Making live programming practical by bridging the gap between trial-and-error development and unit testing

Live programming environments are powerful experimental tools that enable programmers to write programs in a trial-and-error way thanks to its quick feedback. Since the feedback includes intermediate data such as a control flow and a history of variable bindings, the live programming environments integrate debugging into editing. One of the disadvantages of such interactive systems is that tests are transient. If we wrote persistent tests using an automated testing framework like JUnit, we could not fully enjoy "liveness." This is because we need to write proper parameters and expected values in advance. We develop Shiranui, a live programming environment with unit testing features. In Shiranui, the programmers can check functions' behaviors in a lively manner and then convert the results into persistent test cases. One of the features enables the programmers to make a test case from an intermediate result that are found in a debugging process. It makes constructing error-reproducing-tests easier.