Professor X is a brand new, open source Mutation Testing tool for Typescript.
Mutation Testing is a branch of software testing which takes code within a target project and inserts bugs (mutations) into the code. It then runs the project’s unit tests and evaluates their output. If no unit tests fail, then the mutation has survived. If one test fails then the mutation has been detected and killed by the unit tests (This is what we want).
The more surviving mutants, the worse our mutation score. The goal is to get this as high as possible.
Mutants can be killed by adding more unit tests which cover the bugs. If a project has a large number of unit tests, a developer can, more safely, refactor functions without fear of breaking another piece of functionality.
Professor X Repository: