11/14/24 - Boston Java Users ACM Chapter - TDD: It's easier than you think!

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TDD It’s easier than you think! Eric Deandrea Sr. Principal Developer Advocate @ Red Hat @edeandrea

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Who am I? ● 25+ years software development experience ○ ~11 years as DevOps Architect in financial services / insurance Java Champion ● Contributor to Open Source Projects Quarkus Spring Boot, Spring Framework, Spring Security LangChain4j (& Quarkus LangChain4j) Wiremock Microcks ● Build & deliver cloud-native development training programs ● Published author ● Avid boater & black belt in martial arts @edeandrea

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https://red.ht/quarkus-spring-devs ● Showcase & explain Quarkus, how it enables modern Java development & the Kubernetes- native experience ● Introduce familiar Spring concepts, constructs, & conventions and how they map to Quarkus ● Equivalent code examples between Quarkus and Spring as well as emphasis on testing patterns & practices 3

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Why are we here today?

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https://x.com/holly_cummins/status/1788138252572004441

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But first, Some basics

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end-to-end tests high realism high value

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end-to-end tests unit tests low effort high realism high value

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end-to-end tests unit tests integration tests low effort high realism high value

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end-to-end tests unit tests integration tests low effort high realism

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end-to-end tests unit tests integration tests low effort high realism tests with application server test REST endpoints tests with a database

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Unit testing

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Unit testing ● Isolate a “unit” within the application as a standalone entity

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Unit testing ● Isolate a “unit” within the application as a standalone entity ● Use mocking / spying to control dependencies of the unit during test

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Unit testing ● Isolate a “unit” within the application as a standalone entity ● Use mocking / spying to control dependencies of the unit during test ● Test all potential outcomes of a particular unit

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Mocking

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Mocking ● Complete mock / “fake” object

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Mocking ● Complete mock / “fake” object ● User must define interaction(s)

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Mocking ● Complete mock / “fake” object ● User must define interaction(s) ● Default behavior if not defined: do nothing

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Mocking ● Complete mock / “fake” object ● User must define interaction(s) ● Default behavior if not defined: do nothing ● Can verify intended behaviors occurred after test (verification-based testing)

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Spying

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Spying ● Partial mock / “real” object

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Spying ● Partial mock / “real” object ● User doesn’t need to define interaction(s)

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Spying ● Partial mock / “real” object ● User doesn’t need to define interaction(s) ● Default behavior if not overridden: perform actual operation on object

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Spying ● Partial mock / “real” object ● User doesn’t need to define interaction(s) ● Default behavior if not overridden: perform actual operation on object ● Useful for “watching” objects during tests & verifying intended behaviors occurred (verification-based testing)

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Integration testing

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Integration testing ● Treat application as a black box

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Integration testing ● Treat application as a black box ● Downstream services (db, message brokers, etc) need to be available

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Integration testing ● Treat application as a black box ● Downstream services (db, message brokers, etc) need to be available ● Application should be run & tested as its intended to be deployed

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Integration testing ● Treat application as a black box ● Downstream services (db, message brokers, etc) need to be available ● Application should be run & tested as its intended to be deployed ● Should be run before code is merged

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Today’s challenge

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229449 HTTP (REST) adoptions topic adoption-requests topic Get / Persist pet info

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https://bit.ly/tdd-easy

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Additional resources

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Kubernetes Native Java with Quarkus https://www.infoq.com/articles/native-java-quarkus Deployment Developer Joy ● Quickly & easily build Kubernetes-Native Java applications ● Industry leader in startup time and memory utilization for native and JVM applications ● One step native executable generation ● Leverage existing Java, Jakarta, MicroProfile, & Spring expertise ● Imperative & reactive APIs side-by-side ● Live coding with zero config

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https://www.oreilly.com/library/view/reactive-systems-in/9781492091714 https://developers.redhat.com/e-books/understanding-quarkus https://developers.redhat.com/e-books/practising-quarkus

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https://quarkus.io/blog/quarkus-superheroes-to-the-rescue https://github.com/quarkusio/quarkus-super-heroes Quarkus Superheroes