i. Integration is process by which components are aggregated to create larger components.

ii. Testing the data flow or interface between two features is known as integration testing.

iii. It mainly focuses on I/O protocols, parameters passing between different unit‘s modules and/or system etc.

Types of Integration testing:

1. Top-down Testing:

In this approach testing is conducted from main module to sub module. If the sub module is not developed a temporary program called STUB is used for simulate the sub module.

Advantages:

• Advantageous if major flaws occur toward the top of the program.

• Once the I/O functions are added, representation of test cases is easier.

• Early skeletal Program allows demonstrations and boosts morale.

Disadvantages:

• Stub modules must be produced

• Stub Modules are often more complicated than they first appear to be.

• Before the I/O functions are added, representation of test cases in stubs can be difficult.

• Test conditions may be impossible, or very difficult, to create.

• Observation of test output is more difficult.

• Allows one to think that design and testing can be overlapped.

• Induces one to defer completion of the testing of certain modules.

2. Bottom-up testing:

In this approach testing is conducted from sub module to main module, if the main module is not developed a temporary program called DRIVERS is used to simulate the main module.

Advantages:

• Advantageous if major flaws occur toward the bottom of the program.

• Test conditions are easier to create.

• Observation of test results is easier.

• Driver Modules must be produced.

• The program as an entity does not exist until the last module is added.