Randomized testing: Gotta Catch ‘Em All

> Chance does things well. If we apply this idea to unit tests or integration tests, we can make our tests much more unpredictable — and as a result, uncover issues that our minds would never have dared to imagine! For example, I recently discovered a [bug](https://github.com/gestalt-config/gestalt/issues/242) in a configuration management library that occurs when the `Locale` is set to `AZ`. 🤦🏼‍♂️ Another, even simpler, example: ```java int input = generateInteger(Integer.MIN_VALUE, Integer.MAX_VALUE); int output = Math.abs(input); ``` This can generate `-2147483648`... which is quite unexpected for an absolute value! 😉 Randomized tests can uncover these twisted edge cases... That’s what the Elasticsearch team has been doing for years using the [RandomizedTesting](https://labs.carrotsearch.com/randomizedtesting.html) framework to test all their Java code. Add to that real integration tests using [TestContainers](https://java.testcontainers.org/modules/elasticsearch/), and you’ll have a complete approach to tests that *regularly fail*! After this talk, you’ll never look at the `random()` function the same way again — and you’ll discover how (bad) luck can actually help you! 🍀