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Integration Testing & Types

By Rakesh Raj • January 11, 2024

What is Integration Testing?

Integration testing plays a pivotal role in software development, ensuring that individual software components come together to form a coherent and functional system. This testing process concentrates on verifying the interactions between software modules to ascertain their proper collaboration. It is a critical step in the software development lifecycle as it aids in detecting and resolving errors that may emerge when multiple components are combined into a single system.

Integration testing is the process in which the interface of different applications, modules, or components of a software application is tested as a combined group. Integration testing is the second level of the software testing process. And takes place right after unit testing and just before system testing. Simply put, integration testing shows the testing team how well disparate elements work together.

Conflicts between software modules can arise from various factors, including differences in subsystem versions, data format disparities, or conflicting processing logic. Integration testing serves the purpose of identifying communication issues between software components and typically occurs after unit testing but before system testing.

Integration testing involves logically integrating software modules and subjecting them to testing as a unified group. In a typical software project, multiple modules are coded by different programmers, and the primary objective of this testing level is to unveil defects in the interaction between these integrated software modules, with a particular focus on assessing data communication among them. This form of testing is also called ‘I & T’ (Integration and Testing), ‘String Testing,’ and sometimes ‘Thread Testing.’

Types of Integration Testing

There are several strategies to perform integration testing, each of which has its advantages and disadvantages, with the 2 most common approaches being:

  • Big Bang Approach
  • Incremental Approach

Incremental Approach is carried out by 4 different methods:

  • Bottom-up approach
  • Top-down approach
  • Sandwich approach
  • Hybrid Integration Testing

Big Bang Approach

This strategy involves combining all the modules and testing the software system in its entirety. While it’s an uncomplicated method, debugging can be complex if something goes wrong.

Incremental Integration Testing

Incremental integration testing is an effective way to detect problems early in development. This testing strategy involves integrating modules one by one. You then verify that each module performs as expected until all components have been tested as a complete system.

Bottom-Up Integration Testing

We begin with the most critical lower-level modules and progress to higher-level ones. This is the exact opposite of top-down testing — making it perfect for those projects where the bottom components are more important than the top.

Top-Down Integration Testing

Methodically, the higher-level modules are evaluated first. Detailed evaluations of the lower levels follow. This enables you to prioritize and focus on those components deemed most critical.

Sandwich Integration Testing

This strategy offers a comprehensive approach to testing. Sandwich integration testing begins with assessing the higher-level modules. You then move on to examining the lower-level components and eventually work back up.

Hybrid Integration Testing

This is the perfect solution for software applications of all sizes. Hybrid integration testing offers a tailored approach by combining various integration testing techniques.

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