2-20-25 - vJUG - Avoiding pitfalls with modern microservices testing

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Eric Deandrea Java Champion Sr. Principal Developer Advocate Red Hat @edeandrea Drawings courtesy of Holly Cummins Avoiding common pitfalls with modern microservices testing

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@edeandrea #RedHat https://red.ht/quarkus-spring-devs • How Quarkus enabled modern Java development & the Kubernetes-native experience • Introduce familiar Spring concepts, constructs, & conventions and how they map to Quarkus • Emphasis on testing patterns & practices

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@edeandrea #RedHat

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@edeandrea #RedHat “Every time we touch one microservice, all the others break.”

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@edeandrea #RedHat

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@edeandrea #RedHat “My end-to-end test environment is only up the third weekend every month.”

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#RedHat @edeandrea Disclaimer!

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#RedHat @edeandrea Disclaimer! I am not a tester. (or even test expert)

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#RedHat @edeandrea Disclaimer! I am not a tester. (or even test expert) That’s ok– testing is every developer’s job!

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@edeandrea #RedHat Why is testing microservices so hard?

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@edeandrea #RedHat Netflix microservice architecture

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@edeandrea #RedHat Death star “That’s no moon. It’s our architecture.”

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@edeandrea #RedHat Do microservices solve all problems?

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@edeandrea #RedHat A microservice system: a portrait

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@edeandrea #RedHat Netflix microservice architecture

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@edeandrea #RedHat Netflix microservice architecture Testing with microservices is easy!

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@edeandrea #RedHat Netflix microservice architecture Testing with microservices is easy! My services are so small! Everything is decoupled!

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@edeandrea #RedHat Netflix microservice architecture Testing with microservices is easy! My services are so small! Everything is decoupled! But….. If you only test the points, And not the lines…. Does the thing actually work?

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@edeandrea #RedHat distributed != decoupled

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@edeandrea #RedHat Understand the coupling

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#RedHat @edeandrea “It is all that is left unsaid upon which tragedies are built.” - Kreia, Star Wars Knights of the Old Republic II: The Sith Lords

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#RedHat @edeandrea

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#RedHat @edeandrea This is not the answer.

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#RedHat @edeandrea “You lied to me. How many other lies have I been told by the Council? And how do you know that you even have the truth?” – Anakin Skywalker

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#RedHat @edeandrea “Many of the truths that we cling to depend on our viewpoint.” — Obi-Wan Kenobi, Return of the Jedi

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#RedHat @edeandrea “In my book, experience outranks everything.” — Captain Rex, The Clone Wars

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@edeandrea #RedHat Ok, so how do we try these out?

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#RedHat @edeandrea Get good at testing.

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#RedHat @edeandrea Get good at testing. And automation.

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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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#RedHat @edeandrea their code our code Why mocks aren’t enough

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#RedHat @edeandrea our mock our code Why mocks aren’t enough

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#RedHat @edeandrea our mock our code ✔ tests Why mocks aren’t enough

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#RedHat @edeandrea our mock our code Why mocks aren’t enough

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#RedHat @edeandrea our mock our code ✔ tests ✘ reality our code their actual code Why mocks aren’t enough

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@edeandrea #RedHat a mock stormtrooper

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@edeandrea #RedHat a mock stormtrooper “Aren’t you a little short for a stormtrooper?” – Princess Leia

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#RedHat @edeandrea https://www.flickr.com/photos/jdhancock/4811282106 Source: https://medium.com/jung-skywalker/star-wars-symbology-luke-han-and-how-to-face-the-abyss-e9fa966319b5

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@edeandrea #RedHat Demo The limitations of unit tests https://github.com/edeandrea/pact-quarkus-wookie-carpet-demo

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@edeandrea #RedHat “Will someone get this big walking carpet out of my way?” – Princess Leia Demo The limitations of unit tests https://github.com/edeandrea/pact-quarkus-wookie-carpet-demo

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@edeandrea #RedHat “Will someone get this big walking carpet out of my way?” – Princess Leia Demo The limitations of unit tests https://github.com/edeandrea/pact-quarkus-wookie-carpet-demo

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@edeandrea #RedHat

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@edeandrea #RedHat A potential solution

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@edeandrea #RedHat How to test a fire alarm?

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@edeandrea #RedHat

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@edeandrea #RedHat How NOT to test a fire alarm!

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@edeandrea #RedHat

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Unit testing a fire alarm

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@edeandrea #RedHat uh … is that enough?

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@edeandrea #RedHat

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@edeandrea #RedHat contract testing a fire alarm

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Photo: https://www.westcoastfirepits.com/shop/death-star

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Photo: https://www.westcoastfirepits.com/shop/death-star How to SAFELY burn a Death Star!

