.

So in this article, you will learn about integration and system testing and their differences. Firstly, let’s start with the integration testing.

What is integration testing?

It is a best practice when developing software to create different modules so you can easily comprehend the function of each unit. Then, later, integrate these parts to make a single parent module. Before you carry out a system test, you want to ascertain whether any impediments or miscommunications are causing these components to malfunction.

Integration tests will tell the developer how the modules or units interact to give the desired result. This test, which focuses on particular units or components, comes after unit testing. However, integration testing, which involves running tests on both modules and components simultaneously, aims to demonstrate how various modules interact.

Integration tests check for anomalies missed during unit testing and are performed before the system testing and after the unit testing. 

Developers, test engineers, and QA testers can all perform integration testing.

Types of integration testing

Different types of integration testing can be performed, depending on the needs of the software development project.

Here are some of the most common types of integration testing.

integration testing types

Integration testing can be performed in two different ways:

  • Incremental integration testing – Gradually integrate and test small groups of related modules or components until the entire software has been integrated and tested.
  • Big bang integration testing – All the modules or components of the software are integrated and tested as a whole. This non-incremental approach can save time and effort compared to other types of integration testing.

Furthermore, you can split incremental integration test type into the following approaches:

  • Top-down approach The higher-level modules of the software are tested first, with lower-level modules being integrated and tested later.
  • Bottom-up approachIn contrast with top-down testing, the lower-level modules or components are tested first.
  • Hybrid approachThis approach combines top-down and bottom-up integration testing, allowing developers to simultaneously identify and resolve issues in both the higher-level and lower-level components.

Advantages of integration testing

Integration testing has several advantages to consider when planning a software development project.

  • Early detection of issues: Identifies issues and defects that may arise when different software components are integrated, allowing developers to address them beforehand. Those issues can’t be caught with unit testing.
  • Improved software quality: It improves software quality by ensuring different components work seamlessly together. Also, you can run the integration test suite repeatedly as part of the CI/CD process. 
  • Meeting the requirements: Provides a comprehensive view of the software, ensuring it meets end-user requirements.
  • Reduced risk of failures: Helps reduce the risk of software failures by identifying and resolving issues before they impact end-users or other modules of the software.

Disadvantages of integration testing

Here are some of the most common disadvantages of integration testing.

  • Complex and time-consuming: Complex and time-consuming processes, especially for large and complex software.
  • Difficult to isolate errors: Difficult to isolate and diagnose the errors, as they may involve multiple components or modules of the software, hence making it challenging to identify the root causes.
  • Limited test coverage: May not provide complete test coverage of the software, as it may not test all possible scenarios and combinations of components.
  • Costly to Implement: Costly to implement, as it may require specialized testing tools, additional resources, and infrastructure to execute tests and analyze results.

What is system testing?

When all the different units have proven to function as a single entity, thanks to integration tests, they become a system. A system test evaluates the system’s overall performance. A type of software testing called system testing evaluates the overall performance and functionality of a fully integrated, all-inclusive software solution.

Here, the tester aims to ascertain whether the program achieves its design intent and meets user requirements. Additionally, it retrieves errors and flaws preventing the system from operating as envisioned. Due to its extensive coverage and the advanced development stage of software testing, it meets the criteria for being an end-to-end test.

Techniques and approaches to system testing 

Consider requirements-based and use-case-based approaches when selecting a system testing method and strategy.

  • Requirements-based: This method involves creating tests using the project documentation or the specifications. 
  • Use Case-based: This method involves running tests that closely mimic user behavior and validating scripts to identify the system uses.

Below are a few examples of the many different types of system tests. 

