A Test Plan is a document that contains a complete set of test cases for a system along with other information about the testing process. A test plan is one of the standard forms of documentation. If a project does not have a test plan, it may lead to poor quality software because testing will inevitably be done in an ad hoc manner.
A test plan should be written long before testing starts. You can start to develop the test plan once you have developed the requirements. For this project, you will perform unit testing and system testing (perhaps integration tests as well). From the submission point of view, your unit tests will be written using JUnit. Your system tests are likely to be manual. Your system test plan will tell us how you plan to test the whole system. It needs to provide the following information for each test case: