Property-Based Testing: Concepts and Examples

Property-based testing (PBT) validates the expected behavior of a system by checking it against a range of data points. A well-chosen set of properties will give the user a lot of confidence that the system is behaving as expected. The idea is that when the code is modified, failures in the tests reveal problems that would not have been found otherwise. This talk will cover the basic principles and several examples of PBT, using the jqwik library.

PBT allows you to define invariants (like reversing a list twice should result in the original list) and verify that they hold given generated changes that include a wide range of random inputs, including edge and corner cases. The jqwik library works well with JUnit to provide an important part of your testing strategy.

About Kenneth Kousen

Ken Kousen is a Java Champion, several time JavaOne Rock Star, and a Grails Rock Star. He is the author of the Pragmatic Library books “Mockito Made Clear” and “Help Your Boss Help You,” the O'Reilly books “Kotlin Cookbook”, “Modern Java Recipes”, and “Gradle Recipes for Android”, and the Manning book “Making Java Groovy”. He also has recorded over a dozen video courses for the O'Reilly Learning Platform, covering topics related to Android, Spring, Java, Groovy, Grails, and Gradle.

His academic background include BS degrees in Mechanical Engineering and Mathematics from M.I.T., an MA and Ph.D. in Aerospace Engineering from Princeton, and an MS in Computer Science from R.P.I. He is currently President of Kousen IT, Inc., based in Connecticut.

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