  • Functional testing: System testing of this kind concentrates on software features and examines each functional aspect to ensure that it satisfies the requirements. 
  • Performance testing: This type of system testing looks at how the software behaves in various settings and circumstances. It estimates system response, speed, and stability.
  • Graphic user interface (GUI) testing: The entire visual user interface, which customers use to interact with the software, is put to the test. With this integration test type, you can test components like input fields, text rows, buttons, etc. 
  • Usability testing: This type of testing enables you to evaluate the program’s overall usability while considering logical and emotional factors.
  • Compatibility testing: You can use a compatibility test if the software supports different platforms and browsers.
  • Compliance testing: Developers use compliance tests to verify that the program meets all legal requirements.
  • Security testing: this is the way to make sure the app is safe to use and well-protected from hackers and scammers.

Advantages and disadvantages of system testing

The following are the advantages of system testing:

  • The entire software is put through a system test to look for flaws.
  • Examine the software from the user’s point of view and conduct experiments using real-world scenarios.
  • Tests for both functional and non-functional testing are included as a test for performance, usability, regression, and other factors.
  • While using various test scripts to ensure the system’s full functionality, it also attends to the client’s technical and business needs.

However, the system testing also has some drawbacks:

  • The entire application needs to be tested, which takes time. The cost may also rise depending on the business requirements and application architecture.
  • System test requires careful planning, coordination, and execution because they can be challenging and complex, especially for large and complex systems.
  • This test is susceptible to external influences from hardware and network configurations.

System testing vs. integration testing

It should be clear from the above description of system and integration tests what these tests are and why you need them when developing software. The differences between these two kinds of software testing are detailed below.

  • While system testing examines the entire system, integration testing focuses primarily on one or a small number of integrated modules.
  • System testing verifies that the whole system adheres to the requirements and design specifications. Integration testing guarantees each component’s functional behavior is correct. 
  • Before conducting a system test on an application, one of the numerous testing techniques is integration testing. This means that you perform an integration test before the system test.
  • Both the system’s functional and non-functional aspects are covered by system testing. Integration testing only performs functional testing on integrated and related components, though.
  • Black-box techniques are sufficient for software application system testing, whereas  integration testing employs both white-box and black-box techniques (also known as gray-box software testing technique).

When to use integration testing vs. system testing

After conducting unit tests, the next step is to carry out integration tests. Integration testing is a type of test that can be run continuously while the software is under development since it checks how different components interact. When the software development is nearing completion, you will require systems testing.

How integration testing and system testing complement each other

You can imagine the number of errors you will encounter during system testing if you omit integration testing. This implies that integration testing helps to improve how different components respond, which helps to ease the job of system testing.

System testing only needs to use the black box testing technique because of the effort of integration tests.

Examples of when to use integration testing and system testing

Let’s say you are creating a crypto-betting application. The algorithm requires that the user login after registering with certain credentials to access the site’s services. The login and sign-up are separate units, even though they seem to depend on each other.

You have other components, like the different games bettors can bet on, available bonuses, and live game bets. 

The registration and login modules’ interaction with the database makes this possible, and any error during this process means the user cannot bet. An integration test might be required to test how the login and registration components interact and how the data are stored and fetched from the database. 

If the flow appears to be different, there is an error. You must run integration tests to identify and correct this bug. After confirming that other components are functioning, system testing checks the functional and non-functional aspects of the software. This includes tests for performance, compliance, security, display, and so on.

Integration testing vs. system testing: table of comparison

Integration testing System testing 
This type of test follows unit testing.This type of test follows integration testing.
The tester must understand the internal structure, the project objective, and the programming language. Notably, the tester must be among the team that designed the algorithm for the software.System testing can be run by a team separate from the development team.

The features that make up the system interface between various modules are crucial here.The behavior of the module or units as a whole is what matters.
Only the functional components are tested at this stage.Here, testers must test the functional and non-functional elements of the software.
Integration testing employs black-box and white-box software testing techniques.Software testing techniques in system testing include just the white box testing


The main distinctions between system and integration testing are in how, when, and why you need each type of software test. But keep in mind that both tests improve the quality and performance of the software.

System testing tells a developer how the application conforms to functional and non-functional requirements. In contrast, integration testing involves testing the interaction between the modules or units of the software under development.

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