Software Testing - Stub

There are multiple elements which need to be taken into consideration to develop a software which is seamless to use, and ensures a high quality. The drivers, and stubs play a major role at the time of testing. They are used as alternatives to the modules that are not yet ready from the development perspective. Thus with the help of the drivers and stubs testing can be kicked off even when the development of the software is still in progress.

The drivers and stubs are used for the components which are yet to be developed, missed, or in progress with respect to the development. As a result, both the drivers, and the stubs serve as a replacement for the original components of the software. They are capable of simulating the features, and functionalities of the missing components. They are very helpful in minimizing the delays in the testing cycles, quicken the overall testing process, and increase test efficiency.

What are Software Stubs?

The software stubs are used in the top down integration testing. They are implemented by the developers as alternatives to specific units of the software which are missed or have not been developed completely. They have the capability to simulate all the features of the unavailable modules of the software. They are mainly used when certain lower level components are required for testing but inaccessible at that moment.

The software stubs should be developed such that they show the traced and displayed messages. They also process the values which the actual modules are supposed to act upon. Moreover, they obtain the parameters or arguments that are to be used at the time of testing.

Stubs are also used when the software needs to interact with an external system.

Stub Flow Diagram

The above diagram clearly states that Modules 1, 2 and 3 are available for integration, whereas, below modules are still under development that cannot be integrated at this point of time. Hence, Stubs are used to test the modules. The order of Integration will be −

1,2
1,3
2,Stub 1
2,Stub 2
3,Stub 3
3,Stub 4

Testing Approach

+ Firstly, the integration between the modules 1,2 and 3
+ Test the integration between the module 2 and stub 1,stub 2
+ Test the integration between the module 3 and stub 3,stub 4

What are Software Drivers?

The software drivers are used in the bottom up integration testing. They are created for the same purpose as stubs, however they are much more complicated than the stubs. They are used when some of the modules are still undeveloped for some reasons at the time of testing. Thus the drivers act as a replacement for those missing modules. They are mainly used when certain higher level components are required for testing but inaccessible at that moment. Also, the drivers, and stubs can be used simultaneously at the time of testing.

Let us take an example of an e-commerce having the components namely login, product search, payment, order summary, and help. It is always recommended to begin testing parallely for all the components so that the moment one of them is developed, they can be combined with the others and verified. However, it is normally seen that the components are not fully developed to be used for testing. In such a scenario, the drivers, and stubs are used.

Let us take a situation in which the login module is ready, however the product search module development is still in progress. At this time, drivers or stubs can be used to simulate the working of the product search module. Thus they help to go ahead with the testing if certain modules are still not available. In the same way, the drivers and the stubs can be used if the other modules such as payment, order summary, and help have not been completed from the development perspective.

Do the Driver and Stub Perform the Same Functionality?

Yes, both the driver and the stub perform the same functionality and can be used at the time of testing due to unavailability of one module which has dependencies on another module.

Differences between a Stub and a Driver

Conclusion

This concludes our comprehensive take on the tutorial on Software Stub. Weve started with describing what are software stubs, what are software drivers, do the driver and stub perform the same functionality, and what are the differences between a stub and a driver. This equips you with in-depth knowledge of Software Stub. It is wise to keep practicing what youve learned and exploring others relevant to Software Testing to deepen your understanding and expand your horizons.