Moreover, the main aim of software testing is to validate whether the end product meets the requirements of the client or not. During the process of development a software or application goes through several types of testing, which tests and examines different features, qualities and functionality of the software. Integration testing is a type of software testing, which is performed on software to determine the flow between two or more modules by combining them. Integration testing makes sure that the interactions between different components of the software is completed smoothly without any complication.
The term ‘integrate’ as defined by Cambridge Dictionary means, “To combine two or more things in order to become more effective”. This definition of the term integrate defines the basic purpose of integration testing, which is a software development process where program units are combined and tested as groups in multiple ways. In this context, a unit is defined as the smallest testable part of an application. In other words, Integration Testing is the phase in software testing, wherein individual software modules are combined and tested as a group. It occurs after unit testing and before validation testing.
Furthermore, when software application is tested through integration testing, it exposes the problems and issues with the interfaces among program components before trouble occurs in real world execution. This type of testing takes its input modules that have been unit tested, groups them in larger aggregates, applies tests defined in an integration test plan to those aggregates, and delivers as its output the integrated system ready for system testing. Moreover, integration testing is a component of extreme programming, which is a pragmatic method of software development that takes meticulous approach to build a product by means of continual testing and revision.
From testing codes in proper context to combining and testing the components or modules of the software, integration testing is immensely useful. It is a type of software testing that not only ensures the quality of the software, but also makes sure that the software is tested in the production like environment before it is released for the use of the end users and clients. Integration testing, which is also known as Integration and Testing (I&T), is performed through various types of approaches that are either executed by the integration tester or by a test team.
As stated before, in this type of software testing program units are combined and tested as groups in multiple ways, hence each and every type of integration testing carries a lot of significance as they help testers in determining the effectiveness as well as the functionality of the software. Moreover, the various types of integration testing can be categorised into two different groups that are mentioned below:
In Incremental integration testing, the developers integrate the modules one by one using stubs and drivers to uncover defects in the software program. Here, each module has a definitive role to play in the project or product structure and has clearly defined dependencies, which can be known only at the runtime. The most important quality of incremental integration testing is that the defects are found early in a smaller assembly, when it is relatively easy to detect the root cause of the same. Incremental Integration Testing is performed on software through the following approaches:
Whenever the relationship between the modules is not clear, non-incremental integration testing or big bang integration is executed. In this case the data is created in one module and is combined with all the other modules to check as well as test the flow of data between them. It is because of this that non-incremental integration testing is also known as Big Bang Integration.
Sandwich testing is a culmination of both incremental as well as non incremental integration testing, wherein Bottom-Up approach is focused on middle to top layer, Top-Down approach is concerned about layers from middle to downwards and the Big Bang approach is followed for the middle layer. This type of testing combines the advantages of all the three approaches and is mainly used to test large projects.
From the above discussion we can conclude that the importance of Integration testing and its types in extremely high during software development process. Integration testing, which is a type of software testing, combines and tests units in groups through various ways as well as testing types.
The main purpose of this level of testing is to expose faults and other discrepancies, which are found when interactions are happening between integrated units. Moreover, to achieve desired goals and to detect all the faults in the integrated units, the test drivers and test stubs are used in integration testing, which assist testers with the process of testing. Hence, if a tester wants to have a streamline development process, where getting new features into production is fast and easy, then they should implement integration testing.
In short, upon the completion of unit testing, the units or modules are integrated, which gives rise to integration testing, which aims at verifying the function, performance, and reliability between the modules that are integrated.