Pact consumer-driven contract testing extension

[holly-cummins]

Description

Pact is a widely-recommended framework for consumer-driven contract testing. Because Quarkus is optimised for microservices and consumer-driven contract tests are an important part of a microservices development workflow, Pact is particularly relevant for Quarkus.

Why is an extension needed? Functional issues

Although it is possible to use Pact with Quarkus (see https://github.com/skattela/pact-workshop-jvm-quarkus and https://github.com/holly-cummins/house-of-microservices-quarkus-contract-testing-sample), Pact tests do not work in continuous testing mode.

• Pact relies on Kotlin and is affected by classloading issues. See, for example, a reference to Pact problems on a broader issue about Kotlin classloading. The Pact issues need a bigger fix than just including the quarkus-kotlin extension.
• Pact tests also have problems if they store contracts in a local resources folder.

Usability enhancements

Although fixing the functional issues is most important, there are also a range of enhancements that could improve the Pact user experience:

• Eliminating the need to @BeforeEach a context.setTarget(new HttpTestTarget("localhost", 8081)) on every test
• Quarkus-style configuration of pact location and broker
• Dev UI view of contract contents and status
• Potentially, integration with other frameworks such as RestAssured, WireMock and OpenAPI. This is a complex area with existing activity and a number of existing converters.

Interested in this extension, please +1 via the emoji/reaction feature of GitHub (top right).

Configuration suggestion

pact.rootDir: # [existing system property, where to write generated pacts]
pact.writer.overwrite: # [existing system property, whether to overwrite generated pacts]
pact.readFrom: # [new property, universal config for pact location to eliminate need for per-test config, see https://docs.pact.io/implementation_guides/jvm/provider/junit#pact-source]

Additional context

This has been requested up occasionally in the broader community.

There was a long discussion on the google groups a year ago.

See also, for example, https://lightrun.com/answers/quarkusio-quarkus-consumer-driven-contracts-integrationsupport: "CDC is a big part of our Spring Boot microservice qa process, and it would be very desirable to have an equivalent in quarkus."

Note also that Pact is not the only contract testing option; Spring has Spring contract, although it is not as polyglot as Pact. It is also possible to use tools such as Schemathesis, Prism, and OpenAPI in combination (see a tutorial here).

[quarkus-bot]

/cc @evanchooly, @geoand

[holly-cummins]

I've got a prototype extension written which fixes the classloading issues, before anyone rushes off to try and fix. :)

[gsmet]

It would be hosted in the Quarkiverse, right?

[holly-cummins]

It would be hosted in the Quarkiverse, right?

That's my intention.

[holly-cummins]

This should also have the "area/testing" label.

[holly-cummins]

See also #6276, which is arguably a duplicate of this but which I missed in my searches (and this one has the extension-proposal issue type).

[holly-cummins]

It might also be possible to address #22611 with an extension but that would need a lot of thought.

[holly-cummins]

Could you do the repository-making, @gastaldi? :) Unless there are any objections?

[gastaldi]

@holly-cummins only if you don't mind waiting for me to return from my PTO on October😛

Could you create a PR in the quarkiverse-devops repo according to https://github.com/quarkiverse/quarkiverse-devops#workflow-for-new-repositories?

Here is an example: quarkiverse/quarkiverse-devops#91

[holly-cummins]

https://github.com/quarkiverse/quarkus-pact/ is the new home of the extension.