Lies, Damn Lies, and Code Coverage

Code coverage gives us confidence that our unit tests are effective and thoroughly test our code, but is this confidence justified? Is it possible to have good code coverage numbers, but still have ineffective tests? Mutation Testing is a technique for ensuring a test suite thoroughly tests a piece of software and that any semantic change made to the software will cause the test suite to fail. This presentation will discuss what mutation testing is, why you should be doing it, and give examples of mutation testing in TypeScript.