Integration Testing

Definition: Integration testing is the phase in software testing in which individual software modules are combined and tested as a group.

• Interaction between two or more “units” is explicitly tested.
• Integration tests verify that the components of your application work together.
• It occurs after unit testing and before validation testing.

 Type of Integration Testing

Bottom Up Testing: In this approach of integration testing  the lowest level components are tested first, then used to facilitate the testing of higher level components. The process is repeated until the component at the top of the hierarchy is tested. In this approach testing is done from the bottom of hierarchy with the help of “Drivers” (Temporary programs).

 

 

Top Down Testing: In this approach of integration testing  the top integrated modules are tested and the branch of the module is tested step by step until the end of the related module. In this approach testing is done from the top hierarchy with the help of “Stubs” (Temporary programs).

 

 

 Sandwich Model: In this approach testing is done from both ends using “Stubs” and “Drivers”.

 

 

 

Difference between Stub & Driver

Stub	Driver
Temporary Program is used instead of Sub-Programs, which are under construction	Temporary Program used instead of main program, which is under construction
Used in Top – Down approach	Used in Bottom – Up approach
Other name is “Called Programs”	Other name is “Calling programs”
Returns Control to the main program.