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Best Approaches of Integration Testing

woodjessica profile image Jessica Wood ・3 min read

Enterprises are effectively in need of quality software and to achieve them, teams rigorously perform software testing before releasing it for their end-users. Software testing involves four important software testing levels, from which integration testing is one of the testing practice that is performed after the first software testing phase. With this testing practice, it is easier for the teams to validate the correctness and performance of the smaller components after integration. Thus, it is a very important testing practice for achieving quality software. However, to make this process more efficient, teams should hold complete knowledge related integration testing approaches, benefits, etc.

Integration testing is one of the important software testing types in the software development lifecycle (SDLC). It is practiced after unit testing, i.e. the first testing phase. In unit testing, the software is broken into smaller modules or components and these are individually tested in isolation. These individually tested modules are combined in the integration testing practice to test the performance and behavior.

Why Integration testing is important for enterprises?

Many enterprises effectively employ integration test engineers in order to identify the bugs or defects that can be existed even after unit testing. Also, this way of identifying the bugs in the modules in the early stage enhanced the quality of the software. There are several benefits that can be achieved with integration testing such as:

Helps in assuring that the integrated modules work properly as needed
Assures that the modules are able to interact with the APIs and other third-party tools
Helps in identifying the bugs or defects that can be present in between the interface and modules
Enhances the test coverage
Increases the reliability of the tests, etc.

What are the different integration testing approaches?

In the Integration Testing approach, there are four important integration testing approaches:

Top-Down Integration Testing Approach: In this testing approach, testing is started by testing the top-most modules and then moving down gradually to test the lower modules one after the other. Also, in this method, testing is taken place from top to bottom.
Advantages with Top-down testing approach:
It helps in debugging the modules separately
In this method, there may or may not be need of drivers
It is more accurate and stable
Bottom-up Integration Testing Approach: In this integration testing type, each and every module at the lower level is tested with higher modules. The bottom-up integration testing approach makes use of drivers to drive and share the appropriate data to lower module levels.

Advantages with Bottom-up Testing Approach:
In this method, there is no need for any stubs
With this testing approach, a number of disjoint sub-systems can be tested at the same time
Big-Bang Integration Testing Approach: In this testing approach, the modules are first developed and then tested individually to validate the functionality. The only advantage of this integration testing practice is that it is well-suited for small systems.
Sandwich Integration Testing Approach: This testing approach is also known as hybrid integration testing and mixed integration testing. It is widely known as the combination of both top-down and bottom-up approaches. In this testing approach, the system is viewed in three layers, i.e. the main target layer, the layer above the target layer, and the last one below the target layer.
Advantages with Sandwich Integration Testing:
In this method, both top-down and bottom-up approaches can be performed simultaneously
It is well-suited for large enterprises and big projects


In order to achieve quality and error-free software, it is important to validate the functionality and correctness of each module from the initial stage of software testing.

Integration testing is one of the important testing phases that helps in assuring this requirement. With integration testing, teams can effectively validate the functionality of the individually tested modules after integration.

Thus, to validate the functionality of modules after integration, this testing practice has huge importance. Leverage integration testing services from independent QA testing services provider for identifying the errors between the interface and the modules.

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