What is Integration testing ?

• Integration testing performed between 2 or more  modules.
• Integration testing focusses on checking data communication between multiple modules.
• Integration testing is a white-box testing technique. 
• Developers perform this test in coding level.
• Testers perform this test in UI level (User Interface).

Types of Integration Testing

1. Incremental Integration Testing

2. Non-Incremental Integration Testing

Incremental Integration Testing

Incrementally adding the modules and testing the data flow between the modules.

2 Approaches- Top down approach and Bottom up approach

Top down - Incremental Integration Testing:

Incrementally adding the modules and testing the data flow between the modules. And ensure the module added is the child of previous module. 

Bottom up - Incremental Integration Testing:

Incrementally adding the modules and testing the data flow between the modules. And ensure the module added is the parent of the previous module.

Sandwich/Hybrid approach:

combination of both top down and bottom up approach.

Non-Incremental Integration Testing

Adding all the modules in a single shot and test the data flow between modules.

Drawbacks

- we might miss data flow between some of the modules.

- If you find any defect we cant understand the root cause of the defect.