What are different types of integration testing?

Most of us are familiar with the concept of the integration testing but, still let use brief up ourselves before we move on to the types of the integration testing. Integration testing is nothing but to integrate first and then test. It is often abbreviated to I&T. There are 3 primary phases in any software testing process:


1. 1st phase: Unit testing
2. 2nd phase: Integration testing
3. 3rd phase: Validation testing

About Integration Testing

- Integration testing is carried out after the completion of 1st phase i.e., unit testing.

- Integration testing involves the integration of the various software modules together and then subjecting them to testing.

- Each of the modules integrated in a group during the integration have passed the unit testing successfully.

- The modules which don’t pass the unit testing cannot be further processed for the integration testing.

- After the modules pass even the integration testing, they are carried forward for the system testing and later to system integration testing.

- The integration testing aims at the verification of the features, functionalities, reliability, performance and requirements specified for the assemblages or design items of that particular software system or application that is currently under the test.

- The exercising of these assemblages is done with the help of the black box testing techniques.

- Any error or bug occurring during the integration process is simulated using the proper input data values or parameters.

- Apart from testing just the integration of the software modules, the inter- process communication and the sub systems are also tested via their interface.

- Special test cases are designed to carry out the integration testing.

- The integration testing follows the approach of the “building block”.

Different Types of Integration Testing

Now let us see what all are the different types of integration testing.

1. Non incremental integration testing or Big bang integration testing

- This approach to integration testing involves the coupling of the individual developed modules so as to form a proper and complete component of a software system or application.

- After this the integrated component is subjected to the integration testing.

- Among all the types of integration testing, the big bang integration testing methodology proves to be the most effective methodology for saving one’s precious time.

- But, the condition here is that the test cases must be well developed without any errors and their outcomes must be recorded without any mistakes.

- If any discrepancy or error leaks in the results of the test cases, then the whole integration process can turn out to be more complex rather than becoming easy.

- This in turn will act as a hindrance in the way of achieving the goals.

- Big bang type integration testing has got another type called “usage model testing”. This has an added advantage that it can be used for the hardware also rather than juts for software integration testing.

2. Incremental Integration Testing

This type is further divided in to three sub- types:

(a) Bottom up integration testing

- This approach involves the testing of the components at the lowest levels first and then succeeding to the higher level components.
- This process continues till the all the higher level components have been tested.
- This approach is effective when it comes to rooting out the bugs.

(b) Top down Integration Testing

- This approach involves the testing of the integrated modules at the top of the hierarchy model and then the lower level components are tested.
- This approach is effective when it comings to find a missing branch.

(c) Sandwich Integration Testing
- This approach is the resultant of the combination of both the top down and bottom approaches of the integration testing.