What is a Test Plan?
A Test Plan is a document describing the scope, approach, resources, and schedule of intended testing activities. It identifies test items, the features to be tested, the testing tasks and who will do each task (roles and responsibilities) and any risks and its solutions.
What does it include?
A Test Plan includes Heading, Revision History, Table of Contents, Introduction, Scope, Approach, Overview, different types of testing that will be carried out, what software and hardware will be required, issues, risks, assumptions and sign off section
Test_Plan_Sample (Click this link to see how a test plan looks like)