IBM Research has developed Use Case Based Testing (UCBT), which is a technique for generating test cases and recommended configurations for system level testing. In our approach, testers build a test model based on the standard UML notions of use cases, actors, and the relationships between these elements. The use cases are enhanced with additional information, including the inputs from actors, the outputs to the actors, and how the use case affects the state of the system.
Newly developed algorithms use this model to generate a test suite which provides a specified level of coverage of each use case. We also generate workload configurations that combine the test cases according to requirements specified in the model. The generation algorithm performs minimization to reduce the number of test cases required to cover the system to the specified level. The workload configurations are based on desired percentages associated with each actor that the tester provides. These features form a powerful basis for model-based test case generation.
What testing phase does UCBT address?
UCBT addresses phases where the tester is interested in exploring behavior that flows through multiple use cases, which are typically the late function, system, and solution phases of the test life cycle. In late function level test, the tester has tested the use cases individually, and is now interested in looking at combinations of the use cases. System test addresses the situation when all required functionality for the system is present, and the tester seeks to ensure the proper functioning of the system as a whole. An important component of system test is also ensuring that the system can handle customer-like scenarios and workloads. Solution test addresses the situation in which several complete systems are combined to provide complex functionality through some process that involves the systems. These processes can be captured, modeled, and tested using UCBT. What does the tester do in UCBT?
To do UCBT, the tester needs to identify four things:
the use cases of interest,
the actors involved in using the system,
the input, output, and system effects for the use cases,
the flows of interest between the use cases.
UA use case is a semantically meaningful function that provides some value from the user's point of view. For example, saving a file in a word processing system would be represented by the Save File use case. Each use case can have input parameters associated with it, and for each parameter, a set of logical partitions of the values that parameter can take may be identified. Finally, the use cases can be connected using flows that describe a sequence of use case that are performed to accomplish some goal.
What is produced by UCBT Tool?
UCBT produces two types of test cases. The first type are abstract test cases, which are not executable. These are suitable for incorporation in a test plan and are provided in structured English. They show the ordering of use cases to be performed and the inputs and expected results that each use case should have during the test. The second type of test cases are in a format known as ATS, which can be used to create executable test cases using another tool known as TCBeans. TCBeans was developed by IBM Research in Haifa. The test suite produced by UCBT is minimized in size by performing a two pass optimization based upon the input parameter interactions that the tester specifies, as well as the flows of interest. This ensures that the number of test cases is reasonable, so execution and evaluation can be done with a feasible amount of effort.
