Integration Testing & It’s Types

The practice of evaluating the interface between two software modules or units is known as integration testing. Its main goal is to ascertain whether the interface is correct. Integration testing is done to find errors in how integrated units interact with one another. Integration testing is carried out following unit testing of every module.

Software testing methods such as integration testing are designed to confirm how various modules or components of an application interact and share data. Finding any issues or bugs that develop when various components are merged and interact with one another is the aim of integration testing. Unit testing comes first, and system testing comes second regarding integration testing. Early detection and resolution of integration difficulties lowers the likelihood of more serious and expensive issues later in the development cycle.

One way to test integration is to select modules one by one. This can be done in order to establish a correct order that needs to be followed. Also, you must follow the right order if you wish to avoid missing any integration scenarios. The main goal of integration testing and the period of interaction between the integrated parts is to expose the faults.

Types of Integration Testing:

There are various methods for carrying out integration testing, and each has pros and cons. The two most popular methods are as follows:

• Big Bang Approach
• Incremental Approach

Incremental Approach is carried out by 3 different methods:

• Bottom-up approach
• Top-down approach
• Sandwich approach

 Big Bang Integration Testing :

This is the most straightforward method of integration testing; all the modules are merged, and functionality is confirmed once separate module testing is finished. Put another way, all of the system’s modules are just assembled and tested. This strategy works best for very small systems. It is quite difficult to localize an error that is discovered during integration testing because it could potentially be related to any of the interconnected modules. Therefore, it is quite costly to correct debugging flaws that were discovered during Big Bang integration testing.

Big-bang integration testing is a software testing methodology that involves combining and testing all of a software application’s modules or components at once. This method is usually applied when there is little interdependence between the program components or when the development environment has limitations that make it impossible to test individual components. Big-bang integration testing aims to confirm the system’s general operation and spot any integration issues that may develop when its components are put together. Big-bang integration testing is helpful in some circumstances, but it can also be a risky strategy because of the system’s complexity and the number of interactions between its many components, which can make it challenging to find and fix issues.

Pros:

• It works well with smaller systems.
• Basic and uncomplicated method.
• Able to be finished swiftly.
• Doesn’t call for a lot of organization or preparation.
• Might be appropriate for small-scale projects or systems where component interdependence is minimal.

Cons:

• Due to the need to wait for the integration of all the modules, there will be a significant delay.
• Since all modules are checked simultaneously, high-risk critical modules are not segregated and tested in a priority manner.
• Unsuitable for protracted projects.
• High probability of challenging to recognize and diagnose integration issues.
• Long and difficult debugging and troubleshooting procedures may follow from this.
• This may result in more expensive development as well as system outages.
• It might not give adequate insight into how different components interact and exchange data.
• This may cause people to lose faith in the stability and dependability of the system.
• Reduced productivity and efficiency may result from this.
• This could make people lose faith in the development team.

Bottom-Up Integration Testing :

In bottom-up testing, lower-level modules are tested with higher-level modules until all levels are tested. The main goal of this integration testing is to test the interfaces between the several modules that comprise each subsystem. Test drivers are used in integration testing to drive and transfer relevant data to modules at a lower level.

Pros:

• Under bottom-up testing, stubs are not necessary.
• One of the main benefits of this integration testing is the ability to test multiple disparate subsystems at once.
• Establishing the test conditions is simple.
• Ideal for applications that apply the bottom-up design methodology.
• Seeing the test results is simple.

Cons:

• It is necessary to develop driver modules.
• The testing demonstrates the complexity that arises from having a high number of little subsystems in a system.
• As of now, no functional model is possible to depict the Far modules that have been developed.

Top-Down Integration Testing :

Top-down integration testing is a technique that simulates the behavior of the unintegrated lower-level components. Testing is done from top to bottom in this integration test. To make sure the system is operating as intended, high-level modules are tested first, followed by low-level modules, and ultimately by merging the low-level modules to a high level.

Pros:

• Independently troubleshooted module.
• Drivers are either rare or not necessary.
• On the whole, it is more accurate and stable.
• Simpler interface error isolation.
• Early on in this, design flaws can be discovered.

Cons:

• Numerous Stubs are required.
• Lower-level modules are not thoroughly tested.
• It’s challenging to see the test results.
• Designing a counterfoil is hard.

Sandwich Integration Testing:

Another name for a sandwiched integration test is a mixed integration test. Top-down and bottom-up testing methodologies are used in a mixed integration test. Testing in a top-down method cannot begin until the top-level module has been coded and put through unit tests. Testing in a bottom-up approach cannot begin until the lower-level modules are completed. This flaw in the top-down and bottom-up techniques is fixed by the sandwich or mixed approach. Another name for it is hybrid integration testing. Moreover, drivers and stubs are employed in mixed integration testing.

Pros:

• For very large projects with numerous smaller initiatives, a mixed approach can be helpful.
• This flaw in the top-down and bottom-up approaches is fixed by the sandwich strategy.
• It is possible to run parallel tests for both the top and bottom layers.

Cons:

• Because one component of mixed integration testing uses a top-down method and another uses a bottom-up approach, it is quite expensive.
• Smaller systems with high levels of module interdependence cannot employ this integration testing.