Why integration testing?

In real-world software development, each application development is divided into a number of small modules. These modules will be developed by different developers. It's very important to find out how such separately developed modules when combined together are working. Each application is developed in different layers, such as UI, business layer, and DAO layer. In each layer, the data which is accepted, processed, and passed may be in a different format. So it's very important to find out whether the data passed and collected is correct or not, otherwise there will be a manipulation problem. Integration testing is also important as developers face a big problem in meeting continuous changes in requirement. Integration testing helps to find out problems of collaboration on layers at an early stage instead of getting it in later stages of development.

Let's implement this in our application to test form validation:

1. Create a new JunitTest case TestAddController_standAlone...