The software applications driving the modern digital ecosystem, in conjunction with the hardware systems, are dependent on various third-party applications and platforms. The omnichannel footprint of software means each module (and the interface between modules) need to function smoothly to deliver the expected outcomes. This is ensured by conducting software integration testing.
One of the important characteristics of a software application is the seamless flow of information between its two ‘units’ or ‘modules’. However, the flow of information could be interrupted by the presence of glitches, which if not identified and corrected in time can make the application faulty. Thus, software integration testing helps to expose faults that lie at the interface between two integrated units. Once the individual units or modules are tested, the integration of interfaces gets validated.
To draw an analogy to this type of testing, let us consider two groups of friends who have been invited to a party. To find out if they can get along, they should be subjected to an ‘integration test.’ This is done by bringing them to a single room and observe how they interact. In a similar vein, to check if each unit of software functions seamlessly, they need to be integrated and tested. Thus, integration testing, as part of the software testing services, checks if all units function in harmony. It ensures if the modules developed by different developers are working towards a singular objective.
The various ways to test the integration of modules are as following:
Big Bang: As one of the most common ways to test the integration of software modules, the big bang involves smashing and testing all the units together. This may keep the tester in good stead if all the tests are completed or the software project is relatively small. However, it can have its cons as well. For example, in case a glitch is identified, it would be difficult for testers to figure out the right module or unit responsible for it. To find the erring module, testers have to detach a few of them and repeat the testing till they identify the glitch. Since this approach requires the modules to be ready before testing, it can extend the turnaround time for product release.
Incremental: Here, two or more logically aligned units are tested as part of a single batch. Thereafter, other similarly aligned units are checked eventually ensuring the interface of every single unit with another is validated. It combines both the bottom-up or top-down approaches.
Hybrid, Mixed, or Sandwich: This approach combines both bottom-up and top-down type of integration testing. Here, the top and lower modules are tested simultaneously for integration thereby deriving the best results. This approach can come in handy for large projects.
Since most software development processes are moving towards Agile or DevOps, it needs to be seen how integration testing can fit into a CI/CD environment. The software testing services for integration should have the following best practices.
Execute integration testing before unit testing: The waterfall model of software product testing has led us to believe that fixing a glitch later in the SDLC can be costly. This is due to the fact that one doesn’t move to the next stage until the completion of the present phase. This approach, however, can be turned on its head in an Agile environment. This is because Agile offers the flexibility to change the business logic in an SDLC.
Do not confuse unit testing with integration testing: Unit testing targets the basic code and needs to be run frequently to detect bugs. On the other hand, integration testing is much more time consuming and should not be part of every build cycle. However, it may be included in the daily build.
Extensive logging of processes: Identifying and mitigating bugs in a unit test are easy. However, given the scope and complexity of integration tests spanning a number of modules, doing the same is difficult. The need is to keep a record of processes to better analyze the reasons for failure.
Integration testing may be expensive and time-consuming but is essential to deliver quality products in the DevOps and Agile-driven environments.