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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 high value contract tests

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#RedHat @edeandrea our code their code A better mock

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#RedHat @edeandrea our code their code contract test mock functional test A better mock

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#RedHat @edeandrea ✔ our tests ✔ their tests ✔ reality our code their code contract test mock functional test A better mock

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#RedHat @edeandrea our code their code A better mock

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#RedHat @edeandrea our code their code contract test mock functional test A better mock

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#RedHat @edeandrea ✔ our tests ✘ their tests ✘ reality our code their code contract test mock functional test A better mock

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#RedHat @edeandrea A better mock our code their code

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#RedHat @edeandrea A better mock our code their code contract test mock functional test

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#RedHat @edeandrea ✘ our tests ✔ their tests ✘ reality A better mock our code their code contract test mock functional test

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@edeandrea #RedHat Pact Contract Testing

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@edeandrea #RedHat Demo

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@edeandrea #RedHat “Help me, Pact! You’re my only hope!” – Princess Leia (almost) Demo

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@edeandrea #RedHat “Uh, you’re telling me that consumers can break a provider’s tests?”

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#RedHat @edeandrea Consumer-driven contract testing

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#RedHat @edeandrea consumer Consumer-driven contract testing

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#RedHat @edeandrea contract consumer tests mock declare (Pact) Pact fi le Consumer-driven contract testing Spring Cloud Contract Pact

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#RedHat @edeandrea contract consumer tests provider mock declare (Pact) contract tests verify Pact fi le Consumer-driven contract testing Spring Cloud Contract Pact Pact

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#RedHat @edeandrea contract consumer tests provider mock declare (Pact) contract tests verify Pact fi le Consumer-driven contract testing ☑ rich semantic testing Spring Cloud Contract Pact Pact

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#RedHat @edeandrea contract consumer tests provider mock declare (Pact) contract tests verify Pact fi le Consumer-driven contract testing ☑ rich semantic testing ☑ provider can ‘develop to the contract’ instead of developing speculatively (TDD) ⛔ existing spec assets cannot be re-purposed Spring Cloud Contract Pact Pact

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#RedHat @edeandrea …but I want to just use Swagger/OpenAPI

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@edeandrea #RedHat Is Pact always the best choice?

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#RedHat @edeandrea Provider-driven contract testing

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#RedHat @edeandrea consumer provider Provider-driven contract testing

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#RedHat @edeandrea contract consumer provider OpenAPI Provider-driven contract testing generate (OpenAPI snapshot of current implementation) other protocol specs

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#RedHat @edeandrea contract consumer provider contract tests verify OpenAPI Provider-driven contract testing generate (OpenAPI snapshot of current implementation) other protocol specs Schemathesis Microcks

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#RedHat @edeandrea contract consumer tests provider mock contract tests verify OpenAPI Provider-driven contract testing generate (OpenAPI snapshot of current implementation) other protocol specs ☑ familiar contract format ☑ provider does not need comms with consumers Prism Microcks Schemathesis Microcks

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#RedHat @edeandrea Is OpenAPI enough? It has the same syntax, but the semantics are different.

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#RedHat @edeandrea Is OpenAPI enough? It has the same syntax, but the semantics are different. It looks the same, but the behaviour is different.

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#RedHat @edeandrea Is OpenAPI enough? It has the same syntax, but the semantics are different. It looks the same, but the behaviour is different. Looks like a storm trooper. Behaves like Luke. (because it it is Luke)

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@edeandrea #RedHat Demo: Semantic testing with Pact

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#RedHat @edeandrea how annoying, the provider is returning 204. the contract expects 404, so my test is broken. quarkus will return 204 by default. 204 vs 404 - it’s more about the theory behind REST...if a caller asks for a resource the server doesn't have, it should be a 404 - same way if a user types in an invalid URL into the browser ugh, it’s too late at night to care about REST theory. I’m just going to update the expectations in the test to match reality. what?! why is my other contract test broken now? oh … because what I’m changing is a mock…. Based on a true story….

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@edeandrea #RedHat

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@edeandrea #RedHat soo … microservices testing is hard limit end-to-end testing mocks will not be enough contract testing can rescue you

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@edeandrea #RedHat Additional Resources

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#RedHat @edeandrea https://github.com/quarkusio/quarkus-super-heroes More realistic sample application (fewer wookies)

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#RedHat @edeandrea Kubernetes Native Java with 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 https://www.infoq.com/articles/native-java-quarkus

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#RedHat @edeandrea 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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@edeandrea #RedHat ® Thank you! @edeandrea