In application engineering, the most common definition of a check case is a set of conditions or variables in which an evaluator to decide whether a requirement or use case on an application is partially or satisfied. It may take plenty of check cases to decide that a requirement is fully satisfied. To fully check that satisfies all the requirements of an application, must have at least three check case for each requirement unless the requirement has sub-requirements.In that situation, each sub requirement must have at least three check case. This is usually completed by a traceability matrix. Some methodologies, like RUP, recommended the creation of at least three check cases for each requirement. Three should check positive for the obligation and other negative tests should be performed. Written check cases should include a description of the functionality of the check, and the preparation necessary to ensure that the check can be conducted.If the application is created without formal requirements, then check cases can be written based on the normal operation of the programs accepted a similar class. In some schools, check, check cases are not written at all, but the activities and results are presented after the tests are executed.What characterizes a formal, written check case is that there is a known input and an expected outcome, which is made before the check runs. The known input should check a precondition and the result is expected to prove a post condition.In special circumstances, may be a need to run the check, produce results and then a team of experts will assess whether the results can be thought about a pass. This often happens in determining new product performance issue. The first check is taken as a baseline for later tests of the product release cycles.A variation of check cases are the most commonly used in acceptance tests. Acceptance testing is completed by a group of finish users or customers of the process to ensure that the process developed meets the specified requirements. User acceptance testing is often differentiated by the inclusion of the path happy or positive check cases.Written check cases are usually collected in check suites.