Use case include is a directed relationship between two use cases which is used to show that behaviour of the included use case (the addition) is inserted into the behaviour of the including (the base) use case.
We draw the use case for the users perceptive, which is helpful for the development team to understand the user’s requirement perfectly. We cases are designed by Business analyst. After gathering the requirement and analysis part business analyst are writing down the use cases, on basis of which he drawn the Use case diagram.
In use cases business analyst write down the basic flow of an activity as well an alternate flow of an activity. Basis flow the complete flow where activity stating point to the end point. An alternative flow means stoppage / hurdle between the basic flows (e.g. ATM machine, if we inserted card inside of the machine and put the wrong credentials then the customer cannot do the transaction, for this situation we called as an alternative flow.)
With the help of use cases business analyst drawn the UML diagram, where he used few of the symbols to highlight the performed action from eg, include, exclude, generalisation etc.
On the basis of use cases testing team prepare the test cases to test the functionality of the application. After testing team completing the testing phrase of the project then business analyst needs to map those entire requirement with test cases which performed by testing team with the help of RTM (Requirement traceability matrix).