Integration Testing

Integration Testing is the type of software testing, which individual modules/components of software is combined and tested as a group; this is done once the individual modules/components are tested and validated. Integration Testing is done with intention to reveal the existence of issue/failure between the modules of software.

Integration Testing

Here before starting integration test, as a unit module 1, module 2 and module 3 tested individually. Once having successful validation on the individual modules, finally all the modules are combined and tested as a group which meant integration testing.

Methods of Integration Testing:

Two Types of approach in integration testing,

1.       Big Bang Approach

2.       Incremental Approach

a.        Top down Approach

b.       Bottom up Approach

Big Bang Approach:

In this approach, completed individual modules are not tested at initial, instead once all the modules are ready, and are integrated and tested at a once. Consider the above picture, without testing individually module 1, module 2 and module 3, all the modules are combined and tested at a once. 

Incremental Approach:

In this approach, once the individual modules are unit tested successfully, and further testing is carried on by integrating two or more modules, this will continue till all the modules are combined and tested successfully. Consider the below picture once module 1 and module 2 is ready, those are integrated and tested successfully. 

Incremental Approach

Bottom up Approach:

In this approach, test starts from the lowest module and finally with the higher modules.This testing will continue till all the modules are integrated and test completed from lowest to highest modules.

In this scenario module 3 and module 4 are lowest modules that are developed and test completed. But still the higher module 1 & 2 not yet developed, since the higher modules having the function’s to call the lower modules, so in this place ‘Drivers’ are used as dummy program of module 1 & 2 to integrate with module 3 & 4. This approach helps to detect the failure at early stage in the lowest modules.

Bottom up Approach

Top down Approach:

In this approach, unit test starts from the highest module and finally with the lower modules. This testing will continue till all the modules are integrated and test completed from top to lowest modules.  Assume here top is module 1, and it’s developed and unit tested and still module 2 is not yet developed it is in progress. In order to test module 1 with 2, ‘Stubs’ is used in the place of module 2. ‘Stubs’ is dummy program which acts as lowest module to integrate with highest modules.

Top Down Approach